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    1. Cloud formation
    Generally, upward motion of moist air is a prerequisite for cloud formation, downward motion dissipates it. Ascending air expands, cools adiabatically and, if sufficiently moist, some of the water vapour condenses to form cloud droplets. Fog is likely when moist air is cooled not by expansion but by contact with a colder surface.

    Water vapour generally needs something to condense onto to form liquid. Common airborne condensation nuclei are dust, smoke and salt particles; their diameter is typically 0.02 microns (micrometres) but a relatively small number may have a diameter up to 10 microns. Maritime air contains about one billion nuclei per cubic metre (typically salt), while polluted city air contains many more. The diameter of a cloud droplet is typically 10 to 25 microns and the spacing between them is about 50 times the diameter — perhaps 1 mm — with maybe 100 million droplets per cubic metre of cloud. The mass of liquid in an average density cloud is approximately 0.5 gram per cubic metre.

    Above the freezing level in the cloud, some of the droplets will freeze if disturbed by contact with suitable freezing nuclei or with an aircraft. Freezing nuclei are mainly natural clay mineral particles, bacteria and volcanic dust, perhaps 0.1 microns in diameter but up to 50 microns. There are rarely more than one million freezing particles per cubic metre; thus there are only enough to act as a freezing catalyst for a small fraction of the cloud droplets. Most freezing occurs at temperatures between –10 °C and –15 °C.

    The balance of the unfrozen droplets remains in a supercooled liquid state, possibly down to temperatures colder than –20 °C. Eventually, at some temperature warmer than –40 °C, all droplets will freeze by self-nucleation into ice crystals, forming the high-level cirrus clouds. In some cases, fractured or splintered ice crystals will act as freezing nuclei. The ice crystals are usually shaped as columnar hexagons or flat plate hexagons. Refer to sections 3.5.2 and 12.2.2.

    Condensation of atmospheric moisture occurs when: the volume of air remains constant but temperature is reduced to dewpoint; e.g. contact cooling and mixing of different layers the volume of an air parcel is increased through adiabatic expansion evaporation increases the vapour partial pressure beyond the saturation point a change of both temperature and volume reduces the saturation vapour partial pressure.
    2. Cloud classification
    2.1 Cloud genera
    Cloud forms are based on ten main genera, conventionally grouped into three altitude bands — high, medium and low — plus a vertically developed group. About 90% of atmospheric moisture exists below 20 000 feet with 50% or more in the band below 6500 feet. The altitudes included in each band are dependent on the thickness of the troposphere at nominal locations — tropical, temperate or polar. These are:
      Cloud altitude bands   Tropical Australia Temperate Australia Antarctic High 20 000–60 000 16 000–43 000 10 000–26 000 Medium 6500–26 000 6500–23 000 6500 –13 000 Low 0–6500 0–6500 0–6500
    High clouds
    A two-letter code is used to identify cloud genera in meteorological reports, observations and aviation area forecasts. Cirrus [CI] (Latin for 'curl'): white patches, banners, threads or delicate filaments of ice crystals. They often appear in patches of individual 'generating heads' with streaks of crystals falling from them thus forming comma-shaped or hooked 'mares' tails'. Cirrus clouds may merge into CS or CB. They are formed by widespread ascent, but sometimes by upper level turbulence in a smaller area. Cirrostratus [CS]: a thin, transparent, amorphous, whitish veil of smooth or sometimes finely fibrous appearance, appearing over much of the sky at very high altitudes. They create the appearance of halos about the sun or moon. Cirrostratus may merge into CC or possibly AS, and are formed by widespread ascent and may thicken when preceding a cold front. Cirrocumulus [CC]: thin, white patches, sheets or rows with small, regularly arranged elements or cloudlets in the form of grains or ripples, which may be merged or separate; sometimes with an appearance like fish scales — a 'mackerel sky'. The apparent width of elements is less than one degree. Cirrocumulus elements may merge together to form CS or separate into CI mares' tails. CC are produced by turbulence aloft — often associated with a front or upper-level disturbance.  
    Medium-level clouds
    Altostratus [AS]: grey/bluish sheet, with coverage of possibly 8 oktas, of uniform appearance. They are often striated or fibrous, having parts thin enough to reveal a vague sun without any halo but possibly a corona. Altostratus often merges into NS. They are caused by widespread ascent and are usually associated with a front or upper-level disturbance. Altocumulus [AC]: white/grey patches, bands or sheets of regularly arranged globular elements (sometimes called mackerel sky) — waves or rows with light shading, closely packed or merged. The element width is 2 to 5 degrees. (A finger width at arm's length is approximately 2 degrees; the spread between the tips of the little finger and thumb when a hand is splayed is about 22 degrees.) Altocumulus often shows coloured patches (irisation) around elements when illuminated by the sun or moon; a corona may be visible. They are usually caused by turbulence and are not associated with a change in the weather. Nimbostratus [NS] (from the Latin 'nimbus' = cloud, aureole): thick, dense, dark grey layer, often with a ragged or diffused base, with continuous precipitation. Coverage is often 8 oktas. Scud (pannus) may form beneath it. Invariably they occur at medium level, but usually extend to high level and merge with AS; they may also extend to low levels and envelop hills. Nimbostratus are produced by widespread ascent.  
    Low-level clouds
    Stratocumulus [SC]: grey/whitish patches, sheets or layers of separate or partly merged globular masses or rolls with dark shading and generally irregular appearance. If regularly arranged, the separate elements have apparent width exceeding 5 degrees. Coverage is often 8 oktas and may be penetrated by large CU or CB. Stratocumulus are probably the most frequently seen cloud in south-eastern Australia and are most frequent in winter anticyclones — 'anticyclonic gloom' — when moist air is trapped under an inversion. They are particularly noticeable around Melbourne. Stratus [ST] (Latin = spread, laid down): grey, uniform layer with fairly even base from which drizzle may descend. The sun outline may be visible. Stratus envelops low hills. They sometimes appear in ragged patches, which are produced by frictional turbulence or possibly orographic ascent. Cumulus [CU] (Latin = heap): white, heaped tops with generally grey, horizontal bases. Form is usually sharply outlined but may be ragged if evaporating. Vertical development varies greatly with atmospheric buoyancy, and bases can be at low or medium levels. Cumulus are formed by convection or possibly orographic ascent.  
    Vertically developed clouds
    Cumulonimbus [CB]: heavy, dense cloud with massive vertical development, bases at low or medium levels, with tops possibly reaching (even overshooting) the tropopause. They may have a 'boiling' appearance during their vertical development stage. The base is usually very dark with lighter inflow areas. They are associated with heavy showers or virga — precipitation that evaporates before reaching the surface. Frequently low, ragged, turbulence cloud is mixed beneath it. Cumulonimbus are produced by vigorous convection. Refer to section 3.6.
    For more information on the types and dangers of thunderstorms read sections 9.4 through 9.7. Towering cumulus [TCU]: CU with cauliflower appearance, often of great vertical extent. Properly known as cumulus congestus [CU CON].   Cloud structure and composition Cloud type Height of base Vertical extent Composition Associated precipitation CI 20 000 + usually thin* ice crystals fall streaks CS 20 000 + usually thin ice crystals nil CC 20 000 + usually thin crystals/droplets nil AS 6000 – 20 000+ up to 15 000 usually crystals, occasionally mixed rain/snow AC 6000 – 20 000 usually thin usually droplets to –10 °C, some crystals to –30 °C occasionally mixed rain, drizzle NS 0 – 8000+ merges into AS water droplets steady rain, snow, ice pellets SC 1500 – 4000 500 – 3000 mainly droplets down to –15 °C rain, drizzle, virga ST 0 – 2000 200 – 1000 usually water droplets drizzle CU, TCU 1500 – 15 000 up to 15 000 water droplets rain showers CB 1500 – 5000 15 000 – 35 000+ mainly droplets to –15 °C, mixed at lower temperatures rain/snow showers/virga, hail, ice pellets
    *With fall streaks, the vertical extent of CI may exceed 5000 feet
    Photographs and more information on cloud classes and identification techniques can be found at the Australian Severe Weather website.
    2.2 Cloud species
    Each of the cloud genera are subdivided into species by the addition of a common species descriptor (with a three-letter code), according to cloud shape and structure. Fibratus [FIB]: CI and CS in the form of long, irregularly curved or nearly straight parallel filaments, but without tufts or hooks. CI FIB, CS FIB Spissatus [SPI]: dense or thickened CI plumes or CS, often originating from, or the remnants of, a CB anvil. Generally has a stormy appearance, looking greyish when viewed towards the sun. CI SPI, CS SPI Uncinus [UNC] (Latin = hook): CI with filaments that are hooked or comma-shaped. 'Mares tail cirrus'. Ice crystals are forming at the high point of the fall streak where a small tuft of cloud may appear — the generating head. The crystals forming the tail are falling through atmospheric layers of varying wind velocity and persist for quite a while before evaporating. CI UNC Nebulosus [NEB]: CS and AS as an indistinct veil lacking any detail. Also applied to low amorphous ST — lifted fog. CS NEB, AS NEB, ST NEB Stratiformus [STR]: AC and SC, occasionally CC, spread out into an extensive sheet or layer. CC STR, AC STR, SC STR Lenticularis [LEN]: (from the Latin 'lentil shaped') AC of orographic standing wave origin, sometimes CC or SC; occurs as a biconvex shape with a sharp margin, and often elongated if produced by a long ridge. They sometimes display iridescence. May form in long bands parallel to the Great Dividing Range and extend 50 to 100 nm downstream, towards the east; see mountain waves. When there are alternating layers of drier and moister air a tall, well-developed lenticularis formation may resemble an inverted stack of dinner plates, occasionally seen in the mountain areas of south-eastern Australia. CC LEN, AC LEN, SC LEN Castellanus [CAS]: having a turreted or crenellated appearance and connected to a common cloud base line. They are generally AS (but forming AC), or sometimes SC, CI or CC, signifying increasing instability. AC CAS may precede the development of CB. Floccus [FLO] (Latin = tuft of wool): CI, CC or particularly AC occurring in chaotic form, like a flock of sheep, each unit having a ragged base and a small cumuliform tuft above; 'thundery skies'. Often accompanied by virga. If developing CU reach this humid and unstable layer then energetic CB may develop. Fractus [FRA]: ST or CU shreds with broken, ragged or wispy appearance, associated with formation or dispersion of low cloud. CU FRA often appears early in the morning, rising only slightly above the condensation level; they are also found in precipitation under CB. ST FRA is much darker than CU FRA when found under CB. ST FRA normally forms below NS or AS, and derives moisture from evaporating raindrops or surface water. Uplift from near-surface turbulence may produce ST FRA, particularly in areas of rising ground or low hills. If forming without overlying cloud, ST FRA forewarns of worsening low-level visibility and ST formation. Pannus or scud is a mix of CU FRA and ST FRA. Humilis [HUM] (Latin = lowly): CU with small development and usually flattened at an inversion that is not far above the condensation level — 'fair weather CU'. Lifetime is 5 to 45 minutes. CU HUM Mediocris [MED] (Latin = of middle degree): CU of intermediate vertical growth, occurring at no more than 3000 feet. They have tops showing small protuberances that are not actively growing. CU MED Congestus [CON] (Latin = piled up): CU with cauliflower appearance, often of great vertical extent, perhaps 10 000 feet; generally known as towering CU [TCU]. Freezing does not occur. CU CON may produce heavy showers or microbursts, the latter particularly so in northern Australia. Calvus [CAL] (Latin = bald): developing CB prior to anvil stage, but at least some of its upper part is losing its CU outline due to freezing. CB CAL Capillatus [CAP] (Latin = hair): CB with distinct icy, upper fibrous or striated cirriform appearance. Frequently anvil-shaped, or untidy plumes, or disordered cirrus mass. CB CAP
    2.3 Cloud varieties
    Each of the cloud genera and species can be further classified into varieties by use of a common descriptor for element arrangement, transparency, etc. Intortus [IN]: irregularly curved or tangled CI. Vertebratus [VE]: CI looking like fish bone, ribs or vertebrae. Lacunosus [LA]: thin CC or AC with regularly spaced, net-like holes or a honeycomb appearance. Undulatus [UN]: parallel undulations in patches, sheets or layers of CC, CS, AC, AS, SC or ST caused by waves in the airstream. Radiatus [RA]: broad, parallel bands of CI, AC, AS, CU or SC appearing to converge towards a radiation point on the horizon, or both horizons. Duplicatus [DU]: more than one layer of CI, CS, AC, AS or SC at slightly different levels. The winds at each layer are usually blowing in slightly different directions. Translucidus [TR]: AC, AS, SC or ST in large sheets thin enough to show position of the sun or moon. Perlucidus [PE]: AC or SC in broad layers or patches with small lanes that allow the sky to be seen. Opacus [OP]: AS, AC, SC or ST that completely masks the sun or moon.
    2.4 Accessory clouds
    There are three cloud types that only exist in association with one of the main cloud genera: Pileus (Latin = cap, hood, like mushroom cap): a short-lived, smooth lenticular cloud appearing in a humid stable layer above a CB or TCU when the rising thermal deflects the moving air in the layer up and over into the condensation level. Further CB or TCU development will push through the cap cloud, which may hang on as a temporary collar. There is a good photograph of such an event in the Sydney Storm Chasers website. In strong shear conditions, the cap cloud may form downwind. Velum (Latin = veil): a thin, wide and persistent sheet of cloud accompanying a CB or TCU and forming in a humid, stable layer. Velum is dark in contrast to the convective cloud that generally rises through it. Pannus (Latin = piece of cloth): a mix of CU FRA and ST FRA, or just a lump of ST. Scud rapidly forms or reforms generally at lower levels under precipitating CU, AS, CB or NS bases in turbulent lifting conditions, particularly when air rises rapidly at the edge of cool moist outflow, or a downburst or in upflow caused by the topography — and exacerbated by evaporation of moisture from forest canopies. Scud changes size and shape constantly, and may be drawn into the cloud base. Flight in a locality where pannus is forming — scud running — is a very dangerous activity for aviators.
    2.5 Cloud features
    Some notable cloud features are: Incus (Latin = anvil): the anvil of a large CB, particularly a multicell or supercell storm, which has spread out, usually when upper-level winds are light. A severe storm attains maximum vertical development when the updraught reaches a stable layer which it is unable to break through — often the tropopause — and the cloud top spreads horizontally in all directions to form an overhanging anvil.

    The photograph and text below appeared in the "NSW Lightning Bolt" of August 1997 — produced by the Severe Weather Section of the Bureau of Meteorology, NSW. That anvil had a spread of about 30 km. The rollover around the underside of the anvil indicates rapid expansion.

    "Rose's magnificent photo (below) of a storm cloud near Millthorpe in NSW is familiar to many Bureau staff from the 1996 Weather Calendar, a 1995 Bureau Christmas card, and the new thunderstorm poster. The story of how the photo came to be taken may attract the writers at the Disney Studios. Rose relates the tale:

    '... my son Ian phoned to tell me about the clouds and to ask if I had a spare film, as his camera was empty. I tied a film to our kelpie's collar and sent him down the hill to Ian. Meanwhile, Ian's daughter Melanie was cycling up to get the film ... by the time they both met Ian the cloud had started to break up. Fortunately by then I had climbed two fences and taken the two shots ...' " Arcus (Latin = arch, bow or curve): a shelf-like cloud indicating the inflow region at the leading edge of a thunderstorm or a squall line. If conditions are very humid the shelf cloud will be a low, thick, curved and well-formed cloud bank. If there is a sharp, severe gust front there may be a vortex indicated by twisting scud under, and leading up to, the shelf. A roll cloud, like a horizontal tube, may develop if the leading edge of the shelf speeds up and detaches. SC, AC roll clouds are also associated with mountain waves and solitary waves.
      Granitus: a localised cloud (always forming below the lowest safe altitude [LSALT] marked on aeronautical charts) enclosing and obscuring a large chunk of land, usually in the form of a hill or peak. Granitus is sometimes known as 'stuffed CU', which refers to both the solid content and the consequences of entering such a cloud.
      Wall cloud: a localised, possibly rotating, lowering from a CB cloud base. Situated at the main updraught with a diameter ranging from 0.5 km to 5 km. Refer to section 9.5.   The Sydney Storm Chasers website has many images of thunderstorm features.
    There are good photos of wall clouds, arcus, pannus and mammatus.   Mammatus: hard, downward protuberances, pouches or bulges from the underside of a CB anvil (frequently) or CI, CC, AS, AC or SC, indicating descending pockets of small droplets or ice crystals. The sinking, saturated air is cooler than the air around it. As it sinks it warms, but warming is retarded because some of the heat is used in evaporating cloud droplets in the saturated air. If more energy is required for evaporation than is generated by adiabatic warming, then the air and the cloud pouches will continue to sink and will elongate the protuberances. The mamma associated with CI and CC are very shallow, forming undulations in the cloud trails. Mamma associated with CB are an indication of a dissipating storm rather than severe turbulence.
      Fall streaks: virga-like showers of ice crystals or snowflakes from CI generating heads, which sink at rates up to 0.5 m/sec but slowing as they sublimate. As they sink through several thousand feet they become deflected by falling into winds of lower velocity, or slow through sublimation, and thus appear to trail back from the parent head as hooks, mares' tails, etc. Dense streaks combined with a strong drop in wind speed produce jet-stream banners — CI features that stream with the wind. AS and most stable cloud features lie across the wind.
      Billow clouds: AC and AS found in a series of regular bands with clear areas between of similar width, occurring most frequently at 15 000 to 25 000 feet. At other times the upper surface (usually but could be the lower surface) of the cloud may have regular wave-like troughs and crests – undulatus.

    When a higher-level inversion occurs, the upper and lower air layers are generally stable. If there is a significant difference in wind velocity between the layers then there is vertical wind shear at the interface, and a phenomenon known as 'Kelvin-Helmholtz shearing instability' causes the formation of long but short-lived waves across the interface — in much the same way as ocean waves — which grow in amplitude until they curl up and break. The waves produce an extensive but shallow area of clear air turbulence. If sufficient moisture exists, the waves become visible as Kelvin-Helmholtz billows. Billows always move with the wind so that in wave clouds they appear to move from the front to the rear of the formation, evaporating in the troughs and re-condensing in the crests. Kelvin-Helmholtz instability produces the ripples seen when a light wind blows across a pond of water.  
    Pyrocumulus: CU initiated by bushfire thermal activity. Ray Kennedy's photograph below shows a CU CON building above the brown smoke during the Gippsland bushfires on New Year's Day 1998.  

    2.6 Stratospheric clouds Nacreous (mother-of-pearl) clouds are rare, high-latitude, stratospheric clouds resembling CC LEN or AC LEN. Small patches are occasionally formed in winter, usually in stationary standing waves, and often in the lee of mountain ranges, which provide abrupt uplift. They usually occur in the ozone layer at about 25 km with temperatures down to –80°C or –90°C. Nacreous clouds are probably composed of spherical ice crystals about one to two microns diameter. Brilliant iridescence is shown at angular distances up to 40 degrees from the sun, and green and pink colours predominate. These clouds are brightest at sunset but are rarely seen in daylight.
      Noctilucent clouds [NLC] are rare, tenuous, mesospheric cloud formations only seen from higher-latitude locations, normally around 40° to 60° south, against a twilit (nautical and astronomical) sky in summer. Sufficient contrast for observation occurs when the sun is between 6° and 16° below the horizon with maximum contrast at 10° when solar illumination and light scatter is at the maximum. They are seen close to the sunward horizon and extend maybe 20° above, along the twilight arch, although the clouds can be seen at a much higher elevation. The clouds appear to be near the mesopause at about 80 km and are moving with the zonal easterlies. They resemble high CI with pronounced band or wave structures, commonly herring-bone, bluish-white to pure white with yellow beneath. They are probably composed of cosmic dust with thin ice deposition, saturation of traces of water vapour being reached through orographic waves resonated from the earth's surface, or possibly oxidation of atmospheric methane.  
    The Australian Severe Weather website has many excellent images grouped into cloud classifications, cloud features and atmospheric phenomena. Also the Cloud Appreciation Society website is well worth a visit.

    2.7 ICAO / WMO Cloud continuity scale
    SKC — sky clear, no cloud. FEW — few clouds, one to two oktas cover. SCT — scattered, 3 – 4 oktas cover. Clear intervals between clouds predominate. BKN — broken, 5 – 7 oktas. Cloud masses predominate. OVC — overcast, 8 oktas. Continuous, no clear intervals.  
    3. Lifting sources
    There are four main processes that provide the lifting source for moist air to form cloud: convection frictional turbulence orographic ascent convergence or widespread ascent.  
    3.1 Convection
    When air flows over a surface heated by solar radiation, the surface contact layer is heated by conduction, and some of the heat is transported upward by molecular motion and small turbulent eddies. If the incoming energy is sufficient, the temperature in the lower layer increases and thermals rise from the heated contact layer — initially as bubbles of buoyant air, and then develop as columns with 100 – 300 metre diameters. The strength of the thermal depends on the heating:

    Thermal vertical velocity Thermal strength Knots Feet/min Metres/sec Weak 1 – 2 100 – 200 0.5 – 1 Moderate 2 – 6 200 – 600 1 – 3 Strong 6+ 600+ 3+
    Circling within a thermal (thermalling) is a prime source of uplift for soaring paragliders, hang gliders and sailplanes, and particularly so in the summer. In hot, dry areas of Australia, thermals exceeding 1000 feet/min are common.
    The rising thermal cools at about the DALR of 3 °C/1000 feet and if it reaches dewpoint — the convection or lifting condensation level — cumulus will form. They are initially maintained by a series of random rising eddies, but if developed enough can draw in surrounding moist air and maintain itself, in a steady organised upward flow, from the release of the latent heat of condensation. If the cloud has enough energy to pass the freezing level it may develop into a rain and wind storm, and possibly a CB. Refer to section 3.6.

    In most instances the air providing the water vapour for convective cloud growth comes from within the friction layer. When thermal turbulence of sufficient intensity to penetrate above the friction layer is present, and the condensation level lies above the friction layer, then isolated convective cloud — fair weather cumulus CU HUM — is formed with clear-cut bases and tops to the limit of penetration. A subsidence inversion above the condensation level may limit the vertical extent, with the cloud spreading out in broken SC. Night cooling also has the effect of spreading the cloud into broken SC. Air warmed by advection over a warm surface, particularly the sea, in a summer anticyclone provides ideal conditions for development of fair weather cumulus.

    3.2 Frictional turbulence
    An airstream flowing over ground or water produces a turbulent layer, up to 500 feet deep in light winds or 3000 feet plus in strong winds. The vertical eddies within this friction layer or boundary layer transport air from the upper level to the surface, adiabatically warmed to a temperature above that of the surface air. Similarly surface air is transported to the upper level, cooling adiabatically to temperatures below that of the upper level. Thus, as the turbulent mixing continues, the lower level is warmed and the upper level is cooled until the temperature lapse rate through the layer equals the DALR and the layer is in neutral stability — providing the air remains unsaturated. An inversion is formed at the top of the friction layer. A pre-existing inversion, e.g. a subsidence inversion, will strengthen the process. Thermal turbulence will also be present.
    The deep, turbulent mixing also has the effect of evening-out the moisture content throughout the layer and if the humidity mixing ratio is high enough a mixing condensation level will be reached within the friction layer. If the lapse rate of the layer above the friction layer is stable, then layer cloud will form with its base at the mixing condensation level and its top at the inversion. Thus the thickness of the cloud layer will vary from very thin to possibly 3000 feet.

    If the upper air layer is unstable then cloud development would not be halted at the inversion and convective cloud would probably develop. If the wind is light the layer cloud would tend to ST, otherwise SC with undulations in the lower surface continually forming, with breaks where cloud is being evaporated in the down currents. ST FRA may also form with local variations in humidity, temperature and turbulence. Cloud produced by frictional turbulence is not usually associated with precipitation except perhaps for drizzle from dense layers.

    3.3 Orographic ascent
    Orography is the branch of physical geography concerned with mountains. An airstream encountering a topographic barrier (i.e. hill, ridge, valley spur, mountain range) is forced to rise, in a broad cross-section from at or near the surface to the upper levels, and cools adiabatically. If the lift and the moisture content are adequate, condensation occurs at the lifting condensation level and cloud is formed on or above the barrier. Stratus is formed if the air is stable, whilst cumulus forms if the air is slightly unstable. If there is instability in depth, coupled with high moisture, CB may develop (refer to section 3.6). Solar heating of ridges may cause the adjacent air to be warmer than air at the same level over the valleys; thus the ridge acts as a higher-level heat source, increasing buoyancy and accentuating the mechanical lifting.

    The orographic lifting of an airstream provides gliders with the opportunity for ridge or hill soaring. Sea breezes crossing relatively small topographic barriers at the coastline (e.g. cliffs) may provide quite smooth uplift.

    Orographic cloud — cap cloud — in stable conditions tends to form continuously on the windward side of mountain ridges, but clears on the lee side. Lenticular cloud may also form a high cap above a hill when there is a layer of near saturated air aloft; orographic lifting causes condensation, and descent causes evaporation. A mountain wave may form — particularly in a sandwiched, stable layer — resulting in the formation of a series of lenticular clouds.

    3.4 Convergence and widespread ascent
    The air in the centre of a low pressure centre, trough or heat trough is lifted by convergence, as is the air in the inter-tropic convergence zone.

    The air in the broad area ahead of a cold front is lifted by the frontal action. Generally the air rises very slowly, possibly one to five feet/minute, and cools. If moist enough, the air condenses at the lifting condensation level producing extensive layers of stratus-type cloud: NS, AS, CS and CI. However active or fast-moving fronts may nose the air up much more rapidly, leading to CB development.

    4. Fog
    Fog [FG] is defined as an obscurity in the surface layers of the atmosphere that is caused by a suspension of water droplets, with or without smoke particles, and which is defined by international agreement as being associated with visibility less than 1000 metres. If the visibility is between 1000 and 5000 metres then the obscurity is mist — meteorological code BR, from the French brouillard = mist.

    Radiation fogs are the prevalent fogs in Australia, with occurrence peaking in winter. They are caused by lowering of the ground temperature through re-radiation into space of absorbed solar radiation. Radiation fogs mainly occur in moist air on cloudless nights within a high-pressure system, particularly after rainfall. The moist air closest to the colder surface will quickly cool to dewpoint with condensation occurring. As air is a poor conductor, a light wind of 2–6 knots will facilitate the mixing of the cold air throughout the surface layer, creating fog. The fog itself becomes the radiating surface in turn, encouraging further cooling and deepening of the fog. An increase in atmospheric pollution products supplies extra condensation nuclei to enhance the formation of fog; i.e. smog.

    A low-level inversion forms and the contained fog may vary from scattered pools in surface depressions to a general layer 1000 feet in depth. Calm conditions will result in a very shallow fog layer, or just dew or frost. The fog droplets sink at about 1 cm/sec. Surface winds greater than 10 knots may prevent formation of the inversion; the cooled air is mixed with the warmer air above, and so does not cool to dewpoint. If the forecast wind at 3000 feet is 25 knots or more, the low-level inversion may not form and fog is unlikely (refer to 'spread' in section 1.5). In winter, radiation fog may start to form in the evening and persist to midday — or later if the sun is cut off by higher-level cloud and/or the wind does not pick up sufficiently to break up the low-level inversion.

    Advection fog may occur when warm, moist air is carried over a surface that is cooler than the dewpoint of the air. Cooling and some turbulence in the lower layer lowers temperature to dewpoint and fog forms. Sea fogs drifting into New South Wales coastal areas are advection fogs that are formed when the sea surface temperature is lower than the dewpoint, but with a steady breeze to promote air mixing. Dewpoint can be reached by both temperature reduction and by increased water vapour content through evaporation. Advection fogs will form in valleys open to the sea when temperature falls in the evening, and when combined with a sea breeze of 5 – 15 knots to force the air upslope. Thick advection fogs may be persistent in winter, particularly under a mid-level cloud layer.

    Shallow evaporation fogs or steaming fogs result from the immediate condensation of water vapour that has just evaporated from the surface into near-saturated air. Steaming from a sun-warmed road surface after a rain shower demonstrates the process. Sea smoke or frost smoke is an evaporation fog occurring in frigid Antarctic air moving over relatively warm waters, thereby prompting evaporation into the cold air which, in turn, quickly produces saturation.

    Freezing fog is a fog composed of supercooled water droplets that freeze on contact with solid objects; e.g. parked aircraft. When near-saturated air is very cold, below –24 °C at sea level to –45 °C at 50 000 feet, the addition of only a little moisture will produce saturation. Normally, little evaporation takes place in very cold conditions but release of water vapour from engine exhausts, for instance, can quickly saturate calm air (even though the engine exhaust heat tends to lower the relative humidity) and will produce ice fog at the surface or condensation trails [contrails] at altitude. If the temperature is below –40 °C, ice crystals form directly on saturation. Contrails persist if relative humidity is high but evaporate quickly if low. Distrails occur when the engine exhaust heat of an aircraft flying through a thin cloud layer dissipates a clear trail.

    Frontal fog or rain-induced fog occurs when warm rain evaporates at surface level in light wind conditions and then condenses to form fog.

    5. Precipitation
    5.1 Rain [RA] and drizzle [DZ]
    Cloud droplets tend to fall but their terminal velocity is so low, about 0.01 metres/sec, that they are kept aloft by the vertical currents associated with the cloud construction process; but droplets will evaporate when coming into contact with the drier air outside the cloud. Some of the droplets are larger than others and consequently their falling speed is greater. Larger droplets catch up with smaller ones and merge or coalesce with them, eventually forming raindrops. Raindrops grow with the coalescence process and reach maximum diameters — in tropical conditions — of 4–7 mm before air resistance disintegrates them into smaller raindrops; this starts a self-perpetuating process. It takes about one million cloud droplets to form one raindrop.

    The terminal velocity of a 4 mm raindrop is about 9 metres/sec. Only clouds with extensive depth, 3000 feet plus, will produce rain (rather than drizzle). But very small, high clouds — generating heads — may produce trails of snow crystals, which evaporate at lower levels — fall streaks or virga.

    Drizzle forms by coalescence in stratiform clouds with depths possibly less than 1000 feet and with only weak vertical motion — otherwise the small (0.2 – 0.5 mm) drops would be unable to fall. It also requires only a short distance or a high relative humidity between the cloud base and the surface — otherwise the drops will evaporate before reaching the surface. Terminal velocity approximates 1–2 metres/sec. Light drizzle [–DZ]: visibility greater than 1000 metres Moderate drizzle [DZ]: visibility 500–1000 metres Heavy drizzle [+DZ]: visibility less than 500 metres Light rain showers [–SHRA]: precipitation rate under 2 mm/hour Moderate rain showers [SHRA]: 2–10 mm/hour Heavy rain showers[+SHRA]: more than 10 mm/hour Light rain [–RA]: under 0.5 mm/hour, individual drops easily seen Moderate rain [RA]: 0.5–4 mm/hour, drops not easily seen Heavy rain [+RA]: more than 4 mm/hour, rain falls in sheets
    Weather radar reports precipitation according to the reflectivity level: 1 – light precipitation 2 – light to moderate rain 3 – moderate to heavy rain 4 – heavy rain 5 – very heavy rain, hail possible 6 – very heavy rain and hail, large hail possible
    Scotch mist is a mixture of thick cloud and heavy drizzle on rising ground, formed in conditions of weak uplift of almost saturated stable air.

    5.2 Snow [SN]
    At cloud temperatures colder than –10 °C where both ice and supercooled liquid water exist, the saturation vapour pressure over water is greater than that over ice. Air that is just saturated with respect to the supercooled water droplets will be supersaturated with respect to the ice crystals, resulting in vapour being deposited onto the crystal (refer to section 1.5). The reduction in the amount of water vapour means that the air is no longer saturated with respect to the water droplets. To achieve saturation equilibrium again, the water droplets begin to evaporate. Thus ice crystals grow by sublimation and water droplets lessen, i.e. in mixed cloud the ice crystals grow more rapidly than the water droplets. Snow is frozen precipitation resulting from ice crystal growth, and falls in any form between small crystals and large flakes. This is known as the Bergeron-Findeison theory and probably accounts for most precipitation outside the tropics. Snow may fall to the surface or, more often, melt below the freezing level and fall as rain.

    Snowflakes are built by snow crystals colliding and sticking together in clusters of several hundred — known as aggregation. Most aggregation occurs at temperatures just below freezing, as the snow crystals tend to remain separate at colder temperatures.

    5.3 Hail and other ice forms
    The growing snow crystals acquire a fall velocity relative to the supercooled droplets. Growth also continues by collision and coalescence with supercooled droplets forming ice pellets [PE]. The process is termed accretion, or opaque riming if the freezing is instantaneous incorporating trapped air, or glazing if the supercooled water freezes more slowly as a clear layer. A similar process occurs with airframe icing. The ice pellets in turn grow by coalescing with other pellets and further accretion — these are termed hail [GR] when the diameter exceeds 5 mm. The size reached by hailstones before falling out of the cloud depends on the velocity and frequency of updraughts within the cloud. Hail is of course a hazard to aviation, particularly when it is unexpected; for example hail falling from a CB anvil can appear to fall from a clear sky. Snow grains [SG] are very small, flattened, opaque ice grains, less than 1 mm and equivalent to drizzle. Snowflakes that, due to accretion, become opaque, rounded and brittle pellets, 2 – 5 mm diameter, are called snow pellets or graupel [GS]. Sleet is transparent ice pellets less than 5 mm diameter that bounce on impact with the ground. Sleet starts as snow, partially melting into rain on descent through a warm layer, then refreezing in a cold near-surface layer. The term is sometimes applied to a snow/rain mixture or just wet snow. Diamond dust [IC] is minute airborne ice crystals that only occur under very cold (Antarctic) conditions.

    When raindrops form in cloud-top temperatures warmer than –10 °C the rain falls as supercooled drops. Such freezing rain or drizzle striking a frozen surface, or an aircraft flying in an outside air temperature [OAT] at or below zero, will rapidly freeze into glaze ice. Freezing rain is responsible for the ice storms of North America and northern Europe, but the formative conditions differ from the preceding.

    5.4 The seeder – feeder mechanism
    Any large-scale air flow over mountain areas produces, by orographic effect, ice crystals in cold cloud tops. By themselves, the falling crystals would cause only light drizzle at the ground. However, as the crystals fall through the low-level mountain top clouds they act as seed particles for raindrops that are formed by coalescing cloud droplets with the falling crystals, producing substantial orographic rainfall in mountain areas.

    Aerial cloud seeding involves introducing freezing nuclei (silver-oxide crystals with a similar structure to ice crystals) into parts of the cloud where few naturally exist, in order to initiate the Bergeron-Findeison process.

    6. Thunderstorm development
    Like CU, surface heating may provide the initial trigger to create isolated CB within an air mass but the initial lift is more likely to be provided by orographic ascent or convergence effects.

    In the formative stages of a CB, the cloud may have an updraught pulse of 1000–2000 feet/min. The rising parcel of air reaches altitudes where it is much warmer than the surrounding air, by as much as 10 °C, and buoyancy forces accelerate the parcel aloft possibly reaching speeds of 3000–7000 feet/min. Precipitation particles grow with the cloud growth. The upper levels of the cloud gain additional energy from the latent heat released from the freezing of droplets, and the growth of snow crystals and hailstones. When the growth of the particles is such that they can no longer be suspended in the updraught, then precipitation — and its associated drag downdraught — occurs.

    If the updraught path is tilted by wind shear or veer, rather than vertical, then the precipitation and its downdraught will fall away from the updraught, rather than back down through it (consequently weakening or stopping the updraught) and a co-existing updraught/downdraught may become established. An organised cell system controlling its environment and lasting several hours may evolve.

    Middle-level dry air from outside the cloud is entrained into the downdraught of an organised cell. The downdraught is further cooled by the dry inflow air evaporating some of its water and ice crystals, and tends to accelerate downwards in vertical gusts. At the same time, the downdraught maintains the higher horizontal momentum it gained at upper levels from the higher forward speed of the storm at that height. When the cold, plunging air nears the surface, the downburst spreads out in all directions as a cold gust front or squall. This is strongest at the leading edge of the storm and weakest towards the trailing edge.

    Each organised cell system contains an updraught / downdraught core. Beneath this is the outflow region containing the rain shield. The core is bounded by the downdraught gust front, a flanking line with a dark, flat base. Underneath this is the inflow region of warm, moist air. The CU and TCU generated by the inflow within the flanking line are the genesis of new cells. Within the core, the condensation of moisture from the inflow region produces rain, hail and snow and the associated downdraught to the outflow region. When the cool air outflow exceeds and finally smothers(or undercuts and chokes off) the inflow, then the storm dissipates.

    High moisture content in the low-level air with dry, mid-level air and atmospheric instability are required to maintain CB development. The amount of precipitation from a large storm is typically 200 000 tonnes but severe storms have produced 2 million tonnes.

    Anvils may take several forms: Cumuliform: forms when a very strong updraught spreads rapidly and without restriction. Back-sheared: the cloud top spreads upwind, against the high-level flow, this indicates a very strong updraught. Mushroom: a rollover or lip around the underside of an overhanging anvil, which indicates rapid expansion. Overshooting top: a dome-like protusion through the top of an anvil, which indicates a very strong updraught pulse. The overshooting top in large tropical storms has been known to develop into a 'chimney' form, towering maybe 10 000 feet into the stratosphere, with an extensive plume cloud extending downwind from its top. Such clouds transfer moisture to the stratosphere.  
    The Australian Bureau of Meteorology Web site has a storm spotters' guide.
    Parts 1 and 2 briefly describe the structure and types of thunderstorms likely to be encountered in Australia.

    For further information on clouds, fog and precipitation consult the University of Manchester's Intute, an online catalogue of internet resources in Earth sciences.

    7. Flight in cloud or without external visual references
    The human vestibular system
    When walking, a person's prime sense of orientation is provided by visual references. When vision is severely degraded, the vestibular system in the inner ears, which senses motion and gravity (thus roll, pitch and yaw), generally allows us to keep our balance when walking without using visual references. However, the vestibular system is not designed for high speed or angular motion, and cannot be used as an in-flight back-up system; i.e. you cannot close your eyes and continue to fly straight and level. Motion of the fluid within the ears' semicircular canals is affected by inertia and will feed quite erroneous prompts to the brain, resulting in various types and levels of vertigo.

    For example, without the external visual references of clear sky, terrain or a horizon, forward deceleration tends to give a pitching-down sensation whilst forward acceleration gives a pitching-up sensation. Once settled into a constant rate turn, the sensation is of not turning at all; but when the turn is halted, the sensation is then of turning in the opposite direction. In addition, the vestibular system will not detect slow rates of bank, so that if the aircraft is banking at the rate of one or two degrees per second the vestibular system will not send any prompts to the brain — it will consider the aircraft is still flying straight and level, while any associated speed changes may provide contrary sensations. For example, if the aircraft is slowly banking and accelerating in a descending turn, the sensation may well be one of pitching-up.

    Spatial disorientation
    Aircraft accidents caused by spatial disorientation are usually fatal and occur when VFR flight is continued in adverse visibility conditions — cloud, fog, smoke, haze, showers, oncoming darkness and combinations thereof. Pilots who have not been trained to fly solely by visual reference to the flight instruments in a 'blind flying' panel will soon find themselves experiencing spatial disorientation should they, inadvertently or deliberately, enter cloud where the external visual references — by which they normally orient themselves in visual meteorological conditions — are lost. The same applies to any atmospheric condition or in adverse weather where the visual references (horizon [principally], terrain and clear sky) are lost or just significantly reduced — smoke from bushfires or extensive burning of sugar cane, for example.

    Even a pilot who is well experienced in flying in instrument meteorological conditions may occasionally experience a phenomenon called 'the leans'. This usually occurs when the aircraft has been inadvertently allowed to slowly bank a few degrees and the pilot then makes a quick correction to level the wings. The vestibular system doesn't register the initial bank but does register the wing levelling as an opposite direction bank (away from a wings-level attitude) — and the pilot's brain produces a leaning sensation while also perceiving from the instrument readings that the aircraft is flying straight and level. The reaction — which can persist for quite a while — may be for the pilot to lean sideways in her/his seat so that everything feels right!

    Read the section titled 'Pressing on in deteriorating conditions' in the Flight Planning and Navigation Guide.

    For more information on the vestibular functions and effects, google the terms 'vestibular spatial disorientation' in a web search.


    Aviation Terms

    By Admin, in Reference Items,

    This list of Aviation Terms contains those that are most frequently used. To have one added to the list please let me know...thanks
    AGL - Above Ground Level, as a measurement of altitude above a specific land mass, and differentiated from MSL. ADF - Automatic Direction Finding via automated radio. ADI - Attitude direction indicator. Shows the roll and pitch of the aircraft. AFCS - Automatic flight control system that provides inputs to the fight controls to assist the pilot in maneuvering and handling the aircraft. AFT - Referring to the rear of the aircraft. AI - Altitude indicator. Displays the aircraft's altitude above sea level. Aileron - The movable areas of a wingform that control or affect the roll of an aircraft by working opposite one another-up-aileron on the right wing and down-aileron on the left wing. AIM - Airman's Information Manual - A primary FAA publication whose purpose is to instruct airmen about operating in the US airspace system. ADC - Air Data Computer - A primary sensor-based navigation data source. AGR - Air-Ground Ranging - Straight-line distance from the aircraft to a point on the ground. ATC - Air Traffic Control - A service operated by the appropriate authority to promote the safe, orderly, and expeditious flow of air traffic. Airfoil - The shape of the wing when looking at its profile. Usually a teardrop shape. Airframe - The fuselage, booms, nacelles, cowlings, fairings, and airfoil surfaces of an aircraft. Airspeed - The speed of an aircraft relative to its surrounding air mass. See: calibrated airspeed; indicated airspeed; true airspeed. Airspeed Indicator - An onboard instrument which registers velocity through the air, usually in knots. Different from ground speed. AIS - Aeronautical Information Service. ALS - Approach light system. A lighting system installed on the approach end of an airport runway and consists of a series of lightbars, strobe lights, or a combination of the two that extends outward from the runway end. ALT - Short term for Altitude. Altimeter - An onboard instrument which senses air pressure in order to gauge altitude. Altimeter Setting - The barometric pressure reading used to adjust a pressure altimeter for variations in existing atmospheric pressure. Altitude - Height of an aircraft, usually with respect to the terrain below. Angle of Attack - The angle between the chord line of the wing of an aircraft and the relative wind. Annual - Mandatory inspection of airframe and power plant that occurs every 12 months. AO - Aircraft Operator. AOPA - Aircraft Owner and Pilot's Association. APP - Approach (Control). Approach Speed - The recommended speed contained in aircraft manuals used by pilots when making an approach to landing. ARCID - Aircraft Identification. ATA - Actual Time of Arrival. As opposed to ETA (Estimated Time of Arrival) used in filing a flight plan. ATD - Actual Time of Departure. As opposed to ETD (Estimated Time of Departure) used in filing a flight plan. ATIS - Automated Terminal Information Service usually containing vital information on wind direction, velocity, pressure readings, and active runway assignment for that particular airport. Attitude - The primary aircraft angles in the state vector; pitch, roll, and yaw. Attitude Indicator - A vacuum powered instrument which displays pitch and roll movement about the lateral and longitudinal axes. ADF - Automatic Direction Finding - A basic guidance mode, providing lateral guidance to a radio station. Equipment that determines bearing to a radio station. Autopilot - A method of an automatic flight control system which controls primary flight controls to meet specific mission requirements. Autorotation - A rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air when the rotorcraft is in motion. AVGAS - Aviation Gasoline (piston aircraft fuel). Bernoulli Effect - Airflow over the upper surface of an airfoil causes suction (lift) because the airstream has been speeded up in relation to positive pressure of the airflow on the lower surface. CAS - Calibrated Airspeed - The indicated airspeed of an aircraft, corrected for position and instrument error. CAS is equal to true airspeed in standard atmosphere at sea level. Camber - The convex or concave curvature of an airfoil. CAT - Clear Air Turbulance. CAVU - Ceiling and Visibility Unlimited; ideal flying weather. Ceiling - The heights above the earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as "broken," "overcast," or "obscured". CG - Center of Gravity - The longitudinal and lateral point in an aircraft where it is stable; the static balance point. Chord - The measurable distance between the leading and trailing edges of a wingform. CTAF - Common Traffic Advisory Frequency - A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications. Controlled Airspace - An airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification. Controlled airspace is a generic term that covers Class A, B, C, D, and E airspace. Crabbing - A rudder-controlled yawing motion to compensate for a crosswind in maintaining a desired flight path, as in a landing approach. Dead Reckoning - The process of estimating one's current position based upon a previously determined position, or fix, and advancing that position based upon known speed, elapsed time, and course. Deadstick - Descending flight with engine and propeller stopped. Departure Stall - A stall in the takeoff configuration with power. Deviation (Magnetic) - The error of a Magnetic Compass due to inherent magnetic influences in the structure and equipment of an aircraft. Directional Gyro - A panel instrument providing a gyroscopic reading of an aircraft's compass heading. DME - Distance Measuring Equipment, a radio navigation device that determines an aircraft's distance from a given ground station, as well as its groundspeed and time to/from the station. Drag - The resisting force exerted on an aircraft in its line of flight opposite in direction to its motion. Dry Weight - The weight of an engine exclusive of any fuel, oil, and coolant. Elevator - The movable part of a horizontal airfoil which controls the pitch of an aircraft, the fixed part being the Stabilzer. ETA - Estimated time of arrival. ETD - Estimated time of departure. FBO - Fixed-Base Operator. A commercial operator supplying fuel, maintenance, flight training, and other services at an airport. FAR - Federal Air Regulations. Flap - A movable, usually hinged airfoil set in the trailing edge of an aircraft wing, designed to increase lift or drag by changing the camber of the wing or used to slow an aircraft during landing by increasing lift. Flare - A control wheel maneuver performed moments before landing in which the nose of an aircraft is pitched up to minimize the touchdown rate of speed. Flight Envelope - An aircraft's performance limits, specifically the curves of speed plotted against other variables to indicate the limits of speed, altitude, and acceleration that a particular aircraft cannot safely exceed. Flight Plan - Specified information relating to the intended flight of an aircraft, filed orally or in writing with an FSS or an ATC facility. FSS - Flight Service Station - Air traffic facilities which provide pilot briefing, enroute communications and VFR search and rescue services, and assist lost aircraft. Fuselage - An aircraft's main body structure housing the flight crew, passengers, and cargo and to which the wings, tail and, in most single-engined airplanes, engine are attached. GA - General Aviation - That portion of civil aviation which encompasses all facets of aviation except air carriers holding a certificate of public convenience and necessity from the Civil Aeronautics Board and large aircraft commercial operators. Glass Cockpit - Said of an aircraft's control cabin which has all-electronic, digital and computer-based, instrumentation. Glider - An unpowered aircraft capable of maintaining altitude only briefly after release from tow, then gliding to earth. Glide Scope - (1) The angle between horizontal and the glide path of an aircraft. (2) A tightly-focused radio beam transmitted from the approach end of a runway indicating the minimum approach angle that will clear all obstacles; one component of an instrument landing system (ILS). GPS - Global Positioning System; satellite-based navigation, rapidly replacing dead reckoning methods. Gross Weight - The total weight of an aircraft when fully loaded, including fuel, cargo, and passengers; aka Takeoff Weight. Ground Control - Tower control, by radioed instructions from air traffic control, of aircraft ground movements at an airport. Ground Effect - Increased lift generated by the interaction between a lift system and the ground when an aircraft is within a wingspan distance above the ground. It affects a low-winged aircraft more than a mid- or high-winged aircraft because its wings are closer to the ground. Ground Speed - The actual speed that an aircraft travels over the ground its "shadow speed"; it combines the aircraft's airspeed and the wind's speed relative to the aircraft's direction of flight. IFR - Instrument Flight Rules, governing flight under instrument meteorological conditions. ILS - Instrument Landing System. A radar-based system allowing ILS-equipped aircraft to find a runway and land when clouds may be as low as 200' (or lower for special circumstances). IAS - Indicated Air Speed - A direct instrument reading obtained from an air speed indicator uncorrected for altitude, temperature, atmospheric density, or instrument error. Compare calibrated airspeed and true airspeed. IMC - Instrument Meterological Conditions - Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than minimal specified for visual meteorological conditions (VMC). Knot - One nautical mile, about 1.15 statute miles (6,080'); eg: 125kts = 143.9mph. Lift - The force exerted on the top of a moving airfoil as a low-pressure area [vacuum] that causes a wingform to rise. airfoils do not "float" on air, as is often assumed - like a boat hull floats on water - but are "pulled up" (lifted) by low air pressures trying to equalize. Lift-Drag Ratio - The lift coefficient of a wing divided by the drag coefficient, as the primary measure of the efficiency of an aircraft; aka L/D ratio. Liquid Compass - A non-electronic, calibratable compass floating in a liquid as a panel instrument; aka wet compass. Load Factor - The proportion between lift and weight commonly seen as g (sometimes capitalized) - a unit of force equal to the force of gravity times one. LORAN - Long Range Navigation System - Utilizes timing differences between multiple low-frequency transmissions to provide accurate latitude/longitude position information to within 50'. LTA - Lighter-than-air craft, generally referring to powered blimps and dirigibles, but often also includes free balloons. Magnetic Compass - The most common liquid-type compass, capable of calibration to compensate for magnetic influences within the aircraft. Magnetic Course - Compass course + or - deviation. Magnetic North - The magnetic North pole, located near 71° North latitude and 96° West longitude, that attracts a magnetic compass which is not influenced by local magnetic attraction. MAG - Magneto - An accessory that produces and distributes a high-voltage electric current for ignition of a fuel charge in an internal combustion engine. MSL - Mean Sea Level. The average height off the surface of the sea for all stages of tide; used as a reference for elevations, and differentiated from AGL. METAR - Acronym in FAA pilot briefings and weather reports simply means an "aviation routine weather report". NDB - Non Directional Beacon - An LF, MF, or UHF radio beacon transmitting non-directional signals whereby the pilot of an aircraft equipped with direction finding equipment can determine his bearing to or from the radio beacon and "home" on or track to or from the station. PAR - Precision Approach Radar, a ground-radar-based instrument approach providing both horizontal and vertical guidance. Pattern - The path of aircraft traffic around an airfield, at an established height and direction. At tower-controlled fields the pattern is supervised by radio (or, in non-radio or emergency conditions by red and green light signals) by air traffic controllers. Flying an entire pattern is called a 'Circuit'. PIC - Pilot in Command - The pilot responsible for the operation and safety of an aircraft during flight time. Pitch - Of the three axes in flight, this specifies the vertical action, the up-and-down movement. Pitot Tube - More accurately but less popularly used, Pitot-Static Tube, a small tube most often mounted on the outward leading edge of an airplane wing (out of the propeller stream) that measures the impact pressure of the air it meets in flight, working in conjuction with a closed, perforated, coaxial tube that measures the static pressure. Roll - Of the three axes in flight, this specifies the action around a central point. Rotorcraft - A heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or more rotors. Includes helicopters and gyroplanes. Rudder - The movable part of a vertical airfoil which controls the YAW of an aircraft; the fixed part being the fin. Scud - A low, foglike cloud layer. Service Ceiling - The height above sea level at which an aircraft with normal rated load is unable to climb faster than 100' per minute under Standard Air conditions. Sideslip - A movement of an aircraft in which a relative flow of air moves along the lateral axis, resulting in a sideways movement from a projected flight path, especially a downward slip toward the inside of a banked turn. Sink, Sinking Speed - The speed at which an aircraft loses altitude, especially in a glide in still air under given conditions of equilibrium. Skid - Too shallow a bank in a turn, causing an aircraft to slide outward from its ideal turning path. Slip - Too steep a bank in a turn, causing an aircraft to slide inward from its ideal turning path. Slipstream - The flow of air driven backward by a propeller or downward by a rotor. Squawk Code - A four-digit number dialed into his transponder by a pilot to identify his aircraft to air traffic controllers. Stabilizer - The fixed part of a horizontal airfoil that controls the pitch of an aircraft; the movable part being the elevator. Stall - (1) Sudden loss of lift when the angle of attack increases to a point where the flow of air breaks away from a wing or airfoil, causing it to drop. (2) A maneuver initiated by the steep raising of an aircraft's nose, resulting in a loss of velocity and an abrupt drop. TAS - True Air Speed - True Air Speed. Because an air speed indicator indicates true air speed only under standard sea-level conditions, true air speed is usually calculated by adjusting an Indicated Air speed according to temperature, density, and pressure. Thrust - The driving force of a propeller in the line of its shaft or the forward force produced in reaction to the gases expelled rearward from a jet or rocket engine. Opposite of drag. Torque - A twisting, gyroscopic force acting in opposition to an axis of rotation, such as with a turning propeller; aka Torsion. Touch-and-Go - Landing practice in which an aircraft does not make a full stop after a landing, but proceeds immediately to another take-off. Transponder - An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position information than would be possible with "passive" radar; may also provide air traffic control with an aircraft's altitude. Trim Tab - A small, auxiliary control surface in the trailing edge of a wingform, adjustable mechanically or by hand, to counteract ("trim") aerodynamic forces on the main control surfaces. Turn & Bank Indicator - Primary air-driven gyro instrument, a combined turn indicator and lateral inclinometer to show forces on an aircraft in banking turns. Also referred to as "needle & ball" indicator, the needle as the gyro's pointer and a ball encased in a liquid-filled, curved tube. Uncontrolled Airspace - Class G Airspace; airspace not designated as Class A, B, C, D or E. UNICOM - Universal Communication - A common radio frequency (usually 121.0 mHz) used at uncontrolled (non-tower) airports for local pilot communication. Useful Load - The weight of crew, passengers, fuel, baggage, and ballast, generally excluding emergency or portable equipment and ordnance. V - Velocity - Used in defining air speeds, listed below: VA = Maneuvering Speed (max structural speed for full control deflection) VD = Max Dive Speed (for certification only) VFE = Max Flaps Extended Speed VLE = Max Landing Gear Extended Speed VLO = Max Landing Gear Operation Speed VNE = Never Exceed Speed VNO = Max Structural Cruising Speed VS0 = Stalling Speed Landing Configuration VS1 = Stalling Speed in a specified Configuration VX = Best Angle of Climb Speed VXSE = Best Angle of Climb Speed, one engine out VY = Best Rate of Climb Speed VYSE = Best Rate of Climb Speed, one engine out VASI - Visual Approach Slope Indicator - A system of lights on the side of an airport runway that provides visual descent guidance information during the approach to a runway. Venturi Tube - A small, hourglass-shaped metal tube, usually set laterally on a fuselage in the slipstream to create suction for gyroscopic panel instruments. Now outdated by more sophisticated means. VFR - Visual Flight Rules that govern the procedures for conducting flight under visual conditions. The term is also used in the US to indicate weather conditions that are equal to or greater than minimum VFR requirements. Also used by pilots and controllers to indicate a specific type of flight plan. VMC - Visual Meteorological Conditions - Expressed in terms of visibility, distance from clouds, and ceiling equal to or better than specified minima. VOR - VHF OmniRange - A ground-based navigation aid transmitting very high-frequency (VHF) navigation signals 360° in azimuth, on radials oriented from magnetic nort. The VOR periodically identifies itself by Morse Code and may have an additional voice identification feature. Voice features can be used by ATC or FSS for transmitting information to pilots. VSI - Vertical Speed Indicator. A panel instrument that gauges rate of climb or descent in feet-per-minute (fpm). Also called the Rate Of Climb Indicator. Yaw - Of the three axes in flight, this specifies the side-to-side movement of an aircraft on its vertical axis, as in skewing. Yoke - The control wheel of an aircraft, akin to a automobile steering wheel.


    ATC Phrases

    By Admin, in Reference Items,

    The following are the most common ATC phrases
    "Cleared to taxi"
    When told by ground control or tower that you are cleared to taxi, the controller has given you instruction to taxi along taxiway centerlines according to taxiway markings. It is important to repeat all controller instructions and runway crossing instructions, as you may be told to "hold short" of a specific runway and wait for further instructions.
    "Position and hold" or "Line up and Wait" (AUS)
    The tower expects you to taxi onto runway centerline and maintain a stopped position while the aircraft in front of you gains separation or clears the runway. It is important that, prior to crossing the hold-short lines, you verify your instructions, verify runway of use, and scan extended final for traffic.
    "Cleared for takeoff"
    The tower controller is the only authority to clear you for takeoff at a controlled airfield. Repeat back your takeoff clearance and call sign, as well as scan final for traffic. The tower may request other specific instructions, so listen closely to your takeoff clearance.
    "Enter closed traffic"
    The tower has acknowledged the pilot's intention to perform successive operations involving takeoffs and landings or low approaches where the aircraft does not exit the traffic pattern.
    "Cleared for the option"
    When you are cleared for the option you have been given permission to either do a touch-and-go, make a low approach, missed approach, stop and go, or full-stop landing. If requesting this clearance, the pilot should do so upon establishing downwind on a VFR traffic pattern.
    "Cleared touch-and-go"
    When authorized by the tower, the touch-and-go procedure allows the pilot to land on the runway, reconfigure the airplane and perform a takeoff to re-enter the traffic pattern. If requesting this approach the pilot should do so upon establishing downwind on a VFR traffic pattern.
    "Cleared low approach"
    A low approach clearance allows the pilot to perform a simulated emergency landing or normal landing down to the runway environment (100' AGL) and then perform a go-around to re-enter or depart the pattern. If requesting this approach you should do so upon establishing downwind on a VFR traffic pattern.
    "Cleared stop-and-go"
    A stop-and-go clearance allows the pilot to land on the runway, come to a full stop, and then takeoff on the remaining length of runway. The pilot must be aware of runway lengths and takeoff distance requirements. This procedure can be beneficial in keeping costs lower when performing night currency. If requesting this clearance the pilot should do so upon establishing downwind on a VFR traffic pattern.
    "Cleared to land"
    When given clearance to land the tower has authorized you to land on the runway in use. The phrase "cleared to land" gives you immediate use of that runway, unless the tower advises that you are in sequence for landing ("number two to land, number three, etc..."). After advising approach or tower that you are inbound for landing at your destination you do not have to make any further request for clearance to land.
    The land-and-hold-short procedure requires the pilot to perform an accurate landing on the runway so that the pilot can stop the aircraft before reaching an intersecting runway, intersecting taxiway, or construction area. If you are unable to comply with landand-hold-short operations, you may request clearance for a different runway.
    "Make Short Approach"
    Used by ATC to have a pilot to alter their traffic pattern so as to make a short final approach. If unable to execute a short approach, simply tell the ATC so.
    "Parking with me"
    Under normal conditions you would exit the runway at the first available taxiway, stop the aircraft after clearing the runway, and call ground control for instructions if you have not already received them. If the controller says "parking with me", he or she has given you clearance to taxi to your destination.
    "Caution: wake turbulence"
    This call from ATC advises the pilot of the potential for encountering wake turbulence from departing or arriving aircraft.
    "Frequency change approved"
    You've reached the edge of the controller's airspace and may change your radio to your next frequency.
    "Proceed direct"
    You may turn to the direct heading of your destination (often followed by this heading). Usually used by ATC once you've been vectored clear of other traffic in the area.
    "Report position"
    The controller wants to pinpoint your position relative to the airport. You should report altitude, distance, and direction. For example: "8081G is five miles southwest of the airport at one thousand two hundred feet"
    ATC would like you to hurry up whatever it is that you're doing; taking off, landing, climbing, descending, or taxiing to your destination.
    ATC request for a pilot to use his aircraft transponder identification feature (usually an IDENT button). This helps the controller to confirm an aircraft identity and position.
    Followed by a squawk code or function button on the transponder. ATC issues individual squawk codes to all aircraft within radar service in order to differentiate traffic.
    "Go around"
    Pilots receiving this transmission should abandon their approach to landing. Additional instructions from ATC may then follow. Unless otherwise instructed, VFR aircraft executing a go around should overfly the runway while climbing to pattern altitude, then enter the traffic pattern by way of the crosswind leg.
    "Watch for Traffic..."
    Usually followed by the direction and distance of the traffic, you should immediately scan for it with "Looking for traffic" and report back to the controller whether you have the aircraft in sight or not.
    "Extend Downwind"
    While this may seem obvious, the controller wants you to continue straight on your downwind until he or she tells you to turn base (often followed by "I'll call your base"). In all likelyhood you're going to have a long final. Keep course and scan for other traffic.


    NOTAM - how to read

    By Admin, in Reference Items,

    Birth of a NOTAM
    NOTAM start life as messages on the Aeronautical Fixed System (AFS). They are received centrally at the UK NOTAM office at London Heathrow from originators within the UK and from foreign NOTAM offices. AIS staff check and edit the NOTAM if necessary and they are then placed in the transmit queue for transmission to all UK NOTAM recipients. These include ATC offices, some airlines, briefing services etc.

    There is no central world-wide NOTAM database, databases are built up individually by users from the incoming message stream.

    ICAO NOTAM format
    The format of NOTAM is defined in Annex 15 to the International Convention on Civil Aviation. An explanation of the format can be found here. Here is a typical NOTAM and its decode.

    A1484/02 NOTAMN
    Q) EGTT/QMRXX/IV/NBO/A/000/999/5129N00028W005
    A) EGLL
    B) 0208231540
    C) 0210310500 EST

    Notam Decoder
    A1484/02 - one letter to indicate the Series, a 4-digit NOTAM number followed by a stroke and two digits to indicate the year.

    NOTAMN - Suffix N Indicates this is a new NOTAM. Other options are R for NOTAM replacing another or C for one cancelling another.

    Q) EGTT/QMRXX/IV/NBO/A/000/999/5129N00028W005

    This is the "Q" or qualifier line, it always starts Q) and contains the following fields, each separated by a stroke.

    FIR (here EGTT, London FIR)

    NOTAM Code, a 5 letter code starting with Q, defined in Annexe 15. Here QMR indicates that it concerns a Runway. XX indicates that remaining detail is in Plain Language. In this particular case the text shows that certain runway lighting is unavailable. Strictly speaking under ICAO rules this should have appeared as separate NOTAM for each type of lighting. QLCAS is the code for centreline lighting u/s QLZAS is the code for Touch Down Zone lighting u/s and QLAAS is the code for Approach Lighting u/s (note in all cases AS indicates unserviceable). The use of QMRXX here is a sensible compromise that reduces the number of NOTAM from three to one. A full list of codes is included in ICAO document 8126 (Aeronautical Information Services Manual).

    IV - Indicates that this is significant for IFR and VFR traffic

    NBO - indicates for immediate attention of aircraft operators, for inclusion in PIB's and Operationally significant for IFR flights

    A - Indicates scope, here Aerodrome, others are E (en-route) or W (nav warning)

    000/999 - lower and upper limits expressed as a flight level. In this case it has been left as the default as it is not applicable.

    5129N00028W005 - Indicates the geographical centre and radius of influence, always this number of digits. In this case the radius is 5 n.m.

    A) EGLL - ICAO indicator of the aerodrome or FIR (London Heathrow) can include more than one FIR

    B) 0208231540 - Date/time group (UTC) when this NOTAM becomes effective

    C) 0210310500 EST - Date/time group (UTC) when the NOTAM ceases to be effective. Note "EST" means "estimated" (NOT Eastern Standard Time!). All NOTAM with EST remain in force until cancelled or replaced.

    E) RWY 09R/27L DUE WIP NO CENTRELINE, TDZ OR SALS LIGHTING AVBL - text of the notam using ICAO abbreviations.

    Decode of this is "Runway 09/27 due to work in progress no centreline, touchdown zone or simple approach lighting system available"

    Here's the whole thing again
    A1484/02 NOTAMN
    Q) EGTT/QMRXX/IV/NBO/A/000/999/5129N00028W005
    A) EGLL
    B) 0208231540
    C) 0210310500 EST

    and here's the same thing as it appears in the PIB produced by ANAIS
    AGA : FROM 02/08/23 15:40 TO 02/10/31 05:00 EST A1484/02

    You can see that the Q line is omitted entirely, A) has been stripped out because it appears as the header to the section and B) and C) have been reformatted and placed in the first line. AGA has been derived from the Q Code "QMR" (see Annex 15)

    This appendix is to be used to interpret the contents of coded international NOTAM's.
    A NOTAM code group contains five letters. The first letter is always the letter "Q'' to indicate a code abbreviation for use in the composition of NOTAM's. The second and third letters identify the subject being reported. (See Second and Third Letter Decode Tables). The fourth and fifth letters identify the status of operation of the subject being reported. (See Fourth and Fifth Letter Decode Tables).  
    AGA Lighting Facilities (L)
    Uniform Abbreviated Phraseology
    Approach lighting system (specify runway and type)
    apch lgt
    Aerodrome beacon
    Runway center line lights (specify runway)
    rwy centreline lgt
    Landing direction indicator lights
    ldi lgt
    Runway edge lights (specify runway)
    rwy edge lgt
    Sequenced flashing lights (specify runway)
    sequenced flg lgt
    High intensity runway lights (specify runway)
    high intst rwy lgt
    Runway end identifier lights (specify runway)
    rwy end id lgt
    Runway alignment indicator lights (specify runway)
    rwy alignment indicator lgt
    Category II components of approach lighting system (specify runway)
    category II components apch lgt
    Low intensity runway lights (specify runway)
    low intst rwy lgt
    Medium intensity runway lights (specify runway)
    medium intst rwy lgt
    Precision approach path indicator (PAPI) (specify runway)
    All landing area lighting facilities
    ldg area lgt fac
    Stopway lights (specify runway)
    swy lgt
    Threshold lights (specify runway)
    thr lgt
    Visual approach slope indicator system (specify type and runway)
    Heliport lighting
    heliport lgt
    Taxiway centre line lights (specify taxiway)
    twy centreline lgt
    Taxiway edge lights (specify taxiway)
    twy edge lgt
    Runway touchdown zone lights (specify runway)
    rwy tdz lgt
    AGA Movement and Landing Area (M)
    Uniform Abbreviated Phraseology
    Movement area
    mov area
    Bearing strength (specify part of landing area or movement area)
    bearing strength
    Clearway (specify runway)
    Declared distances (specify runway)
    declared dist
    Taxiing guidance system
    tax guidance system
    Runway arresting gear (specify runway)
    rwy arst gear
    Parking area
    prkg area
    Daylight markings (specify threshold, centre line, etc.)
    day markings
    Aircraft stands (specify)
    acft stand
    Runway (specify runway)
    Stopway (specify runway)
    Threshold (specify runway)
    Runway turning bay (specify runway)
    rwy turning bay
    Strip (specify runway)
    Taxiway(s) (specify)
    AGA Facilities and Services (F)
    Uniform Abbreviated Phraseology
    Braking action measurement equipment (specify type)
    ba measurement eqpt
    Ceiling measurement equipment
    ceiling measurement eqpt
    Docking system (specify AGNIS, BOLDS, etc.)
    dckg system
    Fire fighting and rescue
    fire and rescue
    Ground movement control
    gnd mov ctl
    Helicopter alighting area/platform
    hel alighting area
    Landing direction indicator
    Meteorological service (specify type)
    Fog dispersal system
    fog dispersal
    Snow removal equipment
    snow removal eqpt
    Transmissometer (specify runway and, where applicable, designator(s) of transmissometer(s))
    Fuel availability
    fuel avbl
    Wind direction indicator
    COM Communications and Radar Facilities (C)
    Uniform Abbreviated Phraseology
    Air/ground (specify service and frequency)
    a/g fac
    En route surveillance radar
    Ground controlled approach system (GCA)
    Selective calling system (SELCAL)
    Surface movement radar
    Precision approach radar (PAR) (specify runway)
    Surveillance radar element of precision approach radar system (specify wavelength)
    Secondary surveillance radar (SSR)
    Terminal area surveillance radar (TAR)
    COM Instrument and Microwave Landing System (I)
    Uniform Abbreviated Phraseology
    DME associated with ILS
    ils dme
    Glide path (ILS) (specify runway)
    ils gp
    Inner marker (ILS) (specify runway)
    ils im
    Localizer (ILS) (specify runway)
    ils liz
    Middle marker (ILS) (specify runway)
    ils mm
    Outer marker (ILS) (specify runway)
    ils om
    ILS Category I (specify runway)
    ils I
    ILS Category II (specify runway)
    ils II
    ILS Category III (specify runway)
    ils III
    Microwave landing system (MLS) (specify runway)
    Locator, outer (ILS) (specify runway)
    ils lo
    Locator, middle (ILS) (specify runway)
    ils lm
    COM Terminal and En Route Navigation Facilities (N)
    Uniform Abbreviated Phraseology
    All radio navigation facilities (except...)
    all rdo nav fac
    Nondirectional radio beacon
    Distance measuring equipment (DME)
    Fan marker
    fan mkr
    Locator (specify identification)
    Direction finding station (specify type and frequency)
    RAC Airspace Organization (A)
    Uniform Abbreviated Phraseology
    Minimum altitude (specify en route/crossing/safe)
    mnm alt
    Class B, C, D, or E Surface Area
    Air defense identification zone (ADIZ)
    Control area (CTA)
    Flight information region (FIR)
    Upper control area (UTA)
    Minimum usable flight level
    mnm usable fl
    Area navigation route
    rnav route
    Oceanic control area (OCA)
    Reporting point (specify name or Coded designator)
    ATS route (specify)
    ats route
    Class B Airspace
    Upper flight information region (UIR)
    Upper advisory area (UDA)
    Intersection (INT)
    Aerodrome traffic zone (ATZ)
    RAC Air Traffic and VOLMET Services (S)
    Uniform Abbreviated Phraseology
    Automatic terminal information service (ATIS)
    ATS reporting office
    Area control centre (ACC)
    Flight information service (FIS)
    Aerodrome flight information service (AFIS)
    Flow control centre
    flow ctl centre
    Oceanic area control centre (OAC)
    Approach control service (APP)
    Flight service station (FSS)
    Aerodrome control tower (TWR)
    Upper area control centre (UAC)
    VOLMET broadcast
    Upper advisory service (specify)
    advisory ser
    RAC Air Traffic Procedures (P)
    Uniform Abbreviated Phraseology
    Standard instrument arrival (STAR) (specify route designator)
    Standard VFR arrival std vfr arr PC
    Contingency procedures contingency proc PD
    Standard instrument departure (SID) (specify route designator)
    Standard VFR departure
    std vfr dep PF
    Flow control procedure
    flow ctl proc
    Holding procedure
    hldg proc
    Instrument approach procedure (specify type and runway)
    inst apch proc
    Obstacle clearance limit (specify procedure)
    VFR approach procedure vfr apch proc PM
    Aerodrome operating minima (specify procedure and amended minimum)
    opr minima
    Noise operating restrictions noise opr restrictions PO
    Obstacle clearance altitude
    Obstacle clearance height
    Radio failure procedure
    radio failure proc
    Transition altitude
    transition alt
    Missed approach procedure (specify runway)
    missed apch proc
    Minimum holding altitude (specify fix)
    mnm hldg alt
    ADIZ procedure
    adiz proc
    Navigation Warnings: Airspace Restrictions (R)
    Uniform Abbreviated Phraseology
    Airspace reservation (specify)
    airspace reservation
    Danger area (specify national prefix and number)
    Overflying of ... (specify)
    Prohibited area (specify national prefix and number)
    Restricted area (specify national prefix and number)
    Temporary restricted area
    tempo restricted
    Navigation Warnings: Warnings (W)
    Uniform Abbreviated Phraseology
    Air display
    air display
    Captive balloon or kite
    captive balloon or kite
    Demolition of explosives
    demolition of explosives
    Exercises (specify)
    Air refueling
    air refueling
    Glider flying
    glider flying
    Banner/target towing
    banner/target towing
    Ascent of free balloon
    ascent of free balloon
    Missile, gun or rocket firing
    Parachute jumping exercise (PJE)
    Burning or blowing gas
    burning or blowing gas
    Mass movement of aircraft
    mass mov of acft
    Formation flight
    formation flt
    model flying
    model flying
    Other Information (O)
    Uniform Abbreviated Phraseology
    Aeronautical information service
    Obstacle (specify details)
    Aircraft entry requirements
    acft entry rqmnts
    Obstacle lights on ... (specify)
    obst lgt
    Rescue coordination centre
    Availability (A)
    Uniform Abbreviated Phraseology
    Withdrawn for maintenance
    withdrawn maint
    Available for daylight operation
    avbl day ops
    Flight checked and found reliable
    fltck okay
    Operating but ground checked only, awaiting flight check
    opr awaiting fltck
    Hours of service are now
    hr ser
    Resumed normal operations
    Military operations only
    mil ops only
    Available for night operation
    avbl night ops
    Available, prior permission required
    avbl ppr
    Available on request
    avbl o/r
    Not available (specify reason if appropriate)
    not avbl
    Completely withdrawn
    Previously promulgated shutdown has been cancelled
    promulgated shutdown cnl
    Changes (C)
    Uniform Abbreviated Phraseology
    Operating frequency(ies) changed to
    freq change
    Downgraded to
    downgraded to
    Identification or radio call sign changed to
    ident change
    Operating on reduced power
    opr reduced pwr
    Temporarily replaced by
    tempo rplcd by
    On test, do not use
    on test, do not use
    Hazard Conditions (H)
    Uniform Abbreviated Phraseology
    Braking action is ...
    ba is




    Braking coefficient is ... (specify measurement device used)
    brkg coefficient is
    Covered by compacted snow to depth of
    cov compacted snow depth
    Covered by dry snow to a depth of
    cov dry snow depth
    Covered by water to a depth of
    cov water depth
    Totally free of snow and ice
    free of snow and ice
    Grass cutting in progress
    grass cutting
    Hazard due to (specify)
    hazard due
    Covered by ice
    cov ice
    Launch planned ... (specify balloon flight identification or project Code name, launch site, planned period of launch(es)_date/time, expected climb direction, estimate time to pass 18,000 m (60,000 ft), together with estimated location)
    launch plan
    Migration in progress
    migration inpr
    Snow clearance completed
    snow clr cmpl
    Marked by
    marked by
    Covered by wet snow or slush to a depth of
    cov wet snow depth
    Obscured by snow
    obscured by snow
    Snow clearance in progress
    snow clr inpr
    Operation cancelled ... (specify balloon flight identification or project Code name)
    opr cnl
    Standing water
    standing water
    Sanding in progress
    Approach according to signal area only
    apch according signal area only
    Launch in progress ... (specify balloon flight identification or project Code name, launch site, date/time of launch(es), estimated time passing 18,000 m (60,000 ft), or reaching cruising level if at or below 18,000 m (60,000 ft), together with estimated location, estimated date/time of termination of the flight, and planned location of ground contact when applicable)
    launch inpr
    Work completed
    work cmpl
    Work in progress
    Concentration of birds
    bird concentration
    Snow banks exist (specify height)
    snow banks hgt
    Covered by frozen ruts and ridges
    cov frozen ruts and ridges
    Limitations (L)
    Uniform Abbreviated Phraseology
    Operating on auxiliary power supply
    opr aux pwr
    Reserved for aircraft based therein
    reserved for acft based therein
    Operating without auxiliary power supply
    opr without aux pwr
    Interference from
    interference from
    Operating without identification
    opr without ident
    Unserviceable for aircraft heavier than
    u/s acft heavier than
    Closed to IFR operations
    clsd ifr ops
    Operating as a fixed light
    opr as f lgt
    Usable for length of...and width of...
    usable length/width
    Closed to all night operations
    clsd night ops
    Prohibited to
    prohibited to
    Aircraft restricted to runways and taxiways
    acft restricted to rwy and twy
    Subject to interruption
    subj intrp
    Limited to
    limited to
    Closed to VFR operations
    clsd vfr ops
    Will take place
    will take place
    Operating but caution advised due to
    opr but caution due
    Other (XX)
    Uniform Abbreviated Phraseology
    Where 4th and 5th letter Code does not cover the situation, use XX and supplement by plain language
    (plain language following the
    NOTAM Code)


    ARFORs - how to read

    By Admin, in Reference Items,

    Area Forecasts For Operations At or Below 10,000 Feet
    The Area Forecast system is designed primarily to meet the needs of pilots of general aviation. There is an emphasis on plain language and brevity in a simple, easy to read format. The system provides for the routine issue of forecasts for designated areas (see map below) and the prompt issue of amendments when prescribed criteria are satisfied.
    More detail of the area forecast boundaries with place locations is contained in Airservices Australia's Planning Chart Australia (PCA).
    There may be variations in commencement of validity between different regions, and between those times when daylight saving is or is not operating. However the following principles apply: the standard validity period is twelve hours but this may vary from state to state. an area forecast covering daylight hours will be available as soon as practicable in the morning. area forecasts are not prepared for those times when air traffic volume is so low as not to justify routine issues. In these cases a route forecast will service any individual flights. area forecasts will generally be available a minimum of one hour before commencement of validity.  
    Message Structure

    Message Identifier
    The forecast is identified as AREA FORECAST unless the forecast is an amendment in which case it will be denoted AMEND AREA FORECAST. In the case of amended area forecasts, all individual sections that are amended will be annotated with AMD preceding the section heading.

    Validity Period
    The validity period is written DDHHMM TO DDHHMM, where DD is the day of the month and HHMM is the time in hours and minutes UTC.

    Area Number
    The relevant forecast area is specified by an area forecast district number. These are given in more detail on the current Airservices Australia's Planning Chart Australia. Note that Areas 24, 87 and 88 are only designated for the purpose of Area QNH. Any flights in these areas can be provided with a route forecast.

    The overview will highlight any conditions which may inhibit safe operations for pilots flying under visual flight rules, and will make reference, where necessary, to any spatial and temporal variations. It will assist the pilot in making the following types of decisions: Are the meteorological conditions Visual Meteorological Conditions (VMC), marginal, Instrument Flight Rules (IFR) or too poor for flying? Is it better to plan for a coastal or inland track? If bad weather is encountered, what is the contingency plan? Return? Change altitude? Change heading? Land immediately?  
    Area forecasts may be divided into spatial, temporal or weather-related subdivisions. Spation subdivisions are given using PCA (Planning Chart Australia) or lat/lon coordinates

    Winds and Temperatures
    Upper level winds are given for 2000 (or 3000 in elevated regions), 5000, 7000, 10 000, 14 000 and 18 500 feet. The expected mean wind direction is given in three figures to the nearest ten degrees True, followed by a solidus (/), followed by the mean wind speed in two figures to the nearest five knots, 290/40. CALM and VRB05 (wind direction variable at 5 knots) are used when appropriate.

    A REMARKS section may be included below the WIND section to provide further information on winds.

    Upper level temperatures are given for 10 000, 14 000 and 18 500 feet. These are given in whole degrees Celsius, following the forecast of the upper wind for the level concerned. e.g. 290/40 PS08, 300/50 ZERO, 360/10 MS10. The abbreviation PS is used for positive temperatures, and MS (minus) is used for negative temperatures.

    The inclusion of cloud is restricted to:
    any CB or TCU. any cloud with a base at or below 5000 feet above the highest terrain in the area covered by the forecast. any cloud layer of more than 4/8 (broken or overcast) amount with base at or below 20 000 feet above MSL. any cloud associated with any forecast precipitation, moderate or severe icing and moderate or severe turbulence.  
    Cloud amount is given using the following abbreviations:
    FEW - Few (1 to 2 oktas) SCT - Scattered (3 to 4 oktas) BKN - Broken (5 to 7 oktas) OVC - Overcast (8 oktas)
    ...except for cumulonimbus and towering cumulus, for which amount is described as:
    ISOL - Isolated OCNL - Occasional (well separated) FRQ - Frequent (little or no separation) EMBD - Embedded (in layers of other cloud)
    Cloud type is given using the following abbreviations:
    CU - Cumulus SC - Stratocumulus CB - Cumulonimbus TCU - Towering cumulus ST - Stratus AS - Altostratus AC - Altocumulus NS - Nimbostratus
    If subdivisions are used and one or more subdivisions have no cloud associated with it, the format used is NIL CLOUD.

    When CU and SC, or AC and AS, occur together at similar heights, they are combined, i.e. CU/SC or AC/AS.

    Cloud base and tops are given in feet above MSL (mean sea level).

    Weather information relating to the layer below 21 000 feet above MSL is given following the word 'WEATHER'. If subdivisions are used and one or more subdivisions have no weather associated with it the format is, WEATHER A: NIL.

    Horizontal visibility is given in metres to the nearest 100 metres up to and including 5000 metres, and in whole kilometres above that value. Forecast visibilities of 50 metres or less are given as 'ZERO'. The forecast value is followed by the units used e.g. '8KM' or '1000M'. Significant variations of visibility are included. If the visibility is forecast to be above 10 kilometres throughout the area, the words 'UNRESTRICTED' or 'GOOD' are used. Vertical variations of horizontal visibility, which might prevent flight under VMC conditions, are significant. For example, information is supplied on the depth of layers affected by drizzle, haze and dust storms, and the levels of haze layers under inversions. Visibility variations with these phenomena is given.

    Freezing Level
    Freezing level is the height, in feet, above MSL of zero degrees Celsius. Reference is made to any variations in height greater than 1000 feet, and to the occurrence of more than one freezing level.

    The icing section gives information on the expected occurrence of moderate or severe icing in cloud (including convective cloud), or precipitation, in the layer below 20 000 feet above MSL.

    The height above MSL of the bottom and top of the layer is given as, for example, MOD IN RA 5000/8000.

    When the layer of icing is expected to extend above 20 000 feet, descriptions such as MOD ABOVE 14000 are used.

    This section provides information on moderate or severe turbulence including turbulence associated with convective cloud.

    The height above MSL of the bottom and top of any layer(s) is given as, for example, MOD IN CLOUD 12000/16000

    When the turbulence is expected to extend to ground level, descriptions such as BELOW 8000 are used.

    When the turbulence is expected to be confined to clouds, descriptions such as MOD IN CLOUD BELOW 8000 are used.

    When the turbulence is expected to extend above 20 000 feet, descriptions such as SEV ABOVE 15000 are used.

    Critical Locations
    These are locations such as gaps in mountain ranges which are frequently used by general aviation aircraft.

    Currently, critical location forecasts are appended to Area Forecasts for Bowral and Mt Victoria (NSW) on AREA 21; Mt Victoria and Murrurundi (NSW) on AREA 20; and Kilmore Gap (Vic) on AREA 30.

    Critical location forecasts are written in a mixture of plain language and TAF format making reference as necessary to cloud, visibility and weather.

    CAVOK is used to indicate visibility greater than 10 KM, cloud ceiling above 5000 FT above ground level and nil significant weather.

    This section will include any relevant information not included elsewhere in the forecast.

    Abbreviations and Codes Used in Area Forecasts
    AC - Altocumulus AC/AS - Altocumulus and Altostratus with bases at the same level AS - Altostratus AMD - Amendment BKN - Broken CAVOK - Cloud and visibility and weather ok. CB - Cumulonimbus CU - Cumulus CU/SC - Cumulus and Stratocumulus with bases at the same level DZ - Drizzle EMBD - Embedded FEW - Few FG - Fog FM - From (only used in Critical Locations section) FRQ - Frequent GR - Hail GS - Small Hail INTER - Intermittent variations (only used in Critical section Locations) ISOL - Isolated MOD - Moderate NS - Nimbostratus OCNL - Occasional OVC - Overcast RA - Rain SC - Stratocumulus SCT - Scattered SEV - Severe SH - Shower SN - Snow ST - Stratus TCU - Towering Cumulus TEMPO - Temporary variations (only used in Critical Locations section) TS - Thunderstorm Z - Code for UTC (universal time)


    METARs - how to read

    By Admin, in Reference Items,

    A METAR is a routine report of meteorological conditions at an aerodrome.

    A SPECI is a special report of meteorological conditions, issued when one or more elements meet specified criteria significant to aviation. SPECI is also used to identify reports of observations recorded ten minutes following an improvement (in visibility, weather or cloud) to above SPECI conditions.

    The location is indicated by either the ICAO (International Civil Aviation Organization) location indicator or another approved abbreviation.

    The day of month and the time of the report is given in UTC (Coordinated Universal Time) using six figures followed by the letter Z. The first two digits are the day of the month; the following 4 digits are the time in hours and minutes, e.g. 291741Z (time of report is 1741 on the 29th of the month UTC).

    The abbreviation AUTO will be included when the report contains only automated observations.

    Surface Wind
    The wind direction is given in degrees true, rounded to the nearest 10 degrees. A variable wind direction is given as VRB.

    The wind speed, given in knots (KT), is the mean value over the sampling period which is normally ten minutes. The maximum wind speed during the sampling period is reported when it exceeds the mean speed by 10 knots or more. It is indicated by the letter G which is followed by the gust value, e.g. a wind direction of 280°, with a mean speed of 20 knots and a maximum gust of 31 knots, is given as 28020G31KT.

    The horizontal visibility is given in metres up to 9000 metres; with 9999 being used to indicate a visibility of 10 kilometres or greater.

    When the visibility is estimated manually (i.e. by an observer), two groups may be reported when the visibility is not the same in different directions. In these cases, the higher visibility will be given first, followed by the minimum visibility and its direction (using one of the eight points of the compass) from the observing station e.g. 9000 2000N.

    When visibility is given by an automated sensor (in fully AUTOmated reports), only one group is reported. The value is followed by the letters NDV (Nil Directional Variation) to indicate that, as there is only one visibility sensor in place, any directional variation in visibility that may exist cannot be detected.

    Weather phenomena are reported using the codes listed in the tables:

    Code Weather Descriptor
    MI - Shallow BC - patches PR - partial DR - drifting BL - blowing SH - showers FZ - freezing TS - thunderstorm
    Code Weather Phenomena
    DZ - drizzle RA - rain GR - hail SN - snow SG - snow grains DU - dust SA - sand SS - sandstorm DS - dust storm GS - small hail/snow pellets PL - ice pellets FG - fog BR - mist FU - smoke HZ - haze PO - dust devil SQ - squall FC - funnel cloud VA - volcanic ash IC - ice crystals PL - ice pellets
    Intensity is indicated for precipitation, blowing dust/sand/snow, dust storm and sandstorm by appending:
    the prefix - for light, e.g. -DZ the prefix + for heavy, e.g. +RA no prefix for moderate, e.g. SHRA  
    One or more codes may be grouped, e.g. +TSGR, -TSRASN

    When precipitation is reported with TS, the intensity indicator refers to the precipitation, e.g. -TSRA = thunderstorm with light rain. Well-developed dust/sand whirls (dust devils) and funnel clouds are reported using the indicator +  
    An observation may provide an indication of weather in the vicinity of the aerodrome, i.e. between 8 and 16KM of the aerodrome reference point. In these cases, the weather code is prefixed with the abbreviation VC (vicinity), e.g. VCTS.

    Cloud information is reported from the lowest to the highest layers in accordance with the following rules:
    1st group: the lowest layer regardless of amount. 2nd group: the next layer covering more than 2 oktas of the sky. 3rd group: the next higher layer covering more than 4 oktas of the sky. Extra groups: for cumulonimbus and/or towering cumulus clouds, whenever observed and not reported in any of the above.  
    Cloud amount is described using the codes in the table:

    Code - Cloud Amount
    SKC - sky clear FEW - few (1 to 2 oktas) SCT - scattered (3 to 4 oktas) BKN - broken (5 to 7 oktas) OVC - overcast (8 oktas) NSC - nil significant cloud NCD* - nil cloud detected * NCD is reported (in fully automated reports only) when a cloud sensor detects nil cloud (a human observer will report SKC when the sky is clear.

    Cloud height is given as a three-figure group in hundreds of feet above the aerodrome elevation, e.g. cloud at 700 feet is shown as 007.

    Cloud type is identified only for cumulonimbus and towering cumulus, e.g. FEW030CB, SCT045TCU.

    When an individual layer is composed of cumulonimbus and towering cumulus with a common base, the cloud is reported as CB only.

    If the sky is obscured, due to, for example, bushfire smoke, human observers will report the vertical visibility (when it can be estimated) in lieu of cloud. It is reported with the prefix VV followed by the vertical visibility in hundreds of feet, e.g. the group VV003 reports an estimated vertical visibility of between 300 and 399 feet (values are rounded down to the next hundred foot increment).

    The abbreviation CAVOK (Cloud and Visibility OK) is used when the following conditions are observed simultaneously:
    Visibility is 10 kilometres or more; No cloud below 5000 feet or below the highest 25NM minimum sector altitude, whichever is the higher, and no cumulonimbus and no towering cumulus; and No weather of significance to aviation, i.e. none of the weather phenomena listed in the weather tables above.  
    Air temperature and dew point values are rounded to the nearest whole degree. Negative values are indicated by M (minus) before the numeral, e.g. 34/M04

    Pressure (QNH)
    The QNH value is rounded down to the next whole hectopascal and is given using four figures prefixed by Q, e.g. 999.9 is given as Q0999

    Supplementary Information
    Supplementary information is used to report:
    Recent Weather - significant weather observed since the last report but not at the time of observation is given after the prefix RE, e.g. RERA. Wind Shear - reports of wind shear experienced on take-off or landing are given after the indicator WS, e.g. WS RWY16.  
    The Remarks section (indicated by RMK) may contain the following:
    Quantitative information on past rainfall is given in millimetres in the form RFRR.R/RRR.R or RFRR.R/RRR.R/RRR.R. The former, e.g. RF00.2/004.2, gives the rainfall recorded in the ten minutes prior to the observation time, followed by the rainfall recorded in the period since 0900 local time. The second format, e.g. RF00.2/003.0/004.2, gives the rainfall recorded in the ten minutes prior to the observation, followed by the rainfall in the sixty minutes prior to the observation, followed by the rainfall recorded in the period since 0900 local time. Information of operational significance not reported in the body of the message, for example: information about significant conditions (such as bushfires and distant thunderstorms) beyond the immediate vicinity of the aerodrome, any BKN or OVC low or middle cloud present at or above 5000 feet when CAVOK has been included in the body of the message, CLD:SKY MAY BE OBSC may be reported in fully automated reports when the ceilometer (cloud sensor) detects nil cloud and the visibility sensor estimates horizontal visibility as being less than 1000 metres  
    Elements of report not available
    Where an element of a report is not available, solidi will be reported in lieu of the missing element, e.g. //// for visibility, // for weather and ////// for cloud.

    SPECI Criteria
    SPECI is used to identify reports of observations when conditions are below specified levels of visibility and cloud base; when certain weather phenomena are present; and when temperature, pressure or wind change by defined amounts (outlined in the table on the right).

    SPECI is also used to identify reports of observations recorded 10 minutes following an improvement in visibility, weather or cloud to METAR conditions.

    Element And Criterion
    Wind Direction - Changes of 30° or more, the mean speed before or after the change being 20KT or more
    Wind Speed - Changes of 10KT or more, the mean speed before or after the change being 30KT or more
    Wind Gust
    Gusts of 10KT or more above a mean speed of 15KT or more Gust exceeds the last reported gust by 10KT or more Visibility - When the horizontal visibility is below the aerodrome’s highest alternate minimum visibility*
    Weather - When any of the following begins, ends or changes in intensity:
    thunderstorm hailstorm mixed snow and rain freezing precipitation drifting snow fog (including shallow fog, fog patches and fog at a distance) dust storm sand storm squall funnel cloud moderate or heavy precipitation Cloud - When there is BKN or OVC cloud below the aerodrome's highest alternate minimum cloud base*
    Temperature - When the temperature changes by 5°C or more since last report
    Pressure - When the QNH changes by 2hPa or more since last report
    Upon receipt of advice of the existence of wind shear The incidence of any other phenomenon likely to be significant *Where no descent procedure is established for an aerodrome, the aerodrome’s alternate ceiling and visibility are 1500 feet and 8 kilometres respectively.

    METAR/SPECI Examples
    METAR YPPH 221130Z 28012G23KT 9000 -SHRA FEW005 BKN050 27/22
    Q0999 RETS RMK RF00.6/003.4 DISTANT TS
    METAR Routine meteorological observation
    YPPH ICAO location indicator for Perth Airport
    221130Z Time of observation is 1130 on the 22nd of the month UTC
    28012G23KT Wind from the west (280 degrees True) at 12 knots; gusting to 23 knots
    9000 Visibility is 9 kilometres.
    -SHRA Present weather is light rain shower
    FEW005 There are 1 to 2 oktas of cloud with base at 500 feet
    BKN050 There are also 5 to 7 oktas of cloud with base at 5000 feet
    27/22 The air temperature is 27°C; the dewpoint temperature is 22°C
    Q0999 The QNH is between 999 and 999.9 hectopascals
    RETS Recent weather was a thunderstorm
    RMK Remarks section follows
    RF00.6/003.4 0.6 mm of rain has fallen in the last 10 minutes; 3.4 mm has fallen since 0900 local time
    DISTANT TS Distant thunderstorm (greater than 16 kilometres from the aerodrome reference point)

    SPECI YSCB 171515Z AUTO 22015G25KT 9000NDV // NCD 13/09 Q1003 RMK
    SPECI Special meteorological observation (for wind gust)
    YSCB ICAO location indicator for Canberra Airport
    171515Z Time of observation is 1515 on the 17th of the month UTC
    AUTO This report is fully automated
    22015G25KT Wind from the southwest (220 degrees True) at 15 knots, gusting to 25 knots
    9000NDV Visibility is 9000 metres; from a single visibility sensor, therefore no directional variation (NDV) in visibility can be detected
    // Present weather is unavailable
    NCD Nil cloud has been detected (by ceilometer)
    13/09 The air temperature is 13°C; the dewpoint temperature is 09°C
    OVC110 There are also 8 oktas of cloud with base at 11 000 feet
    Q1003 The QNH is between 1003 and 1003.9 hectopascals
    RMK Remarks section follows
    RF00.8/003.0 0.8 mm of rain has fallen in the last 10 minutes; 3.0 mm has fallen since 0900 local time


    SIGMETs - how to read

    By Admin, in Reference Items,

    SIGMETs are issued to provide urgent advice to aircraft of actual or expected weather developments or trends that are potentially hazardous.

    SIGMETs are issued to advise of the occurrence or expected occurrence of the following phenomena:

    Code and Description
    OBSC TS - Obscured thunderstorm(s) EMBD TS - Frequent thunderstorm(s) SQL TS - Squall line thunderstorms OBSC TSGR - Obscured thunderstorm(s) with hail EMBD TSGR - Embedded thunderstorm(s) with hail FRQ TSGR - Frequent thunderstorm(s) with hail SQL TSGR - Squall line thunderstorms with hail TC - Tropical cyclone SEV TURB - Severe Turbulence SEV ICE - Severe icing SEV ICE FZRA - Severe icing due to freezing rain SEV MTW - Severe mountain wave HVY DS - Heavy duststorm HVY SS - Heavy sandstorm VA - Volcanic ash RDOACT CLD - Radioactive Cloud
    Pilots in command of aircraft encountering any of the above phenomena not notified by SIGMET advices must report details of the phenomena in an AIREP SPECIAL.

    SIGMET for thunderstorms are only issued when they are:
    obscured (OBSC) by haze or smoke embedded (EMBD) within cloud layers frequent (FRQ), i.e. with little or no separation between clouds and covering more than 75% of the area affected squall line (SQL) thunderstorms along a line of about 100 nautical miles or more in length, with little or no separation between clouds  
    SIGMET for thunderstorms and tropical cyclones do not include reference to icing and turbulence as these are implied as occurring with thunderstorms and tropical cyclones.

    Responsibility for the issuance of SIGMET within Australian FIRs
    SIGMETs for volcanic ash are the responsibility of the Volcanic Ash Advisory Centre, Darwin.

    SIGMETs for tropical cyclones are the responsibility of the Tropical Cyclone Advisory Centres in Perth, Darwin and Brisbane.

    SIGMETs for turbulence and icing above FL185 are the responsibility of the Aviation Weather Centre, Melbourne.

    SIGMET for all other phenomenon are the responsibility of the Meteorological Watch Offices located in Perth, Darwin, Adelaide, Hobart, Melbourne, Sydney, Brisbane and Townsville.

    SIGMET Structure

    Bulletin Identification
    WCAU01 for SIGMET on tropical cyclones WVAU01 for SIGMET on volcanic ash cloud WSAU21 for SIGMET for other phenomena  
    Originating Office (WMO Indicator)
    The World Meteorological Organisation (WMO) location indicators for Australian Meteorological Watch Offices are:

    APRM - Adelaide Regional Forecasting Centre
    APRF - Perth Regional Forecasting Centre
    ABRF - Brisbane Regional Forecasting Centre
    ASRF - Sydney Regional Forecasting Centre
    ADRM - Darwin Regional Forecasting Centre
    AMRF - Melbourne Regional Forecasting Centre
    AMHF - Hobart Regional Forecasting Centre
    ABTL - Townsville Meteorological Office
    AMMC - Melbourne Aviation Weather Centre

    Note: These differ from the ICAO indicators (beginning with Y) used elsewhere in the message.

    Issue Date/Time
    Issue date/time is given in UTC in the form DDHHMM, where DD is day of month, and HHMM is time in hours and minutes.

    Flight Information Region
    Gives the abbreviation for the FIR (YMMM or YBBB) in which the phenomenon is located.

    The message identifier is SIGMET.

    Daily Sequence Number
    The four-character sequence number consists of:
    a two-letter designator to indicate the general location of the event (as given in the two maps below), and a two-digit number, giving the sequence number of SIGMETs issued by the relevant office within the FIR (Brisbane or Melbourne) since 0000 UTC.  
    The tropical cyclone and low-level SIGMET two-letter designators and their associated geographical extent are:

    The high-level (above FL185) icing and turbulence SIGMET two-letter designators and their general associated geographical extent are:

    Validity Period
    The validity period is given in the format DDHHMM/DDHHMM, where DD is the day of the month and HHMM is the time in hours and minutes UTC.

    Tropical cyclone and volcanic ash SIGMETs can have a validity of up to six hours. SIGMETs for other phenomena can be valid for up to four hours.

    Originating Office (ICAO Indicator)
    The International Civil Aviation Organization (ICAO) location indicators for Australian Meteorological Watch Offices are:
    YPRM - Adelaide Regional Forecasting Centre YPRF - Perth Regional Forecasting Centre YBRF - Brisbane Regional Forecasting Centre YSRF - Sydney Regional Forecasting Centre YPDM - Darwin Regional Forecasting Centre YMRF - Melbourne Regional Forecasting Centre YMHF - Hobart Regional Forecasting Centre YBTL - Townsville Meteorological Office YMMC - Melbourne Aviation Weather Centre
    Flight Information Region
    This gives the abbreviation and full name for the FIR in which the phenomenon is located.

    Meteorological Information
    This section includes:
    type of phenomenon observed or forecast location, both horizontal and vertical extents movement or expected movement expected change in intensity SIGMET for tropical cyclone and volcanic ash cloud include a forecast position for the end of the validity period message status  
    Cancel SIGMET
    If during the validity period of a SIGMET, the phenomenon for which the SIGMET is no longer occurring or is no longer expected, the SIGMET is cancelled by issuing a SIGMET with the abbreviation CNL in lieu of meteorological information.

    SIGMET Status
    The status line indicates whether the SIGMET is:
    NEW - the SIGMET is for a new phenomenon. REV - the SIGMET reviews an earlier SIGMET for the phenomenon. CNL - cancels a current SIGMET.  
    The following abbreviations are used in SIGMET:
    Code and Description
    A - Altitude
    ABV - Above
    APRX - Approximately
    BLW - Below
    CNL - Cancel
    DS - Dust storm
    EMBD - Embedded
    FIR - Flight Information Region
    FCST - Forecast
    FL - Flight level
    FRQ - Frequent
    FZRA - Freezing rain
    GR - Hail
    HVY - Heavy
    ICE - Icing
    INTSF - Intensifying
    LOC - Location
    MOV - Moving
    NC - No Change (intensity)
    OBS - Observed
    OBSC - Obscured
    RDOACT CLD - Radioactive cloud
    REV - Review
    SEV - Severe
    SQL - Squall line
    SS - Sand storm
    STNR - Stationary
    STS - Status
    TC - Tropical cyclone
    TS - Thunderstorm
    TURB - Turbulence
    VA - Volcanic ash
    WI - Within (area)
    WKN - Weakening (intensity)
    Z - Universal Time

    SIGMET Examples
    WSAU21 AMMC 180357
    YMMM SIGMET MM01 VALID 180439/180839 YMMC-
    YMMM MELBOURNE FIR SEV TURB FCST WI S3200 E12800 - S3200 E13000 - S4700 E13600 - S4700 E13400 FL260/400 MOV E 25KT NC

    WSAU21 AMMC 180720
    YMMM SIGMET MM02 VALID 180720/180839 YMMC-
    STS:CNL SIGMET MM01 180439/180839

    WCAU01 APRF 180217
    YMMM SIGMET PH01 VALID 180215/180815 YPRF-

    WVAU01 ADRM 200100
    YBBB SIGMET BT04 VALID 200100/200700 YPDM-
    YBBB BRISBANE FIR VA ERUPTION LOC S0416 E15212 VA CLD OBS AT 200100Z A100/180 APRX 120NM BY 40NM S1130 E14530 - S1330 E14900 - S1030 E15030 - S0830 E14700 - S1130 E14430 MOV SW 20KT FCST 0700Z VA CLD APRX S110 E144530 - S1230 E14930 - S1050 E15130 - S0800 E14700 - S1130 E14400 STS:REV SIGMET BT03 191900/200100


    TAFs - how to read

    By Admin, in Reference Items,

    Aerodrome Forecast (TAF)
    A TAF is a coded statement of meteorological conditions expected at an aerodrome and within a radius of five nautical miles of the aerodrome reference point.

    Explanation of TAF Elements
    Identifier and Description
    TAF - Aerodrome Forecast TAF AMD - Amended Aerodrome Forecast TAF COR - Corrected Aerodrome Forecast TAF .. CNL - Cancels Aerodrome Forecast TAF .. NIL - Aerodrome Forecast will not be issued PROV TAF - Provisional Aerodrome Forecast
    The location is given by either an ICAO location indicator or an approved Airservices Australia abbreviation.

    Issue Time
    The issue time of the TAF is expressed in a six-figure group followed by the code letter Z, e.g. 202230Z, which gives an issue time of 2230 on the 20th day of the month UTC.

    The period of validity is given in the format ddhh/ddhh, where dd is day of the month and hh is hour UTC, e.g. 2100/2206, which gives a 30 hour validity period from 0000 the 21st to 0600 on the 22nd UTC. Note that 00 is used to indicate periods of validity beginning at 0000 UTC; and 24 is used to indicate periods of validity ending at 2400 UTC.

    The wind direction is given in degrees True, rounded to the nearest 10 degrees. A variable wind direction is given as VRB (used when the forecasting of a mean wind direction is not possible).
    The wind speed is given in knots (KT).
    The maximum wind gust is included, after the letter G, if it is expected to exceed the mean by 10 knots or more, e.g. a wind direction 280° True, with a mean speed of 20 knots, and a maximum gust of 30 knots, is given as 28020G30KT

    The horizontal visibility is given in metres in increments of 50 metres when visibility is forecast to be less than 800 metres; in increments of 100 metres when forecast to be 800 metres or more but less than 5,000 metres; and in increments of 1,000 metres when forecast to be 5,000 or more but less than 10,000 metres . Visibility is always given in a four figure group: eg 500 metres is given as 0500. Forecast visibilities of 10 kilometres or more are given as 9999. Visibility is not given when CAVOK is forecast.

    Forecast weather is expressed using the following abbreviations:
    MI - shallow BC - patches PR - partial DR - drifting BL - blowing SH - showers FZ - freezing TS - thunderstorm DS - duststorm GS - small hail/snow pellets DZ - drizzle FG - fog RA - rain BR - mist GR - hail FU - smoke SN - snow HZ - haze SG - snow grains PO - dust devil DU - dust SQ - squall SA - sand FC - funnel cloud SS - sandstorm VA - volcanic ash IC - ice crystals PL - ice pellets
    Intensity is indicated for precipitation, blowing dust/sand/snow, duststorms and sandstorms. In these cases, the weather group is prefixed by - for light and + for heavy; moderate intensity has no prefix, e.g. +TSRA means thunderstorm with heavy rain; DZ means moderate drizzle; -RA means light rain.

    After a change group, if the weather ceases to be significant, the weather group is replaced by NSW (nil significant weather) or CAVOK if appropriate.

    Cloud information is given from the lowest to the highest layers in accordance with the following rule:
    1st group: the lowest layer regardless of amount. 2nd group: the next layer covering more than 2 oktas. 3rd group: the next higher layer covering more than 4 oktas. Extra group for cumulonimbus and towering cumulus when forecast but not at any of the layer heights given above.  
    Cloud amount is given using the following abbreviations:
    SKC - sky clear FEW - few (1 to 2 oktas) SCT - scattered (3 to 4 oktas) BKN - broken (5 to 7 oktas) OVC - overcast (8 oktas) NSC - nil significant cloud
    Cloud height is given as a three-figure group in hundreds of feet above the aerodrome, e.g. cloud at 700 feet above the aerodrome is shown as 007.

    Cloud type is identified only for cumulonimbus and towering cumulus, e.g. FEW030CB, SCT040TCU.

    The abbreviation CAVOK (Ceiling and Visibility and weather OK) is used when the following conditions are forecast simultaneously:
    Visibility is 10 kilometres or more, No cloud below 5000 feet or the highest 25 nautical mile minimum sector altitude, whichever is the higher; and no cumulonimbus or towering cumulus at any height, No weather of significance to aviation, i.e. none of the weather listed in the weather table  
    Significant Changes and Variations (FM, BECMG, INTER, TEMPO)
    Significant changes and variations will be included when the changes and variations are expected to satisfy the amendment criteria. It should be noted that these changes relate to improvements as well as deteriorations.

    The term FM is used when one set of prevailing weather conditions is expected to rapidly change to a different set of prevailing weather conditions. The indicator is the beginning of a self-contained forecast, with the new conditions applying until the end period of the forecast or until the commencement time of another FM or BECMG group.

    The term BECMG is used when one set of prevailing weather conditions is expected to gradually change to a different set of prevailing weather conditions. The indicator is the beginning of a self-contained forecast, with the new conditions applying until the end period of the forecast, or until the commencement time of another BECMG or FM group.

    Following any change group (FM or BECMG) there will be information on wind, visibility, weather and cloud; except when CAVOK is given or when fog is forecast.

    Following any change group (FM or BECMG) where there is nil significant weather forecast the abbreviation NSW is used. In some cases where the sky is forecast to be clear after a change group the abbreviation SKC is used.

    The terms TEMPO and INTER are used to indicate significant temporary or intermittent variations from the prevailing conditions previously given in the TAF. TEMPO is used for periods of 30 minutes or more but less than 60 minutes. INTER is used for periods less than 30 minutes.

    Change and variation groups (FM, BECMG, TEMPO, INTER) are not introduced until all information necessary to describe the initial forecast conditions of wind, visibility, weather and cloud have been given.

    Variation groups (TEMPO, INTER) follow at the end of all change groups (FM, BECMG) and before any PROB or TURB.

    The term PROB[%] is used if the estimated probability of occurrence is 30 or 40 percent (probabilities of less than 30% are not given), and is only used with reference to thunderstorms or poor visibility (less than the alternate minimum) resulting from fog, mist, dust, smoke or sand. If the estimated probability of occurrence is greater than or equal to 50 percent, reference is made to the phenomenon in the forecast itself, not by the addition of a PROB. When using PROB with thunderstorms, INTER and TEMPO are also included whenever possible to indicate the probable duration. Where PROB is used without one of these, the likely period of occurrence will be deemed to be one hour or more. For example:
    PROB30 INTER 1205/1211 5000 -TSRA BKN040CB indicates a 30% probability of deteriorations of less than 30 minutes due to thunderstorms with light rain between 0500 and 1100 UTC on the 12th.

    PROB40 TEMPO 1102/1113 3000 TSRA BKN040CB indicates a 40% probability of deteriorations of 30 minutes or more but less than 60 minutes due to thunderstorms with moderate rain between 0200 and 1300 UTC on the 11th.

    PROB30 1005/1014 1000 +TSRA BKN040CB indicates a 30% probability of deteriorations of one hour or more due to thunderstorms with heavy rain between 0500 and 1400 UTC on the 10th.

    RMK (remarks) precedes Turbulence (if forecast) and Temperatures and QNH

    Special reference is made in TAF to hazardous turbulence that may endanger aircraft or adversely affect their safe or economic operation. The TAF contains information on commencement time (FMddhhmm), the expected intensity (moderate [MOD] or severe [SEV]) and the vertical extent (BLW.... FT). TILLddhhmm is used to indicate the cessation of the turbulence when this is expected before the end of the TAF validity.

    Air Temperature
    Temperature, preceded by the letter T, is given in whole degrees celsius using two figures. If the temperature is below zero Celsius, the value is prefixed by the letter M (minus). In Australia, forecasts of air temperature are given at three-hourly intervals, for a maximum of nine hours, from the time of commencement of validity of the forecast. They are given for the times HH, HH+3, HH+6 and HH+9, where HH is the time of the commencement of the TAF validity. They are point forecasts for these times but are valid for, in the case of the first value, ninety minutes after the time point HH; and, for subsequent values, ninety minutes each side of the time point.

    QNH, preceded by the letter Q, is given in whole hectopascals using four figures.

    In Australia, forecasts of QNH are given at three-hourly intervals, for a maximum of nine hours, from the time of commencement of validity of the forecast. They are given for the times HH, HH+3, HH+6 and HH+9, where HH is the time of the commencement of the TAF validity. They are point forecasts for these times but are valid for, in the case of the first value, ninety minutes after the time point HH; and, for subsequent values, ninety minutes each side of the time point.

    TAF Examples
    Example 1
    TAF YMAY 022230Z 0300/0312 35010KT CAVOK
    FM030800 31018KT 9999 SHRA BKN025 OVC100
    INTER 0308/0312 31020G40KT 3000 +TSRA BKN010 SCT040CB
    RMK FM030600 MOD TURB BLW 5000FT
    T 23 24 28 33 Q 1012 1013 1014 1009

    TAF - Aerodrome Forecast
    YMAY - ICAO location indicator for Albury Airport
    022230Z - TAF issued at 2230 on the 2nd day of the month UTC
    0300/0312 - Validity period of TAF is from 0000 to 1200, on the 3rd day of the month UTC
    35010KT - Wind will be from the north (350 degrees True) at 10 knots
    CAVOK - Cloud, visibility and weather ok
    FM030800 - Significant changes to the mean conditions are expected to commence from 0800 on the 3rd UTC, and to persist (at least) until the end of the forecast period

    Note that there will be intermittent variations to these new mean conditions (refer INTER below)
    31018KT - Wind will be from the northwest (310 degrees True) at 18 knots
    9999 - Visibility will be 10 kilometres or more
    SHRA - Weather will be moderate showers of rain
    BKN025 - Cloud will be broken (5 to 7 oktas) with base at 2500 feet above the aerodrome
    OVC100 - There will also be overcast cloud (8 oktas) with base at 10000 feet
    INTER 0308/0312 - There will be intermittent (periods of less than 30 minutes) variations to the previously given mean conditions. Period of INTER is 0800 to 1200 on the 3rd UTC

    31020G40KT - Intermittently the wind will be from the northwest (310 degrees True) at 20 knots gusting to 40 knots
    3000 - Visibility will be 3000 metres
    +TSRA - Weather will be thunderstorms with heavy rain
    BKN010 - Cloud will be broken (5 to 7 oktas) with base at 1000 feet above the aerodrome
    SCT040CB - There will also be 3 to 4 oktas of cumulonimbus cloud with base at 4000 feet
    RMK - Remarks section follows
    FM030600 MOD TURB BLW 5000FT - From 0600 on the 3rd UTC, expect moderate turbulence below 5000 feet
    T 23 24 28 33 - Forecast air temperatures at 00, 03, 06 and 09 UTC are 23, 24, 28 and 33
    Q 1012 1013 1014 1009 - Forecast QNH at 00, 03, 06 and 09 UTC are 1012, 1013, 1014 and 1009.

    Example 2
    TAF COR YMLT 212240Z 2200/2218 31015G28KT 6000 -RA BKN010 OVC100
    TEMPO 2209/2218 2000 +TSRA BKN005 SCT040CB
    T 25 21 18 15 Q 1014 1013 1013 1011

    TAF - Aerodrome Forecast
    COR - This TAF is a correction to the previously issued TAF
    YMLT - ICAO Location Indicator for Launceston Airport
    212240Z - TAF issued at 2240 on the 21st day of the month UTC
    2200/2218 - Validity period of TAF is from 0000 until 1800 on the 22nd of the month UTC
    31015G28KT - Mean wind is expected to be from 310 degrees True at 15 knots with gusts to 28 knots
    6000 - Visibility will be 6000 metres
    -RA - Weather will be light rain
    BKN010 - Cloud will be broken (5 - 7 octas), with base at 1000 feet above the aerodrome
    OVC100 - There will also be overcast cloud, with base at 10,000 feet above the aerodrome
    TEMPO 2209/2218 - There will be temporary variations (periods of 30 to 60 minutes), to the previously given mean conditions, during the period 0900 to 1800 on the 22nd.
    2000 - Visibility will be 2000 metres
    +TSRA - Weather will be thunderstorms with heavy rain showers
    BKN005 - There will be broken (5 to 7 oktas) cloud with base at 800 feet above the aerodrome
    SCT040CB - There will also be scattered (3 to 4 oktas) cumulonmbus cloud with base at 2000 feet above the aerodrome
    RMK - Remarks section follows
    T 25 21 18 15 - Forecast air temperatures at 06, 09, 12 and 15 UTC are 25, 21, 18 and 15
    Q 1014 1013 1013 1011 - Forecast QNH at 06, 09, 12 and 15 UTC are 1014, 1013, 1013 and 1011

    Example 3
    TAF AMD YMML 292330Z 3000/3106 14008KT 9999 NSW SCT030
    FM301100 14003KT 3000 HZ BKN009
    PROB40 3017/3023 0400 FG
    T 14 15 17 14 Q 1016 1014 1013 1014

    TAF - Aerodrome Forecast
    AMD - This TAF amends the previously issued TAF
    YMML - ICAO location indicator for Melbourne Airport
    292230Z - TAF issued at 2230 on the 29th day of the month UTC
    3000/3106 - Validity period of TAF is from 0000 on the 30th until 0600 on the 31st UTC
    14008KT - Mean wind is expected to be from the southeast (150 degrees True) at 8 knots
    9999 - Visibility will be 10 kilometres or more
    NSW - There will be nil significant weather
    SCT030 - Cloud will be scattered (3 to 4 oktas), with base at 3000 feet above the aerodrome
    FM301100 - Significant new mean conditions are expected from 1100 on the 30th UTC;
    14003KT - Mean wind is expected to be from 150 degrees True at 3 knots
    3000 - Visibility will be 3 kilometres
    HZ - Weather will be haze
    BKN009 - Cloud will be broken (5 to 7 oktas), with base at 900 feet above the aerodrome
    PROB40 3017/3023 - There is a 40% probability of conditions being the following during the period 1700 to 2300 on the 30th:
    0400 - Visibility of 400 metres
    FG - Fog
    RMK - Remarks section follows
    T 14 15 17 14 - Forecast air temperatures at 00, 06, 09 and 12 UTC are 14, 15, 17 and 14
    Q 1016 1014 1013 1014 - Forecast QNH at 00, 06, 09 and 12 UTC are 1016, 1014, 1013 and 1014

    1. Insolation and atmospheric temperature
    The Earth's surface and the atmosphere are warmed mainly by insolation — incoming solar electromagnetic radiation. The amount of insolation energy reaching the outer atmosphere is about 1.36 kilowatts per m². About 10% of the radiation is in the near end of the ultraviolet range (0.1 to 0.4 microns [micrometre]), 40% in the visible light range ( 0.4 to 0.7microns), 49% in the short-wave infrared range (0.7 to 3.0 microns ) and 1% is higher energy and X-ray radiation; see 'The electromagnetic wave spectrum' below. The X-rays are blocked at the outer atmosphere, and most of the atmospheric absorption of insolation takes place in the upper stratosphere and the thermosphere. There is little direct insolation warming in the troposphere, which is mostly warmed by contact with the surface and subsequent convective and mechanical mixing; see 'Tropospheric transport of surface heating and cooling' below.

    On a sunny day 75% of insolation may reach the Earth's surface; on an overcast day only 15%. On average, 51% of insolation is absorbed by the surface as thermal energy — 29% as direct radiation and 22% as diffused radiation; i.e. scattered by atmospheric dust, water vapour and air molecules; see 'Light scatter'. About 4% of the radiation reaching the surface is directly reflected, at the same wavelength, from the surface back into space. Typical surface reflectance values, or albedo, are shown below:
    Soils 5–10% Desert 20–40% Forest 5–20% Grass 15–25% Snow, dependent on age 40–90% Water, sun high in sky 2–10% Water, sun low in sky 10–80%  
    In the insolation input diagram shown below it can be seen that about 26% of insolation is directly reflected back into space by the atmosphere but 19% is absorbed within it as thermal energy, with much of the UV radiation being absorbed within the stratospheric ozone layer. Clouds reflect 20% and absorb 3%, and atmospheric gases and particles reflect 6% and absorb 16%.   Altogether some 70% of insolation is absorbed at the Earth's surface and in the upper atmosphere, but eventually all this absorbed radiation is re-radiated back into space as long-wave (3 to 30 microns) infrared. The result of radiation absorption and re-radiation is that the mean atmospheric surface temperature is maintained at 15 °C.

    Terrestrial radiation
    The surface–atmosphere radiation emission diagram below shows that some 6% of input is lost directly to space as long-wave infrared from the surface. Atmospheric O2, N2, and argon cannot absorb the long-wave radiation. Also there is a window in the radiation spectrum between 8.5 and 11 microns where infrared radiation is not absorbed to any great extent by the other gases. About 15% of the received energy is emitted from the surface as long-wave radiation, and absorbed by water vapour and cloud droplets within the troposphere, and by carbon dioxide in the mesosphere. This is actually a net 15%; the total is much greater but the remainder is counter-balanced by downward long-wave emission from the atmosphere.
        Radiation emitted upwards into space, principally nocturnal cooling, is re-radiated from clouds (26%) plus water vapour, O3 and CO2 (38%). The atmosphere then has a net long-wave energy deficit, after total upwards emission (64%) and absorption (15%). This is equivalent to 49% of solar input and a short-wave insolation excess of 19% (16% + 3% absorbed) resulting in a total atmospheric energy deficit equivalent to 30% of insolation.

    Energy balance
    The surface has a radiation surplus of 30% of solar input: 51% short wave absorbed less 21% long wave emitted. This surplus thermal energy is convected to the atmosphere by sensible heat flux (7%) and by latent heat flux (23%). (The 'flux' is a flow of energy). The latent heat flux is greater because the ratio of global water to land surface is about 3:1. Over oceans, possibly 90% of the heat flux from the surface is in the form of latent heat. Conversely over arid land, practically all heat transfer to the atmosphere is in the form of sensible heat.

    Overall the earth—atmosphere radiation/re-radiation system is in balance. But between latitudes 35°N and 35°S more energy is stored than re-radiated, resulting in an energy surplus. But between the 35° latitudes and the poles there is a matching energy deficit. There is also a diurnal and a seasonal variation in the radiation balance. The average daily solar radiation measured at the surface in Australia is 7.5 kW hours/m² in summer and 3.5 kW hours/m² in winter.

    All substances emit electromagnetic radiation in amounts and wavelengths dependent on their temperature. The hotter the substance, the shorter will be the wavelengths at which maximum emission takes place. The sun, at 6000 K, gives maximum emission at about 0.5 microns in the visible light band. The Earth, at 288 K, gives maximum emission at about 9 microns in the long-wave infrared band.

    Tropospheric transport of surface heating and cooling
    The means by which surface heating or cooling is transported to the lower troposphere are: by conduction — air molecules coming into contact with the heated (or cooled) surface are themselves heated (or cooled) and have the same effect on adjacent molecules; thus an air layer only a few centimetres thick becomes less (or more) dense than the air above by convective mixing — occurs when the heated air layer tries to rise and the denser layer above tries to sink. Thus small turbulent eddies build and the heated layer expands from a few centimetres to a layer hundreds, or thousands, of feet deep depending on the intensity of solar heating; see 'Convection'. Convective mixing is more important than mechanical mixing for heating air, and is usually dominant during daylight hours. In hot, dry areas of Australia the convective mixing layer can extend beyond 10 000 feet by mechanical mixing — where wind flow creates frictional turbulence; see 'Frictional turbulence.. Mechanical mixing dominates nocturnally when surface cooling and conduction create a cooler, denser layer above the surface — thus stopping convective mixing. If there is no wind mechanical mixing cannot occur, see 'Fog'. The term (planetary) boundary layer is used to describe the lowest layer of the atmosphere, roughly 1000 to 6000 feet thick, in which the influence of surface friction on air motion is important. It is also referred to as the friction layer or the mixed layer. The boundary layer will equate with the mechanical mixing layer if the air is stable and with the convective mixing layer if the air is unstable. The term surface boundary layer or surface layer is applied to the thin layer immediately adjacent to the surface, and part of the planetary boundary layer. Within this layer the friction effects are more or less constant throughout, rather than decreasing with height, and the effects of daytime heating and night-time cooling are at a maximum. The layer is roughly 50 feet deep, and varies with conditions.

    Heat advection
    Advection is transport of heat, moisture and other air mass properties by horizontal winds. Warm advection brings warm air into a region. Cold advection brings cold air into a region. Moisture advection brings moister air and is usually combined with warm advection. Advection is positive if higher values are being advected towards lower values, and negative if lower values are being advected towards higher; e.g. cold air moving into a warmer region. Advection into a region may vary with height; e.g. warm, moist advection from surface winds while upper winds are advecting cold, dry air.

    2. Electromagnetic wave spectrum
    The electromagnetic spectrum stretches over 60 octaves, the frequency doubling within each octave. For example, the frequencies in octave #18 range from 68.58 MHz to 137.16 MHz — which includes the aviation VHF NAV/COM band. In a vacuum, electromagnetic waves propagate at a speed close to 300 000 km/sec. The frequency can be calculated from the wavelength thus: Frequency in kHz = 300 000/wavelength in metres Frequency in MHz = 300/wavelength in metres or 30 000/ wavelength in centimetres Frequency in GHz = 30/wavelength in centimetres The very high frequency [VHF] band used in civil aviation radio communications lies in the 30 to 300 MHz frequency range — thus the 10 metre to 1 metre wavelength range. The other civil aviation voice communications band is in the high frequency [HF] range; 3 to 30 MHz or 100 to 10 metres.

    The amplitude of the wave is proportional to the energy of vibration. The table below shows the wave length ranges — beginning in nanometres [nm] and progressing through micrometres/microns [µm], millimetres, metres and kilometres — and the associated radiation bands.
    3. Tropospheric global heat transfer
    Precipitation is less than evaporation between 10° and 40° latitudes — the difference being greatest at about 20°. Polewards and equatorwards of these bands precipitation is greater than evaporation. The transfer of atmospheric water vapour, containing latent heat, is polewards at latitudes greater than 20° and equatorwards at lower latitudes. Most of the vertical heat transfer is in the form of latent heat, but possibly 65% of the atmospheric horizontal transfer is in the form of sensible heat following condensation of water vapour. Horizontal latent heat transfer occurs primarily in the lower troposphere.

    The general wind circulation within the troposphere and the water circulation within the oceans transfers heat from the energy surplus zones to the energy deficit zones, thereby maintaining the global heat balance. About 70% is transferred by the atmosphere and 30% by the oceans. The large mid-latitude eddies, and the cyclones and anticyclones in the broad westerly wind belt that flows around the southern hemisphere, play a particularly important part in the transfer of the excess heat energy from low to high latitudes and in the mixing of cold Antarctic air into the mid-latitudes.

    4. Temperature lapse rates in the troposphere
    The temperature lapse rates in the troposphere vary by latitude, climatic zone and season, and vary between less than 0 °C/km (i.e. increasing with height) at the winter poles to more than 8 °C/km over a summer sub-tropical ocean. In the mid-latitudes the temperature reduces with increasing height at varying rates, but averages 6.5 °C/km or about 2 °C per 1000 feet. However, within any tropospheric layer, temperature may actually increase with increasing height. This reversal of the norm is a temperature inversion condition. If the temperature in a layer remains constant with height then an isothermal layer condition exists. At night, particularly under clear skies, the air in the mixed layer cools considerably, but the long-wave radiation from the higher levels is weak and the air there cools just 1 °C or so. Consequently a nocturnal inversion forms over the mixed layer, the depth of which depends on the temperature drop and the amount of mechanical mixing;see 'Fog'.
      Tropospheric average temperature lapse rate profile
    The altitude of the tropopause, and thus the thickness of the troposphere, varies considerably. Typical altitudes are 55 000 feet in the tropics with a temperature of –70 °C and 29 000 feet in polar regions with a temperature of –50 °C. Because of the very low surface temperatures in polar regions and the associated low-level inversion, the temperature lapse profile is markedly different from the mid-latitude norms. In mid-latitudes the height of the troposphere varies seasonally and daily with the passage of high and low pressure systems.

    In the chart above, an exaggerated environmental temperature lapse rate profile has been superimposed to illustrate the temperature layer possibilities — starting with a superadiabatic lapse layer at the surface, a normal lapse rate layer above it then a temperature inversion layer and an isothermal layer.

    5. Adiabatic processes and lapse rates
    An adiabatic process is a thermodynamic process where a change occurs without loss or addition of heat, as opposed to a diabatic process in which heat enters or leaves the system. Examples of the latter are evaporation from the ocean surface, radiation absorption and turbulent mixing.

    An adiabatic temperature change occurs in a vertically displaced parcel of air due to the change in pressure and volume (see the gas equation in 'Gas laws and basic atmospheric forces') occurring during a short time period, with little or no heat exchange with the environment. Upward displacement and consequent expansion causes cooling; downward displacement and subsequent compression causes warming. In the troposphere, the change in temperature associated with the vertical displacement of a parcel of dry (i.e. not saturated) air is very close to 3 °C per 1000 feet, or 9.8 °C / km, of vertical motion; this is known as the dry adiabatic lapse rate [DALR]. As ascending moist air expands and cools in the adiabatic process, the excess water vapour condenses after reaching dewpoint and the latent heat of condensation is released into the parcel of air as sensible heat, thus slowing the pressure-induced cooling process. This condensation process continues while the parcel of air continues to ascend and expand. The process is reversed as an evaporation process in descent and compression. The adiabatic lapse rate for saturated air, the saturated adiabatic lapse rate [SALR], is dependent on the amount of moisture content, which is dependent on temperature and pressure. The chart below shows the SALR at pressures of 500 and 1000 mb (hPa), and temperatures between –40 °C and +40 °C.
    The chart shows that on a warm day (25 °C) the SALR near sea level is about 1.2 °C / 1000 feet. At about 18 000 feet — the 500 hPa level — the rate doubles to about 2.4 °C / 1000 feet.

    The environment lapse rate [ELR] is ascertained by measuring the actual vertical distribution of temperature at that time and place. The ELR may be equal to or differ from the DALR or SALR of a parcel of air moving within that environment. In the atmosphere, parcels of air are stirred up and down by turbulence and eddies that may extend several thousand feet vertically in most wind conditions. These parcels mix and exchange heat with the surrounding air thus distorting the adiabatic processes.

    If the rate of ground heating by solar radiation is rapid, the mixing of heated bubbles of air may be too slow to induce a well-mixed layer with a normal DALR. The ELR, up to 2000–3000 feet agl, may be much greater than the DALR. Such a layer is termed a superadiabatic layer, and will contain strong thermals and downdraughts.

    6. Atmospheric stability
    Atmospheric stability is the air's resistance to any disturbing effect. It can be defined as the ability to resist the narrowing of the spread between air temperature and dewpoint. Stable air cools slowly with height and vertical movement is limited. If a parcel of air, after being lifted, is cooler than the environment, the parcel — being more dense than the surrounding air — will tend to sink back and conditions are stable.

    The temperature of unstable air drops more rapidly with an increase in altitude, i.e. the ELR is steep. If a lifted parcel is warmer, and thus less dense than the surrounding air, the parcel will continue to rise and conditions are unstable. Unstable air, once it has been lifted to the lifting condensation level, keeps rising through free convection. Instability can cause upward or downward motion. When saturated air containing little or no condensation, is made to descend then adiabatic warming causes the air to become unsaturated almost immediately and further descent warms it at the DALR.

    If the ELR lies between the DALR and the SALR, a state of conditional instability exists. Thus, if an unsaturated parcel of air rises from the surface, it will cool at the DALR and so remain cooler than the environment, and conditions are stable. However, if the parcel passes dewpoint during the ascent it will then cool at a slower rate and, on further uplift, become warmer than the environment and so become unstable. High dewpoints are an indication of conditional instability. The figure below demonstrates some ELR states with the consequent stability condition:
        ELR #1 is much greater than the DALR (and the SALR), thus providing absolute instability. This condition is normally found only near the ground in a superadiabatic layer — although a deep superadiabatic layer exists in the hot, dry tropical continental air of northern Australia in summer. ELR # 2 between the DALR and the SALR demonstrates conditional instability. It is stable when the air parcel is unsaturated, i.e. the ELR is less than the DALR; and unstable when it is saturated, i.e. the ELR is greater than the SALR. ELR #3 indicates absolute stability, where the ELR is less than the SALR (and the DALR). Neutral equilibrium would exist if the ELR equals the SALR and the air was saturated, or if the ELR equals the DALR and the air was unsaturated.  
    The following diagram is an example of atmospheric instability and cloud development, and compares environment temperature and that of a rising air parcel with a dewpoint of 11 °C.

    The amount of energy that could be released once surface-based convection is initiated in humid air is measured as convective available potential energy [CAPE]. CAPE is measured in joules per kilogram of dry air. It may be assessed by plotting the vertical profile of balloon radiosonde readings for pressure, temperature and humidity on a tephigram (a special meteorological graph format); and also plotting the temperatures that a rising parcel of air would have in that environment. On the completed tephigram, the area between the plot for environment temperature profile and the plot for the rising parcel temperature profile is directly related to the CAPE, which in turn is directly related to the maximum vertical speed in a cumulonimbus [Cb] updraught.

    One form of aerological diagram is used to determine the stability of the atmosphere — and thus potential thermal activity — by plotting the ELR from radiosonde data and comparing that with the DALR and SALR lines on the diagram. For more information go to the aviation section of the Australian Bureau of Meteorology website and look in the 'Sports Aviation' box for 'How to use the Aerological Diagram'. While there also look in the 'Learning' box for the 'Aviation eHelp' section.

    7. Convergence, divergence and subsidence
    Synoptic scale atmospheric vertical motion is found in cyclones and anticyclones, and is caused mainly by air mass convergence or divergence from horizontal motion. Meteorological convergence indicates retardation in air flow with an increase in air mass in a given volume due to net three-dimensional inflow. Meteorological divergence, or negative convergence, indicates acceleration with a decrease in air mass. Convergence is the contraction and divergence is the spreading of a field of flow.

    If, for example, the front end of moving air mass layer slows down, the air in the rear will catch up — converge — and the air must move vertically to avoid local compression. If the lower boundary of the moving air mass is at surface level, all the vertical movement must be upward. If the moving air mass is just below the tropopause, all the vertical movement will be downward because the tropopause inhibits vertical motion. Conversely, if the front end of a moving air mass layer speeds up, then the flow diverges. If the air mass is at the surface, then downward motion will occur above it to satisfy mass conservation principles. If the divergence is aloft, then upward motion takes place.

    Rising air must diverge before it reaches the tropopause, and sinking air must diverge before it reaches the surface. As the surface pressure is the weight per unit area of the overlaying column of air, and even though divergences in one part of the column are largely balanced by convergences in another, the slight change in mass content of the overriding air changes the pressure at the surface.

    The following diagrams illustrate some examples of convergence and divergence:
    Note: referring to the field of flow diagrams above, the spreading apart (diffluence) and the closing together (confluence) of streamlines alone do not imply existence of divergence or convergence, as there is no change in air mass if there is no cross-isobar flow or vertical flow. (An isobar is a curve along which pressure is constant, and is usually drawn on a constant height surface such as mean sea level.)

    Divergence or convergence may be induced by a change in surface drag; for instance, when an airstream crosses a coastline. An airstream being forced up by a front will also induce convergence. For convergence / divergence in upper-level waves, refer to Rossby waves. Some divergence / convergence effects may cancel each other out; e.g. deceleration associated with diverging streamlines.

    Developing anti-cyclones — 'highs' and high pressure ridges are associated with converging air aloft, and consequent wide-area subsidence with diverging air below. This subsidence usually occurs from 20 000 down to 5000 feet, typically at the rate of 100 – 200 feet per hour. The subsiding air is compressed and warmed adiabatically at the DALR, or an SALR, and there is a net gain of mass within the developing high. Some of the converging air aloft rises and, if sufficiently moist, forms the cirrus cloud often associated with anti-cyclones.

    As the pressure lapse rate is exponential and the DALR is linear the upper section of a block of subsiding air usually sinks for a greater distance (refer to section 2.1 ISA table) and hence warms more than the lower section. If the bottom section also contains layer cloud, the sinking air will only warm at a SALR until the cloud evaporates. Also, when the lower section is nearing the surface, it must diverge rather than descend and thus adiabatic warming stops. With these circumstances it is very common for a subsidence inversion to consolidate at an altitude between 3000 and 6000 feet. The weather associated with large-scale subsidence is almost always dry. However, in winter, persistent low cloud and fog can readily form in the stagnant air due to low thermal activity below the inversion, producing 'anti-cyclonic gloom'. In summer there may be a haze or smoke layer at the inversion level, which reduces horizontal visibility at that level — although the atmosphere above will be bright and clear. Aircraft climbing through the inversion layer will usually experience a wind velocity change.
    Developing cyclones, 'lows' or 'depressions' and low-pressure troughs are associated with diverging air aloft and uplift of air, leading to convergence below. There is a net loss of mass within an intensifying low as the rate of vertical outflow is greater than the horizontal inflow, but if the winds continue to blow into a low for a number of days, exceeding the vertical outflow, the low will fill and disappear. The same does not happen with anti-cyclones, which are much more persistent.
    A trough may move with pressure falling ahead of it and rising behind it, giving a system of pressure tendencies due to the motion but with no overall change in pressure, i.e. no development, no deepening and no increase in convergence.

    8. Momentum, Coriolis effect and vorticity
    Momentum definitions Angular velocityThe rate of change of angular position of the rotating Earth = W = 7.29 x 10–5 radians per second. (One radian = 57.2958°, 2p radians = 360°) or, the rate of angular rotation around a cyclone or anticyclone = w. (A rotor that spins at 1000 rpm has twice the angular velocity of one spinning at 500 rpm). Tangential angular velocityThe tangential angular velocity of a point on the Earth's surface is the product of its radial distance (r) from the Earth's rotational axis and W = Wr. The radial distance from the rotational axis is zero at the poles increasing to maximum at the equator. Angular momentumThe angular momentum of a point on the Earth's surface is the product of the tangential angular velocity and mass (m), and the radial distance from the rotational axis =mWr². If mass is presumed at unity then angular momentum = Wr². Or, angular momentum for a rotating air mass is the product of w and the radius of curvature = wr. Conservation of angular momentumThe principle of conservation of angular momentum states that the total quantity of energy (mass x velocity) of a system of bodies; e.g. Earth–atmosphere, not subject to external action, remains constant. Friction reduces the angular momentum of an air mass rotating faster than the Earth, e.g. a westerly wind, but the 'lost' omentum is imparted to the Earth, thus the angular momentum of the Earth–atmosphere system is conserved.
    Coriolis effect
    Coriolis effect (named after Gaspard de Coriolis, 1792 – 1843) is a consequence of the principle of conservation of angular momentum. The Coriolis or geostrophic force is an apparent or hypothetical force that only acts when air is moving. A particle of air or water at 30° S is rotating west to east with the Earth's surface at a tangential velocity of about 1450 km/hour. If that particle of air starts to move towards the equator, the conservation principle requires that the particle continue to rotate eastward at 1450 km/hour even though the rotational speed of the Earth' surface below it is accelerating as the particle closes with the equator, which is rotating at 1670 km/hour.
      Tangential eastward velocity at the Earth's surface Equator 1670 km/hour 464 metres/sec 15° South 1613 km/hour 448 metres/sec 30° South 1446 km/hour 402 metres/sec 45° South 1181 km/hour 328 metres/sec 60° South 835 km/hour 232 metres/sec 75° South 432 km/hour 120 metres/sec 90° South 0 km/hour 0 metres/sec
    Thus air or water moving towards the equator is deflected westward relative to the Earth's surface. Conversely, air moving from low latitudes, with high rotational speed and momentum, is deflected eastward, i.e. as a westerly wind, when moving to higher latitudes with lower rotational speeds.

    The Coriolis force is directed perpendicular to the Earth's axis, i.e. in a plane parallel to the equatorial plane, so it has maximum effect on horizontal air movement at the poles and no effect on horizontal air movement at the equator. The direction of its action is perpendicular to the particle velocity and to the left in the southern hemisphere, i.e. standing with your back to the wind the Coriolis effect will be deflecting the wind direction to the left (to the right in the northern hemisphere). The rate of turning, or curvature, of a moving particle of air or water is proportional to 2VW sine f, where V is the north/south component of the particle's velocity and f is the latitude. Because sine 90° = 1 and sine 0° = 0, then the Coriolis must be at maximum at the poles and zero at the equator, as expressed above. The Coriolis effect stops turning the moving air only when it has succeeded in turning it at right angles to the force that initiated the movement — a pressure or thermal gradient.

    The Coriolis parameter, f = 2W sine f, is the local component of the Earth's rotation about its axis that contributes to air circulation in the local horizontal plane. It is assumed negative in the southern hemisphere and positive in the northern hemisphere.

    Vorticity or spin is the measure of rotation of a fluid about three-dimensional axes. Vorticity in the horizontal plane, i.e. about the vertical axis, is the prime concern in planetary scale and synoptic scale systems.

    Relative vorticity is taken as horizontal motion, relative to the Earth's surface, about the local vertical axis and is measured as circulation per unit area. It is assumed to be negative if cyclonic and positive if anticyclonic. Relative vorticity z = 2w.

    Absolute vorticity is the relative vorticity plus the Coriolis parameter — which is maximum at the poles and zero at the equator. Relative vorticity is related to horizontal divergence and convergence through the principle of conservation of angular momentum. In the cyclonic movement of air around a low pressure system the fractional decrease in horizontal area due to convergence is matched by a fractional increase in spin, thus conserving the angular momentum. With both increasing vorticity and convergence at lower levels, the vertical extent of the air column is stretched adiabatically and the upper-level divergence lifts to higher levels.

    Conversely, in anticyclonic rotation, the fractional increase in the surface area of the system, due to lower level divergence, is matched by a fractional decrease in spin. With decreasing vorticity and divergence at a lower level, the vertical extent of the air column shrinks adiabatically and the upper level convergence sinks to lower levels.

    The relationship is expressed in the principle of conservation of potential absolute vorticity equation:

    Coriolis parameter + relative vorticity / vertical depth of the air column ( D ) = constant or, f + z / D = constant

    Thus as the Coriolis at a given southern latitude is constant and negative, a reduction in the depth of a column at that latitude requires z to become more positive with consequent anticyclonic rotation. Conversely, an increase in depth requires z to become more negative with consequent cyclonic rotation. The principle accounts for the development of wave patterns in upper air flow. The cyclonic curvature of the isobars can be seen on surface synoptic charts resulting from the easterly / south-easterly trade wind encountering the mountain ranges along the north Queensland coast. The initial reduction in vertical depth as the airstream encounters the barrier, followed by the increase in depth on the western side, induces anticyclonic and cyclonic curvature.

    9. Thermal gradients and the thermal wind concept
    The rate of fall in pressure with height is less in warm air than in cold, and columns of warm air have a greater vertical extent than columns of cold air. Consider two adjacent air columns having the same msl pressure; the isobaric surfaces (surfaces of constant pressure) are at higher levels in the warm air column, which result in a horizontal pressure gradient from the warm to the cold air — this increases with height, i.e. the temperature gradient causes increasing wind to higher levels. The horizontal pressure gradient increases as the horizontal thermal gradient increases — this is known as the thermal wind mechanism.
    The isobaric surface contours vary with height so the geostrophic wind velocity above a given point also varies with height. The wind vector difference between the two levels above the point — the vertical wind shear — is called the thermal wind, i.e. the wind vector component caused by temperature difference rather than pressure difference. On an upper air thickness chart which indicates the heat content of the troposphere, the thermal wind is aligned with the geopotential height lines or with the isotherms on an upper-air constant pressure level chart (isobaric surface chart), and the thicker (warmer) air is to the left looking downwind.

    *Note: a geopotential height line is a curve of constant height, i.e. the height contours relating to an isobaric surface — 850 or 500 hPa for example — usually shown as metres above mean sea level. Thickness charts are similar but show the vertical difference in decametres (i.e. tens of metres, symbol 'dam') between two isobaric surfaces — usually 1000 hPa and 500 hPa. See the national weather and warnings section of the Australian Bureau of Meteorology and view the weather and wave maps.

    An isopleth is the generic name for all isolines or contour lines. An isotherm is a curve connecting points of equal temperature and is usually drawn on a constant pressure surface or a constant height surface.
      The speed of the thermal wind is proportional to the thermal gradient; the closer the contour spacing, the stronger the thermal wind. If the horizontal thermal gradient maintains much the same direction through a deep atmospheric layer — for instance there are no upper level highs or lows, and the gradient is strong with the colder air to the south — then the thermal wind will increase with height, eventually becoming a constant westerly vector. The resultant high-level wind will be high speed and nearly westerly.

    Generally, colder air is to the south so that the thermal wind vector tends westerly. But if the horizontal thermal gradient reverses direction with height, then an easterly thermal wind will occur above that level and the upper-level westerly geostrophic wind speed will decrease with height. Because the direction of the thermal gradient is reversed above the tropopause, the thermal wind reverses to easterly. The horizontal thermal gradient is at maximum just below the tropopause, where the jet stream occurs.

    At latitude 45° S a temperature difference of 1 °C in 100 km will cause an increase in thermal wind of 10 m/sec (or about 20 knots) for every 10 000 feet of altitude — giving jet stream speeds at 30 000 feet, ignoring geostrophic wind. Temperature contrasts between air masses at the polar front will be greatest during winter, giving the strongest jet stream.

    1. Atmospheric structure
    Temperature-related layers
    There are four temperature-related atmospheric regions. The outermost is the thermosphere, within which the temperature rises rapidly with height until about 300 km above Earth's surface. In parts of the thermosphere, the temperature varies diurnally (daily) by 30% or so (200 °C – 300 °C ), due to absorption of ultra-violet solar radiation as thermal energy, without the ability to re-radiate. Depending on the sunspot activity cycle, theoretical molecular temperatures at the 150–300 km level vary between 200 °C and 1700 °C but due to the rarified atmosphere there is little sensible heat capacity, i.e. a normal thermometer would sense a temperature less than 0 °C. The absorbed heat is conducted downward below 100 km where the atmosphere can re-radiate at night.

    'Space' is said to start at 100 km altitude, which would mark the thermosphere as the beginning of space.
    Temperature decreases rapidly with height in the mesosphere (from the Greek 'mesos' — middle); the minimum of about –90 °C is reached at the mesopause located at about 80 km where atmospheric pressure is about 0.01 hPa. Carbon dioxide in the mesosphere is an important absorber of terrestrial infra-red radiation. A group of wind systems is centred within the mesosphere, just above the stratopause, extending into the stratosphere and, to some extent, the thermosphere.

    Most of the atmosphere's ozone [O3] is contained within the stratosphere (from the Latin 'stratum' — layered); the O3 is produced between the 30 and 60 km levels by reaction between atomic oxygen [O] and molecular oxygen [O2]. Atmospheric circulation transports ozone down to the 25 km level where maximum density occurs — this is the ozone layer. The ozone content tends to concentrate at lower levels in the higher latitudes during the winter months and is transported to lower latitudes during spring. Ozone blocks about 90% of the sun's UV radiation — roughly all radiation between 0.25 and 0.35 micrometres. That UV energy absorption results in the temperature in the upper half of the stratosphere increasing until the stratopause. The temperature in the lower half of the stratosphere tends to remain constant or increase slightly with height, thus the layer is usually very stable. Some vertical mixing occurs and there is east-west and west-east circulation, but once gases or particles enter the stratosphere they tend to stay in it for long periods.

    The troposphere (from the Greek 'tropos' — [over]turning) — its thickness varying from about 8 km at the poles to 28 km at the equator, and varying daily and seasonally — contains virtually all the atmospheric water and more than 90% of the air mass. Condensation of water vapour, forming clouds, occurs almost exclusively in the lowest 8 km where the water vapour comprises up to 3% or 4% of the atmosphere by volume. The troposphere is heated by terrestrial long-wave radiation plus turbulent mixing of latent and sensible heat. Vertical air movement can be pronounced and temperature decreases linearly with height until the tropopause. The low temperature at the tropopause (–40 °C to –50 °C in the mid-latitudes) allows very little water vapour to pass above it; refer atmospheric moisture below.

    Composition-related layers
    The troposphere, stratosphere and mesosphere constitute the homosphere (from the Greek 'homos' — same) in which the composition of the atmosphere is more or less uniform throughout. The composition is primarily nitrogen (78%), oxygen (21%) and argon (<1%), plus other trace gases and particles; the two major non-permanent gases ozone (O3) and water vapour (H2O), plus carbon dioxide (CO2), are particularly important as radiation absorbers because of their triatomic structure. The average atmospheric relative molecular mass throughout the homosphere is about 29 atomic mass units (amu).

    The relative molecular weight of the main atmospheric components is:
    Relative weight of atmospheric gases
    (atomic mass units) Atomic forms Diatomic forms Triatomic forms H He C O H2 N2 O2 H2O CO2 O3 1 4 12 16 2 28 32 18 44 48
    The composition changes above the mesopause. The atmospheric gases tend to separate into layers according to the relative molecular weight of the individual components, thus the average relative molecular mass decreases with height. This second composition layer, which extends to inner space, is the heterosphere (from the Greek 'heteros' — other).There is little or no nitrogen (N2) above 150 km, atomic oxygen (O) dominates between 300 and 1000 km, helium (He) between 1000 and 2000 km, and hydrogen (H) above that.

    Radiation-related layers
    In the photochemical ionosphere (which is mostly contained within the thermosphere but also partly extends into the neighbouring mesosphere), cosmic radiation of high-energy sub-atomic particles and the absorption of much of the solar ultraviolet radiation separates negative electrons from oxygen and nitrogen molecules. The ions and free electrons move rapidly under the influence of electrical forces — the ionospheric wind — and the ionosphere is highly conductive; see the global circuit. Oxygen is chemically active when affected by shortwave ultraviolet radiation and molecular (diatomic) oxygen, O2 , dissociates into atomic (monatomic) oxygen. Above 150 km the molecular nitrogen separates out owing to its higher mass, and the atmosphere is predominantly atomic oxygen. The excitation of oxygen and nitrogen atoms by collision with charged particles (separated hydrogen electrons and protons) from outburst emissions of solar wind produces the aurorae in the ionosphere.

    Several ionisation layers are formed in the ionosphere that affect radio communications: The F2 or Appleton layer is at about 400 km by day, descending to 200 km at night. Ionisation varies from 106 free electrons/cc during the day to 105 at night. The layer refracts LF, MF and HF radio transmission waves. But transmissions in the VHF, UHF and higher radio frequencies — which are those used by sport and recreational aviation — are not significantly affected.
      The F1 layer is at about 200 km. Nitrogen is ionised by short-length UV radiation in the F layers.
      The E or Heaviside-Kennelly layer is at 90–150 km. It has 105 free electrons/cc by day, but disappears at night. The E layer partially reflects LF, MF, HF and sometimes VHF signals back to earth. At night, it is replaced by the F2 layer at 200 km. The longest X-rays ionise oxygen and nitrogen.
      The D layer, where N2O is ionised by medium length UV, exists only during daylight at 50–90 km. It reflects LF and VLF waves, absorbs MF and attenuates HF. Solar outbursts (sunspots, flares) radiate X-rays in abnormal quantity and ionise the E and D layers strongly, lowering their altitude and adversely affecting HF communications during the day.
      The changes in the ionisation layers affect the sky waves of older navigation aids such as non-directional beacons which operate in the LF band. Errors in directional indications will increase, particularly during the morning and evening twilight periods.  
    The energy-absorbing region from the tropopause to the D layer, i.e. the stratosphere and the mesosphere, is the ozonosphere. Ultraviolet radiation dissociates the water vapour that reaches the stratosphere and higher regions into hydrogen and oxygen atoms.

    When such atoms reach the exosphere (from the Greek 'exo' — outside) — above the thermopause at about 500 km and extending out for an indeterminate distance, where the lighter components predominate — some atoms, particularly helium and hydrogen, will reach escaping velocity. The temperature within the exosphere remains roughly constant with height, although it varies daily and seasonally.

    The magnetosphere limits the Earth's geomagnetic field. Within it are the Van Allen belts of high-energy solar wind and cosmic radiation particles trapped by the magnetic field. The outer, mainly electron, belt is centred about 18 000 km above the equator. The inner, more energetic and mainly proton, belt is centred at 3000 km. Changes within the magnetosphere may influence weather.

    2. Gas laws and basic atmospheric forces
    Gas laws
    The density (the mass of a unit of volume) of dry air is about 1.2 kg/m³ at mean sea level [msl] and decreases with altitude. The random molecular activity within a parcel of air exerts a force in all directions and is measured in terms of pressure energy per unit volume, or static pressure. This activity, i.e. the internal kinetic energy, is proportional to the absolute temperature. (Absolute temperature is expressed in kelvin units [K]. One K equals one degree Celsius and zero degrees in the Celsius scale is equivalent to 273 K, so 20 °C equals an absolute temperature of 293 K.) There are several gas laws and equations that relate temperature, pressure, density and volume of a gas.

    Boyle's law: At a constant temperature the volume [V] of a given mass of gas is inversely proportional to the static pressure [P] upon the gas; i.e. P × V = constant.

    The pressure law: At a constant volume the static pressure is directly proportional to temperature [T] in kelvin units.

    Charles' law: At a constant pressure gases expand by about 1/273 of their volume, at 273 K, for each one K rise in temperature; i.e. the volume of a given mass of gas at constant pressure is directly proportional to the absolute temperature. If an amount of heat is taken up by a gas some of the heat is converted into internal energy and the balance is used in the work done in pushing back the environment as the gas expands.

    The gas equation: For one mole* of gas, the preceding laws are combined in the gas equation PV = RT where R = the universal gas constant = 8.314 joules per Kelvin per mole. The specific gas constant for dry air (i.e. no water vapour present) is 2.87 when P is expressed in hectopascals [hPa]. Ordinary gases do not behave exactly in accordance with the gas laws because of molecular attraction and repulsion. The gas equation approximates the behaviour of a parcel of air when temperature or pressure, or both, are altered; e.g. if temperature rises and pressure is constant, then volume must increase — consequently the density of the air decreases and the parcel becomes more buoyant. Conversely, if temperature falls and pressure is constant then volume must decrease, the air becomes denser and the parcel less buoyant. Warmed air is comparatively light and cooled air is comparatively heavy. (In meteorological terms a parcel is a mass of air small enough that the whole mass moves or behaves as a single object.)

    *Note: a mole is the basic SI unit of amount of substance. One mole of any substance contains 6 x 10²³ molecules, the latter being the number of molecules in 12 grams of carbon-12.)

    The equation of state: P = RrT / M where r = density and M = molecular weight. But for meteorological purposes M is ignored and the equation used is P = 2.87rT. For example, if density remains constant and the temperature increases (decreases), then static pressure increases (decreases) or conversely, if density remains constant and the pressure increases (decreases) then temperature increases (decreases). Or, if pressure remains constant then an increase in temperature causes a decrease in density, and vice versa. For our purposes pressure is expressed in hectopascals, density in kilograms per cubic metre and temperature in kelvins.

    Dalton's law: The total pressure of a mixture of gases or vapours is equal to the sum of the partial pressures of its components. The partial pressure is the pressure that each component would exert if it existed alone and occupied the same volume as the whole. As powered recreational aircraft operate at altitudes below 10 000 feet, the component that we have most interest in is the partial pressure of water vapour because that affects the formation of mist, fog and cloud, but above 8000 feet or so the decreasing oxygen partial pressure may start to affect pilot performance — see the 'Physiological effects of altitude'.

    Basic atmospheric forces
    The basic forces acting in the atmosphere are:
    Gravity, which acts vertically towards the centre of the Earth
      The vertical pressure gradient force, which acts vertically upwards; and the horizontal pressure gradient force, which acts horizontally. Expanded in the following section 1.3.
      Coriolis effect, which induces turning or curvature in horizontal air flow; refer to Coriolis force.
      Friction, which acts to retard horizontal air flow particularly at the surface; refer to these sections; 'Frictional turbulence', 'Velocity change between surface wind and gradient wind and 'Boundary layer turbulence'.
    3. Atmospheric pressure and buoyancy
    The pressure gradient
    Atmospheric pressure reflects the average density and thus the weight of the column of air above a given level. Thus the pressure at a point on the Earth's surface must be greater than the pressure at any height above it. An increase in surface pressure denotes an increase in mass, not thickness, of the column of air above the surface point. Similarly a decrease in surface pressure denotes a decrease in the mass. The gradient is the difference in pressure vertically and horizontally.

    The air throughout the column is compressed by the weight of the atmosphere above it. Thus the density of a column of air is greatest at the surface and decreases exponentially with altitude as shown in the following graph, which is a plot of the rate of decrease in density with increase in altitude. The plot is for dry air at mid-latitudes. ( Mid-latitudes are usually accepted to be the areas between the 30° and 60° parallels, while low latitudes lie between the equator and 30°, and high latitudes between 60° and the poles.) The atmosphere at about 22 000 feet has only 50% of the sea level density. Density decreases by about 3% per 1000 feet between sea level and 18 500 feet, and thereafter the density lapse rate slows.
    The dry air density gradient in mid-latitudes. See the 'International Standard Atmosphere'.
    As the pressure decreases with height so, in any parcel of air, the downwards pressure over the top of the parcel must be less than the upwards pressure under the bottom. Thus within the parcel there is a vertical component of the pressure gradient force acting upward. Generally this force is balanced by the gravitational force, so the net sum of forces is zero and the parcel floats in equilibrium. This balance of forces is called the hydrostatic balance. When the two forces do not quite balance, the difference is the buoyancy force. This is the upward or downward force exerted on a parcel of air arising from the density difference between the parcel and the surrounding air. A visible application of this principle is readily apparent in the hot-air balloons and airships of sport and recreational aviation.

    Atmospheric pressure also varies horizontally due to air mass changes associated with the regional thickness of the atmospheric layer. The resultant horizontal pressure gradient force, not being balanced by gravity, moves air (as wind) from regions of higher pressure towards regions of lower pressure. But the movement is modified by the Coriolis effect. The horizontal force is very small, being about 1/15 000 of the vertical component.

    (Advection is the term used for the transport of momentum, heat, moisture, vorticity or other atmospheric properties, by the horizontal movement of air: see 'Heat advection')

    The following graph plots the average mid-latitude vertical pressure gradient and shows how the overall vertical decrease in pressure — the pressure lapse rate — slows exponentially as the air becomes less dense with height. In a denser or colder air mass the pressure reduces at a faster rate. Conversely, in less dense, or warmer, air the pressure reduces at a slower rate. (The hydrostatic equation states that the vertical change in pressure between two levels in any column of air is equal to the weight, per unit area, of the air in the column.) If two air columns have the same pressure change from top to bottom, the denser column will be shorter. Conversely, if the two columns have the same height, the denser column will have a larger change in pressure from top to bottom.
    In the ICAO standard atmosphere the rate of altitude change for each 1 hPa (or millibar [mb]) change in pressure is approximately:
    0 to 5000 feet: 30 feet/hPa or 34 hPa per 1000 feet 5000 to 10 000 feet: 34 feet/hPa or 29 hPa per 1000 feet 10 000 to 20 000 feet: 43 feet/hPa or 23 hPa per 1000 feet 20 000 to 40 000 feet: 72 feet/hPa or 14 hPa per 1000 feet
    The change in altitude for one hectopascal change in pressure can be calculated roughly from the absolute temperature and the pressure at the level using the equation: altitude change = 96T/P feet.

    Atmospheric oxygen and partial pressure
    In the homosphere each gas, including water vapour, exerts a partial pressure, which is the product of the total atmospheric pressure and the concentration of the gas. As oxygen represents about 21% of the composite gases, the partial pressure of oxygen is about 21% of the atmospheric pressure at any altitude within the homosphere.

    Interpolating from the pressure gradient graph above, oxygen partial pressure at selected altitudes is shown below. The decreasing partial pressure of oxygen as an aircraft climbs past 10 000–12 000 feet has critical effects on aircrew; the maximum exposure time — for a fit person — without inspiring supplemental oxygen, is shown in the right-hand column. Perception gradually decreases within the exposure times and exposure beyond these times leads to unconsciousness.
      Altitude (ft) O2 pressure (hPa) Maximum exposure time Sea level 210 — 7000 165 — 10 000 150 — 15 000 120 30+ minutes 18 000 105 20–30 minutes 25 000 80 3–5 minutes 30 000 65 1–3 minutes 35 000 50 30–60 seconds 40 000 30 10–20 seconds
    For further information see 'Physiological effects of altitude' in the Flight Theory Guide.

    4. Atmospheric moisture
    Water vapour partial pressure, saturation and density
    Gas molecules normally exert attractive forces on each other, except when in very close proximity where the interaction is repulsive. If a gas or vapour is cooled so that molecular movements become relatively sluggish, the attractive forces draw the molecules close together to form a liquid. This process is condensation and water vapour is the only atmospheric gas that displays this property in nature.

    A moist atmosphere that includes water vapour is slightly less dense than a dry atmosphere at the same temperature and pressure; because the vapour displaces a corresponding amount of the other gases per unit volume and the molecular weight ratio of water vapour to dry air is 0.62:1*. Thus a parcel of moister air is slightly more buoyant than surrounding drier air.

    *Note: referring to the 'Relative weight of atmospheric gases' table above, the mass of a molecule of H2O is 18 atomic mass units (amu) while that of the oxygen (O2) and nitrogen (N2) diatomic molecules, that make up 21% and 78% of the atmospheric gases, is 32 amu and 28 amu respectively. So the mass of a dry air molecule averages about 29 amu and water vapour mass (18 amu) is 62% of that. As the water vapour molecule occupies about the same space as the dry air molecules it displaces, so air density (mass per unit volume) decreases a little as the humidity of the air increases, and this should be considered when calculating density altitude. Air doesn't 'hold' water, rather the water vapour molecules 'displace' air molecules.

    Vapour partial pressure is a measure of the amount of water vapour included in a parcel of air and increases as the amount of vapour increases. Moist air — including the maximum amount of water vapour that can be included, without condensation occurring at the prevailing temperature — is saturated; i.e. the water vapour pressure is equal to its maximum under that particular condition, and is in equilibrium with a surface of liquid water (e.g. an ocean surface or a water droplet, a water-filled sponge or seasoned wood) at the same temperature. When in equilibrium the same number of water molecules are condensed from the air back into the moist surface as are evaporated from the surface into the air. Water vapour and adjacent moist bodies are always striving for equilibrium, and the equilibrium state is achieved at the saturation vapour partial pressure, the level of which is a function of temperature.

    If saturated air is cooled it becomes supersaturated and the excess water vapour immediately condenses onto aerosols (microscopic particles — larger than molecules — of dust, smoke, pollution products and salt small enough to remain suspended in the atmosphere) and forms the minute water droplets of mist or cloud; see 'Cloud formation'. The overwhelming majority of aerosols in the upper atmosphere are built up in the cosmic radiation processes and are smaller than the wavelength of light, whereas the larger particles are found near the surface. Those condensation nuclei that have a very high affinity with water — such as salt — are termed hygroscopic particles — substances that absorb water vapour from the air. Such nuclei, which originate mainly from sea spray or dust containing salt, help in the initiation of condensation; as it will occur on them well before air is saturated — in the case of sodium chloride it is at 78% relative humidity. If the atmosphere were completely without aerosols, no condensation would occur until extreme supersaturation existed. If cloud droplets or ice crystals already exist, condensation will take place upon them.

    The maximum amount of vapour that can be present depends on temperature. A warm atmosphere has greater capacity for water vapour than a cold one; e.g. one kg of air at 35 °C can include 35 grams of vapour whereas one kg of air at –15 °C can include only one gram. Generally the atmosphere at a tropical ocean surface is 60 times moister than that at 15 000 feet over polar regions.

    The graph below plots the saturation vapour partial pressure, over a liquid water surface, for air temperatures between –20 °C and 45 °C.
    Saturation vapour partial pressure and dew point temperature
    The dew point is the temperature to which moist air must be cooled, at a given pressure and water vapour content, for it to reach saturation. Condensation occurs when the temperature falls below dew point; e.g. from the graph above it can be seen that an air parcel at 25 °C and 20 hPa vapour partial pressure would reach its dew point on the curve if it were cooled below 17 °C. Very dry air can have a dew point well below 0 °C. At ground level if dew point is below freezing, a light, crystalline hoar frost forms; but if dew forms before ground temperature subsequently falls below freezing then frozen, or white dew, results.

    Note: the spread between surface temperature and dew point temperature is an indication of relative humidity and the convection condensation level; e.g. the cloud base may be 1000 feet agl for each 2 °C of spread but inversions, turbulence, etc. will modify this. If the spread is less than 1.5 °C then ceiling and visibility may go below VFR minima. But at 2 °C or greater, CAV may be marginal to OK. Cloud scraps seen to be forming near the surface are a forewarning of visibility problems at low levels.

    The frost point is the point to which moist air must be cooled for it to reach saturation over an ice surface (e.g. airborne ice crystals). Further cooling induces direct deposition of ice onto solid surfaces, including ice surfaces.

    The saturation partial pressure at temperatures below freezing differs for water and ice surfaces. Thus it is possible that air is supersaturated, relative to ice crystals in clouds, but unsaturated for supercooled liquid cloud droplets. See 'Snow'.
      Saturation vapour pressure/temperature over ice/water Ambient temperature °C: 0 –10 –20 –30 –40 –60 SVP over water (hPa): 6.1 2.9 1.3 0.5 0.2 - SVP over ice (hPa): 6.1 2.6 1.0 0.4 0.1 0.01
    The very low saturation partial pressures between –40 °C and –60 °C, corresponding to temperatures at the tropopause, indicate that only minute amounts of water vapour can pass through the tropopause into the stratosphere.

    Quantifying atmospheric humidity
    Specific humidity is the mass of water vapour per unit mass of the moist air in grams per kg.

    Humidity mixing ratio is the ratio of the mass of water vapour to the mass of dry air expressed as grams of vapour per kilogram of dry air. It is normally very close to specific humidity except in very humid air.

    Dry bulb temperature is the ambient or outside air temperature (OAT)— the heat content of the air.

    Wet bulb temperature is the lowest temperature to which the ambient air (flowing around a moistened thermometer bulb) can be cooled by the evaporation of water; see 'Evaporation and latent heat'. The greater the humidity, the lesser the evaporation — which ceases at 100% relative humidity, when the wet bulb temperature will equal the normal dry bulb temperature. If air at 100% relative humidity is cooled, dew point is reached and condensation starts to occur. The dry and wet bulb thermometers comprise a hygrometer; a hygroscope just indicates change in humidity.

    Relative humidity [RH] is the ratio of the amount of water vapour in a parcel of air to the amount that would be present at saturation point, at the same temperature, and is usually expressed as a percentage; i.e. actual density / saturation density x 100. RH can also be calculated as vapour partial pressure / saturation vapour pressure x 100. Thus from the preceding graph, a parcel of air at 25 °C and 20 hPa partial pressure would reach the saturation curve at 32 hPa partial pressure; therefore the existing relative humidity is 20 / 32 x 100 = 62%. The humidity level published in daily weather reports is the relative humidity.

    Note that if the temperature of an air parcel changes, then the RH changes. For example, if the amount of water vapour present remains constant, RH decreases when air temperature increases and vice versa. During the evening the temperature falls and the RH increases — if 100% RH is exceeded condensation (evening mist) appears. RH does not indicate the actual amount of vapour present, but in hot weather an increase in RH makes people feel hotter because of the decreased evaporation of perspiration; we rely on evaporative cooling for body temperature control in hot weather.

    The table below provides relative humidity if the dry bulb and wet bulb temperatures are known. Airfield altitude has a very slight effect in Australia as there are few airfields/airstrips with an elevation exceeding 4500 feet.
    Relative humidity table   Dry bulb Difference between dry bulb and wet-bulb temperatures
    Relative humidity                   °C -1° -2° -3° -4° -5° -6° -7° -8° -9° -10° Rule of
    thumb value 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% 20° 91% 83% 75% 67% 59% 52% 45% 38% 31% 26% 25° 92% 85% 77% 71% 64% 57% 51% 45% 39% 33% 30° 93% 86% 79% 73% 67% 61% 55% 50% 45% 40% 35° 93% 87% 81% 75% 69% 64% 59% 54% 49% 44% 40° 94% 88% 82% 77% 71% 66% 62% 57% 52% 48% 45° 94% 89% 83% 78% 73% 69% 64% 60% 55% 51%
    5. Evaporation and latent heat
    The amount of moisture contained in the atmosphere at any one time is about 13 000 km³ of water and is equivalent to a world-wide precipitation of 25 mm. As the annual world-wide precipitation is about 850 mm, it follows that the atmospheric moisture is being replenished by evaporation about 35 times per year, or every 10 days or so. About 85% of the moisture evaporates from the oceans, the balance evaporating from fresh-water sources, moist earth and transpiration from plants. Vaporisation is the process of conversion of a substance from the liquid into the vapour state. Fusion is the conversion from solid to liquid state; e.g. snow crystals to rain.
    Molecules of water in a condensed state are held to one another by strong forces of attraction, which are balanced by equally strong repulsive forces. Tending to overcome the potential energy of attraction is the escaping tendency of molecules, arising from their kinetic energy. The kinetic energy, and thus the escaping tendency, is a function of absolute temperature. At each temperature a certain fraction of the molecules possesses enough kinetic energy to overcome the forces of attraction of the surrounding molecules and to escape from the surface of the water as vapour — whether that surface is an ocean or a cloud droplet. As the molecules that possess excessive kinetic energy (heat) evaporate from the liquid, the average kinetic energy of the remaining molecules decreases and the temperature drops. The heat energy carried away with the water vapour, about 2500 joules per gram of vapour, is the latent heat of vaporisation (this is the principle of the wet-bulb thermometer). Conversely, when water vapour condenses back into the liquid state, the latent heat of condensation is released into the surrounding air as sensible heat (that increases the air temperature) and has a significant effect on the saturated adiabatic lapse rate. Sensible heat is a function of air temperature while latent heat is a function of H2O changing its state, e.g. from liquid to gas.

    Ice melts at 0 °C and requires 330 joules per gram — the latent heat of fusion. If ice is converted directly to water vapour, at the same temperature, it takes about 2800 joules per gram — the latent heat of sublimation. Sublimation is also the process where water vapour is converted directly to ice; e.g. hoar frost forming on a chilled windscreen during take-off or carburettor icing.

    6. Atmospheric and solid Earth tides
    In the low latitudes a semi-diurnal pressure variation is quite noticeable. Atmospheric pressure peaks at about 1000 hours and 2200 hours local solar time, with minima at 1600 and 0400. The semi-diurnal pressure variation at Cairns in tropical Australia is about 2 hPa either side of the mean; i.e the pressure might be 1015 hPa at 0400, 1019 hPa at 1000, 1015 hPa at 1600 and 1019 hPa at 2200. Meteorologists adjust the daily pressure observations to remove the tide effect.

    The atmospheric tide is associated with lunar and solar gravitation, solar heating, and resonance. The tide is not apparent in latitudes greater than 50°–60°. The atmospheric tide is an internal gravity wave with a 12-hour frequency.

    The semi-diurnal pressure variation is similar to the semi-diurnal gravity variations at the Earth's solid surface, the solid earth being subject to tides — the solid Earth tide — caused by lunar/solar gravitation. A point on the Earth's surface might move up and down by as much as 50 cm, with maximum gravitation occurring every 12 hours or so. The solid tide movement is something to be considered in future aircraft GNSS precision approach and landing systems.

    Sport and recreational aviation is no longer purely the realm of dedicated minimum aircraft afficionados but has matured into an authoritative industry, well endowed with professional aviation business people and a number of recreational aeroplane manufacturers in regional Australia. These manufacturers currently produce most of the Australian-made factory fly-away aeroplanes — civil or military. In addition they, and other producers, supply aircraft kits for the many home-building enthusiasts — both in Australia and overseas. At the same time there are many RA-Aus members who are exercising their skills in designing and building their own recreational aircraft, or constructing them from commercially available plans. Leisure aviation also fostered the growth of the major existing Australian manufacturer of certificated aero-engines — Jabiru Aircraft.

    How the current status came about is best illustrated by reviewing the history of minimum aircraft and power-driven sport and recreational aviation in Australia.

    Please note: the following history is an ongoing compilation being put together from many sources; it was started in 2002, and from 2004 an annual survey was appended.

    I believe it is reasonably accurate but corrections — and additions — are sought and welcomed. The history generally covers only trikes and power-driven fixed-wing aeroplanes — with some mention of powered parachutes — but the 'power-assisted' sailplanes, motorised hang gliders and motorised paragliders are not included. The trikes administered by the Hang Gliding Federation of Australia and the gyroplanes of the Australian Sports Rotorcraft Association have little mention, solely due to the author's lack of knowledge; but I would be very happy to include more.

    1. The 'flexwing' hang glider and weight-shift control trike enter the aviation scene
    1891–1896 Otto Lilienthal designed and flew several weight-shift controlled hang gliders in Germany. He made perhaps 2000 flights between 1891 and his accidental death in 1896. He can properly be regarded as the father of hang-gliding and weight-shift control — which became so popular 70 years after his death.

    1961 Practically all aircraft wing development since 1910 was associated with rigid wings but experiments by an American aeronautical engineer, Francis Rogallo (1912–2009), with a delta-shaped flexible wing — the Rogallo wing, which was patented in 1948 — culminated in NASA's Paraglider Research Vehicle project evaluating the flexible wing concept for suitability as a recovery vehicle for the Gemini spacecraft; among other uses in vehicle recovery. Several low-speed three-axis controlled light aircraft were built as part of the project — which was finally dropped in favour of parachute recovery. But the technology acquired helped kick-start the contemporary hang glider industry, and many foot-launched hang glider designs were developed around the world.

    1963 An Australian — John Dickenson — had been working on wing designs for a tail-less kite to be towed behind the speed boats of the Grafton Water Ski Club. When shown a photograph of a Rogallo wing he decided to adapt the concept to his 'ski-wing' project. John designed a simple, flexible wing consisting of a pair of single-surface, plastic sheeting (as used for protecting banana bunches grown in the area) sails each with a leading-edge spar, joined at a centreline Douglas fir keel. An aluminium crossbar near the aerodynamic centre gave the frame some rigidity. A fixed, triangular trapeze (an 'A' frame control bar of metal tubing that is still widely used today) was attached to the crossbar, together with a freely suspended webbing harness for the pilot. The tether to the boat can be seen attached to the control bar of the A-frame.

    The forward motion for the kite was provided by the boat until the tether was released. Height and direction, relative to the boat, was controlled by shifting the pilot's body fore and aft and/or side to side (and thus the centre of gravity) relative to the fixed A-frame control bar, to change the kite's pitching and rolling moments; using the pendular weight-shift control system. Bill Moyes was captivated by the utility of the system and around 1967, using a Dickenson wing, he acquired the world altitude records for such vehicles. Bill Bennett was a witness to the records, riding in the aircraft that flew alongside to confirm altitude.
    John Dickenson flying the Mark 3 version of his wing. Grafton, Australia 1965.
    The Dickenson wing and the pendulum body support plus the wing control frame weight-shift system has developed into an aircraft design that has not only been used for perhaps 90% of all foot-launched hang gliders made since, it is also the basis from which the aircraft generally known as 'trikes' in Australia and the USA ('microlights' in Europe) have been developed. Unfortunately there has been little recognition, in Australia and internationally, of the enormous contribution made by John Dickenson's wing and the weight-shift control system (but see 1996 and 2006). A big advantage of the A-frame control bar is that the pilot has a direct feel for how the wing is flying — there are no intervening control rods, cables or pulleys connecting control surfaces to the pilot.
      1969 Bill Moyes went to Europe with the barefoot water ski team for the world water ski championships in Copenhagen, and took a hang glider for demonstration. Bill Bennett moved to America and demonstrated the Dickenson wing to the USA by flying a tow-launched aircraft around the Statue of Liberty on Independence Day. Bill Bennett did much to promote hang-gliding, particularly in the United States; it is sad to report he died aged 73 on 7 October 2004 following engine failure after take-off in a trike at Lake Havasu City, Arizona, USA.

    For a while it looked as though self-launching, powered hang gliders with a wheeled undercarriage were likely to be the way to go, however the early 'paper-dart' type wings had a number of problems and many people around the world returned to a more conventional wing and tailplane/canard designs, some utilising the single-surface sailcloth covering of the hang glider.

    (The continuing development of those early tow-launched and the later foot-launched hang gliders went on to produce a strong national and international competitive hang gliding scene, even to the extent of fitting small, back-pack engine and propeller units to the hang glider pilot's harness — powered hang gliders. And, of course, the development of the weight-shift control trike continued — and still continues.)

    2. The three-axis control, minimum aircraft years: 1974–1982
    1974 – 75 Ronald Gilbert (Ron) Wheeler, a catamaran builder and hang glider builder of Sydney, Australia, fitted an 8 hp 180 cc Victa lawnmower engine to his Tweetie tapered wing, tailplane-equipped, hang glider and undertook the first flights of his Scout Mk1 in June 1975; starting production of this aircraft soon after. The Scout was the world's first commercially available powered 'minimum' aeroplane — semi-rigid wing similar in concept to a yacht sail. The aircraft now incorporated normal three-axis control (rather than weight-shift control) utilising rudder and elevator control surfaces for yaw and pitch, and wing warping for lateral roll.

    The early design was an extremely basic machine, a publication describing it as 'the ultimate in simple tube and Dacron design'; initially utilising standard yacht fittings from the local marine shop. The design incorporated a cambered, single-surface, sailcloth wing (rather than a full aerofoil wing), yacht mast tubing as the leading edge spar, and was easily transportable. This original Scout was underpowered but nevertheless, on a good day, it usually flew. The Skycraft Scout Mk2 was a factory-built minimum aircraft with an 11 hp, one-cylinder Pixie Major engine, empty weight 49 kg, maximum speed 42 knots and endurance about 40 minutes. The Scout started a new Australian industry.

    1976 – 79 Ron Wheeler's persistent pursuit of the authorities to exempt minimum aircraft from the existing air navigation orders — and thus legalise the flight of his Skycraft Scout — influenced the Australian Department of Transport to issue (October 1976) an Air Navigation Order under which the minimum aircraft could legally be operated. Thus was created the world's first powered ultralight legislation. ANO 95.10 later CAO 95.10, legalised the manufacture and operation of the Scout and its many fellows, and paved the way for the most significant advance in Australian private flying since the aftermath of World War 2. However, there was no requirement for minimum aircraft to be registered, or for pilots to be licensed — although quite a number of people with general aviation licences were minimum aircraft enthusiasts — and there were no defined airworthiness, design or piloting standards; indeed most enthusiasts had to teach themselves how to fly.

    The Skycraft Scout (that sold for about A$1800) and the enabling legislation, fired people's imagination and commenced a revolution in Australian powered minimum aircraft aviation. Ron Wheeler alone sold 200 of his Scout Mk2 and then released the Mk3 pictured above with an 18 hp Robin engine (empty weight: 59 kg, stall speed: 18 knots and available with Wheeler-designed floats) and many other variations. Clubs sprang up in Australia, and the world, and all sorts of new design aeroplanes entered an expanding minimum aircraft market. Colin Winton, one of the many Australian enthusiasts, introduced his streamlined Grasshopper and later the Cricket, the first of a line of excellent aircraft from Col Winton and his son, Scott Winton.

    Gareth J Kimberley — RAAF and Qantas pilot — designed the very successful 1977 Sky Rider, a plans-built, three-axis aircraft with a single-surface sailcloth wing, conforming to ANO 95.10 and, in April 1978, founded the Minimum Aircraft Federation of Australia (MAFA) as the conduit through which the Department of Transport and part of the minimum aircraft community communicated. MAFA became the Minimum Aircraft Flyer's Association in 1982. Gareth published 'Fun flying! : a total guide to ultralights' in 1984.
    CAB Wasp: designed by Neville White in 1978 after purchasing a Scout which he found unsuitable. He built sixteen of the aluminium tube and sailcloth CAB Wasps. Neville — honoured as a Pioneer by RA-Aus in 2008 — is a member of the Holbrook Ultralight Club. Photo courtesy of Max Brown of the Australian Ultralight Aircraft Museum. For a description of the aircraft read an assignment (MS Word document) on the CAB Wasp that Max Brown wrote in 2009 as part of a Museum Practice course.
    Unfortunately the Australian Government regulations, though certainly enlightened for the times, restricted all flight operations to heights below 300 feet above ground level (agl) — to keep minimum aircraft operations below the 500 feet minimum operating height for general aviation aircraft. The aircraft were required to be single-seat, with a maximum empty weight of 115 kg, maximum empty-weight wing loading of 11 kilograms per square metre (2.25 pounds per square foot), maximum fuel load 15 kg, and were prohibited from flying within 300 metres of a public road or within 5 km of an airport. Basically the airframes were made from 50 or 60 metres of thin-walled aluminium tube and perhaps 35 square metres of sailcloth, and a lot of steel wire/cable. They were initially fitted with unreliable, under-powered, two-stroke engines — even chain-saw and mower engines — but quickly advanced to specifically designed engines with more capability. Such aeroplanes generally incorporated full three-axis control, but a few hybrid machines utilised a suspended, webbing pilot seat just for weight-shift pitch control.

    The 300 feet height restriction in the first edition of ANO 95.10 (slightly increased in 1985 to 500 feet); though reasonable at the time because of the lack of climb performance (some were difficult to get out of ground effect), was certainly not a pragmatic one, in the light of the subsequent (and unanticipated) rapid development in minimum aircraft capability. With their very light empty weight many aircraft had poor engine-off glide performance ratios with a heavy pilot on board — sometimes as low as 3:1; i.e. maximum wings level distance that could be flown, following engine failure at 300 feet, was 900 feet in nil wind conditions; a bit of a problem when you need a cleared area, with no livestock, quickly. Wind, manoeuvring flight and turbulence decreased that distance considerably. Also the first several hundred feet of the atmospheric friction layer are the most turbulent part of the lower atmosphere and particularly subject to wind shear events. And many of the pilots were self-taught.

    There was another aspect in that, although ANO 95.10 exempted the minimum aircraft movement from some provisions of the Air Navigation Regulations (now Civil Aviation Regulations), much of the regulations were still applicable. It seems that the authorities of the day may have turned a blind eye to minimum aircraft operations (perhaps believing that the movement would be a short-lived phenomenon) with undesirable results.

    The Australian Ballooning Federation (ABF) was formed in 1978 to administer recreational, adventure and competitive (FAI*) lighter-than-air private hot-air balloon flying. The Hang Gliding Federation of Australia [HGFA] started in 1973 as 'The Australasian Self-Soar Association' (TASSA) changing to HGFA in 1978 to provide one national body controlling all hang-gliding activities. HGFA now administers hang-gliding and paragliding (including powered variants with no more than 70 kg empty weight) and also powered, weight-shift control microlights/trikes. (In 2010 HGFA had 2300 members, 48 flight schools and 44 clubs located throughout Australia.)

    *Founded in 1905, FAI (Fédération Aéronautique Internationale) is the international governing body for air sports and aeronautical world records.

    Bill Moyes was awarded the FAI's 1979 Hang Gliding Diploma. This may be 'awarded every year to an individual who is considered to have made an outstanding contribution to the development of hang gliding by his or her initiative, work or leadership in flight achievement'.
    The Stolero: Steve Cohen's and Frank Bailey's 1978 design. Three-axis control with a mostly single-surface, wire-braced wing; later modification produced the Condor. Photo courtesy of the Australian Ultralight Aircraft Museum.
    3. The AUF strides onto the stage: 1983–1984
    1983 The Australian Ultralight Association was formed in 1982 and renamed the Australian Ultralight Federation during the Sports Aircraft Association of Australia's [SAAA] Easter 1983 convention at Mangalore. Although originally conceived as simply a peak honorary body for ultralight clubs — in much the same way as the Gliding Federation of Australia* was organised — it soon became apparent that ultralight fliers were not interested in this arrangement, probably because of the basically independent nature of ultralight aviation. Within 18 months some 700 persons had joined the new Federation, not via a club but as individual members.

    *Note: gliding began in Australia around 1929; the Gliding Federation of Australia [GFA] was formed in 1949, and initiated the concept of self-administration of sectors of aviation. Australian gliding became 'self-regulating' in 1953. The nature of gliding is very much a group activity rather than an independent operation of an individual pilot.

    Around this period it became evident to the Commonwealth Department of Aviation* [DoA had supplanted DoT] that these sport and recreational aircraft were here to stay and heavier, more complex ultralights would be developed; so something would have to be done to formalise the movement and do something about the very poor safety record. DoA cast about for someone to bite the bullet and accept ownership of the burgeoning ultralight movement that was developing from the minimum aircraft base. There had been a battle for some time over which single body would be the national representative of ultralight aviation in its dealings with the Department; there were several contenders but the Minister for Aviation recognised the AUF (rather than SAAA, the other major contender) as the national body.

    *Note: the primary function of the air regulations is to achieve safety in aviation. Under the Air Navigation Act and other legislation, DOA's regulatory function was the "formulation, implementation and oversight of operational standards and procedures for the safe conduct of flight operations".

    The Thruster Aircraft factory, at Kirrawee and later at Evans Head, commenced manufacture of single-seat Thrusters with 46 being built in 1983. The aircraft was a Steve Cohen development of his and Frank Bailey's 1977–1978 Stolero/Condor designs.

    1984 The AUF received its Certificate of Incorporation and signed a Services Agreement with DoA to assist the Department to set, implement, monitor and enforce standards for ultralight aviation (comprising powered minimum aircraft with an empty weight exceeding 70 kg) including the establishment and maintenance of a pilot certification system, production of a training and operations manual and the issue of pilot instructor certificates, for which an annual 'Grant-in-Aid' would be provided to perform the administration work that otherwise would have to be done by the Department.

    Work proceeded on the necessary systems and procedures and the essential AUF Operations Manual, which was released in 1986. Also the formats for new air navigation orders were being developed to provide two-place ultralights for training purposes; ANO 95.55 was to be the operational standard, ANO 100.55 was to be the aircraft maintenance standard and ANO 101.55 was to be a full airworthiness certification standard for commercially manufactured ultralight aeroplanes. (ANO 100.55 was never tabled as its purpose would eventually be fulfilled by the AUF technical manual.)

    There was an expectation amongst builders of ANO 95.10 aircraft that a new ANO (95.22) would soon be released allowing a maximum aircraft empty weight of 150 kg instead of the 95.10 115 kg, consequently most aircraft being built weighed up to 150 kg. A dispensation was provided to the owners of the overweight aircraft allowing continuation of operation, but the introduction of ANO 95.55 was consequently delayed for several years.

    The effort that the early AUF volunteer office bearers contributed was incredible, inheriting this big pool of enthusiastic flyers, who in many cases, knew little about aviation and, anyway, didn't want to. Unfortunately, the accident rate was making people sit up and take notice. (The Bureau of Air Safety Investigation accident data for the period 1978–1986 indicated 77 accidents involving ultralights and causing 35 fatalities and 28 serious injuries.)
      It is easy to be critical of those early years, however we should not forget that all flight operations were legislated to be below 500 feet agl with the inherent danger of forced operations at very low heights (something now considered unthinkable). This was exacerbated by aircraft with extremely limited flight envelopes (for example, only a 15–20 knot (30–40 km/h) range between minimum and maximum controllable airspeeds) and with occasional stability problems.

    To compound the problem, it was still illegal to be taught how to fly in a two-seat ultralight and most would-be pilots had to teach themselves in their newly-built single-seat aircraft!

    The regulations were forcing ultralight aviation to operate in a regime where any sort of stall, not quickly recovered — because of a lack of supervised training in two-place aircraft — was almost certainly going to finish up as an accident. In general aviation training the recommended minimum height for practising stall recovery was then 3000 feet agl.

    About this time Frank Bailey, an aircraft production engineer, published his popular book on how to teach yourself to fly a minimum aircraft. The book explained all that was needed; from basic aerodynamics in simple terms to choosing a paddock from which to operate. The book cover indicates that the definition of a paddock was somewhat loose in those earlier days — the two B1-RD minimum aircraft are operating from a rather rough, dry creek bed; note that registration marks had not yet appeared.
    Photo courtesy of the Australian Ultralight Aircraft Museum, Holbrook, NSW.

    4. Taking powered sport and recreational aviation in hand — training aircraft and flight schools: 1985–1986
    1985 The AUF membership reaches 850. DoA promulgated ANO 95.25* as a second regulatory class covering single-place and two-place factory-built ultralights. This ANO was introduced as an interim means (until ANOs 95.55 and 101.55 were promulgated) for providing approval of two-seaters, built to a defined airworthiness and design standard, and to allow their use as commercial training aircraft — without full type certification — for the ANO 95.10 pilots. The ANO 95.10 regulatory class was still exempt from airworthiness or design specifications.

    This was a big step for Australian aviation generally and again a world first; but still an ultralight could not be flown at a height in excess of 500 feet agl. The legislation specified 370 kg maximum take-off weight [MTOW] inclusive of pilot and student weight; which was somewhat low as it was difficult to accommodate two people (at the standard mean weight of 77 kg each) plus around 25 kg of fuel in a stronger, thus heavier, airframe without exceeding MTOW – so it was later increased to 400 kg. A single-place 95.25 aircraft was limited to 290 kg MTOW. The reliability and availability of purpose-built two-stroke engines are improving, along with better engine and airframe performance.

    *Note: although the ANO 95.25 legislation was promulgated in March 1985, no aircraft had passed the certification package until March 1986. At January 1987 only two models of 2-seat training aircraft had been approved; the Gemini Thruster and the Hughes LightWing.
    The AUF received a $45 000 grant from DoA, covering a 3-year period, and was thereby enabled to set up training curricula; encourage the establishment of facilities for ultralight flight training, (both within the clubs and as commercial entities); nurture their continuing existence and maintain a safety watch over their operations and abilities. An ANO 95.10 amendment required that any person operating an ultralight be an AUF member.

    The approval of the AUF Operations Manual by DoA in effect issued an Air Operator's Certificate (AOC) to the AUF covering all the AUF approved flight training facilities (FTFs). (An AOC authorises an organisation to conduct specified aerial work operations, flight training, air charter operations or regular passenger transport operations.) DoA devolved the task of assessing, approving and subsequently auditing each flight training facility, against the provisions of the Operations Manual, upon the AUF Operations Manager.

    Around this time ANO 95.10 was changed to exclude commercially manufactured aircraft. This effectively stopped the factory manufacture of the single-place minimum aircraft, except for home-building from factory-supplied kits, and changed the concept of Australian ultralight aviation.
      1986 Having completed a formal ultralight flight training course, AUF Pilot Certificate no. 1 was issued in March to Bill Dinsmore, the first AUF Operations Manager and the author of the initial Operations Manual.

    The AUF aircraft register was established and the first aircraft issued with an ANO 95.25 type acceptance certificate — the Thruster Gemini two-seat trainer prototype — was registered as 25-0001 in early 1986.

    (Note: Thruster 25-0001 was still flying in 2007 but under another registration number though there was a campaign underway to restore the 20-year old aircraft to its original and historical registration that had been usurped by another aircraft, but the principal leader of the campaign — Tony Hayes (the inaugural holder of the RA-Aus Meritorious Service Award) — died in 2009.)

    By 1986 Thrusters had already been demonstrated overseas at the Paris Air Show and at Oshkosh, USA with export already underway in 1985. With the authority of ANO 95.25 backing it, export really got going the following year and an Australian-owned subsidiary Thruster factory opened in the UK. The process led to the construction of over 700 Thrusters in many models with versions still entering the market in 2001.

    5. HORSCOTS reinforces the AUF administration of ultralight aviation and introduces international design standards: 1987–1989
    1987 The AUF membership is now 1150. In January the HORSCOTS (House of Representatives Standing Committee On Transport Safety) 'Report on Sports Aviation Safety' (8.5 MB pdf file) confirmed that Ultralight Aviation should continue to be administered by the AUF, recommended that height ceilings should be raised, affirmed the requirement for two-place trainers and mandated that all factory-built or kit-built three-axis ultralights accord with the new design and certification standard, ANO 101.55, being developed for aircraft up to 450 kg MTOW and subsequently promulgated in January 1988.

    HORSCOTS directed the Authority that funds be made available to the AUF to assist the Authority to set and monitor standards for ultralight aeroplanes and operations. There was no funding provided for the mandatory functions performed to administer the aircraft register, the pilot and instructor certification systems and the appointment of Chief Flying Instructors. The report also recommended that 'legislation be changed to legalise spin/stall training for ultralights and that spin/stall training in 2-seat aircraft be incorporated into the flight training syllabus of student pilots'.

    The HORSCOTS report introduced the term 'Light Sports Aircraft' (note the plural) to describe aircraft now known as 'sports and recreational aircraft'.

    1988 ANO 95.10 was amended to allow an 150 kg empty weight and 290 kg maximum take-off weight.

    All the ANO designations were then changed to CAOs; i.e. Civil Aviation Orders when the Civil Aviation Act 1988 was introduced, establishing the Civil Aviation Authority from the DoA. However, as can be seen in this extract, the Act did not devolve upon CAA, or subsequently CASA, any function relating to the on-going development, or indeed the survival, of civil aviation – in any of its forms. There is no Australian government authority with any function relating to such matters with respect to recreational aviation. In the USA the Federal Aviation Administration includes the words "to foster and support all forms of aviation" in its mission statement.

    However CAA (and later CASA) have done much, through legislation and attitude, to encourage the building (and maintenance) of 'experimental' ultralights by individuals and of 'type certificated' ultralights by commercial enterprises; and to devolve the management of ultralight affairs to the AUF/RA-Aus.

    By 2002 it was obvious that together AUF/RA-Aus and CAA/CASA had put in place one of the best, if not the best, system of very light aircraft training in the world.
    Bantam B22S. The original B22 was designed and manufactured in New Zealand around 1987; production of the CAO 101.55 certified Bantam B22S training aircraft commenced in 1995. Photo of 24-3221 courtesy of Max Brown of the Australian Ultralight Aircraft Museum.
    6. Introduction of non-training two-seaters: 1990–1992
    1990 The AUF membership is now 2400. CAO 95.32 was released in February as an operational standard providing exemption — for weight-shift controlled aeroplanes (to be registered with the AUF or HGFA) and powered parachutes (to be registered with the AUF) — from some provisions of the Civil Aviation Regulations. CAO 95.55 was released in August as an operational standard providing exemption (for certain single-engine ultralight aeroplanes to be registered with the AUF) from some provisions of the Civil Aviation Regulations.

    The CAO 95.55 aeroplanes were factory-built or amateur kit-built (ABAA) 450 kg MTOW two-seat aircraft built to the design standards and certification requirements of CAO 101.28 or the previously mentioned CAO 101.55. (ANO/CAO 101.28 was introduced in 1976 to aid amateur building of SAAA aircraft.) A CAO 101.55 factory built ultralight could be registered as a general aviation aircraft, if fitted with a certified four-stroke engine, navcom equipment and additional instrumentation. CAO 95.25 was then cancelled but did not prohibit the continuing manufacture of the 6 or 7 types already accepted under CAO 95.25.

    The maximum altitude for flight operations was increased to 5000 feet amsl (or 2000 feet agl over high terrain) and at last specified a minimum operating height of 500 feet agl – except when taking-off or landing.

    Around this time, after several years negotiation, the AUF, particularly represented by John Baker*, was successful in amending CAO 95.10 to allow construction of single-seat aircraft from approved commercial kits. This gave more people access to ultralighting who had neither the time nor skills to design and build their own aircraft or build from plans. Aviation took another step toward being more accessible to more people. With the wide introduction of the 95.25 two-seat trainers, and formalised training, the safety record turned the corner for the better. (And has been steadily improving ever since: the average annual fatality rate during 1996 – 2000, per 1000 registered ultralights, was only 10% of the rate in the years preceding HORSCOT.)

    *John Baker was the Airworthiness (now Technical) Manager from about 1984 to 1994 and it was his efforts that produced the first edition of the Technical Manual in 1993. John's day job was as Wing Commander John Baker, RAAF, officer commanding the RAAF's Aircraft Research and Development Unit.
      1991 The Jabiru Aircraft Company, of Bundaberg, Queensland, that was formed in 1988 to develop a fibreglass-reinforced epoxy polymer fabricated ultralight, received type certification under CAO101.55 for their Jabiru LSA 55 two-seat 'light sports aircraft' ultralight. The aircraft was then available as a factory 'fly-away' or as a kit for home-builders. This ultralight aircraft proved to be so successful that it is now (written in 2003) popular with general aviation flight schools, who otherwise have to be content with continuing to operate very old Cessna and Piper training aircraft, or spend extremely large sums for a new aircraft coming from the now severely curtailed production lines in USA.

    Around this time Aerochute Industries of Melbourne — following release of their single-place parawing aircraft in 1990 — introduced their highly successful two-place powered parachute, that went on to dominate the Australian market for such aircraft.

    7. The consolidation years: 1993–1997
    1993 The AUF membership is now 3300. The AUF campaign for further increases in aircraft weight resulted in an increase to 480 kg MTOW for cabin-type two-seat trainers, allowing opportunity for the heavier four-stroke engines and an advance in reliability with such engines. Two-stroke engines, particularly those from Bombardier-Rotax, had now evolved to be viable power plants, but still prone to stoppages without any warning signs.

    An innovative Jabiru Aircraft r&d program produced the light-weight Jabiru 1600 cc, 60 hp, four-cylinder, four-stroke engine to replace an imported engine. Jabiru '1600' powered aircraft were manufactured from 1993 to 1996, when a 2200 cc 80 hp version went into production. (Jabiru later introduced a 3300 cc six-cylinder engine version.)

    1994 The AUF has now been in existence for 11 years. The following extract from the Department of Transport and Regional Services' 'Digest of Statistics, 1994' recognises the contribution of the AUF to Australian Aviation.

    "The ultralight movement represents a return to the minimum aircraft, or 'grass roots' concept of powered flight. In October 1976 the Australian Government, through the then Department of Transport, introduced the world's first legislation covering the operation of ultralight aircraft. The Australian Ultralight Federation was incorporated in 1984 to oversight the operation of ultralight flying activities.

    The initial restrictive legislation has since been progressively relaxed, to the extent that ultralight aircraft can now compete directly with 'conventional' aircraft in some aspects of the leisure flying and training markets.

    The popularity of the sport has led to a thriving and innovative Australian light aircraft manufacturing industry.

    Although no statistics are available for the earlier years, it is noteworthy that the industry has grown from virtually zero in 1976 to one involving more than 1100 aircraft flying nearly 73 000 hours in 1994."

    1995 –1996 Additional safety was achieved when CAO 95.55 issue 2 allowed radio-equipped ultralights to operate above 5000 feet when "flying over an area of land, or water, the condition and location of which is such that, during the flight, the aeroplane would be unable to land with a reasonable expectation of avoiding injury to persons on board the aeroplane."

    Airborne Windsports Pty Ltd, of Redhead NSW, received their CAA Certificate of Approval for manufacture of aeroplanes. The company first set up operations in 1983 as a hang glider training school. In the early 1990s, Airborne designed and produced the first of what later proved to be a highly successful — both nationally and internationally — range of powered, weight-shift trikes, the Airborne Edge. Most of the company's early production was registered with HGFA, probably due to their exposure to HGFA members as hang glider tugs; the first AUF registration was recorded in 1992.

    The Civil Aviation Safety Authority (CASA) was created in July 1995 by splitting the Civil Aviation Authority into two parts — CASA and Airservices Australia (AsA). CASA was assigned the function of conducting the safety regulation of civil air operations in Australian territory.

    (It is interesting to note that later (2003) CASA was provided with a new Charter Letter setting out strategic directions for the organisation which included this paragraph: "The Government's vision for CASA is of a firm but fair regulator which focuses on core safety related functions in a way that ensures that industry meets its safety obligations, but at the same time permits development and growth in Australian aviation." This goes some way to redressing the shortcoming mentioned earlier that there is no Australian government authority with any responsibility relating to to the on-going development, or indeed the survival, of civil aviation – in any of its forms.)

    In 1996 John Dickenson was awarded the Medal of the Order of Australia 'In recognition of service to flying, through the invention of the 'Delta Ski Wing' and to the development of hang-gliding, paragliding and the microlite aeroplane'.

    There was little growth in AUF membership during 1993 through 1997; new members joining matched normal attrition so total membership remained stagnant at around 3600 voting members.

    8. Amateur-built (experimental) regulations establish a new platform for growth: 1998–2000
    1998 CAO 95.55 was expanded to allow a category of 'Amateur-built (Experimental)' and allowing an increase to 544 kg MTOW for two-seat aircraft to cater for newer, more reliable, four-stroke engines; more robust airframe design; a less demanding nosewheel rather than tailwheel configuration, thus providing more consistently safe landings; and an increased fuel capacity providing a longer and safer airborne endurance plus the ability to take a friend along for the ride. Consequently the number of new single-place aeroplanes entering the AUF Register started to decline while the number of two-place machines increased at a fast pace.

    Each advance of MTOW, negotiated between the AUF and CAA/CASA over the years, while still restricting the seating capacity to pilot and one passenger, has made for a range of safer, stronger Australian-manufactured aeroplanes that appeal – in terms of the hip pocket and reliability and ease of handling – to a much wider recreational community, and thus encourages interest in Australian sport and recreational aviation and revives growth, while still preserving the minimum aircraft concept on which the AUF was founded.

    1999 In a low period in CASA/AUF relations, lobbying by the association caused the Senate to disallow tabled changes to CAO 95.55 that would have been detrimental to the members.

    9. The AUF enters its third decade and becomes RA-Aus: 2001–2004
    2001 Membership increased to 4500. CASA issued NPRM 0115SS which proposed that each AUF flight training facility must hold an Air Operator's Certificate (Sport Aviation), appoint a Chief Pilot and be audited periodically by CASA on an hourly charge plus travel basis. The costs involved and the problems associated with the FTFs being supervised by two organisations made untenable the positions of the (necessarily smaller) schools in regional areas. After a struggle the proposed changes were not implemented.

    Number of AUF registered ultralights, by category, 1993 to 2001 (Fiscal Year)
    Year CAO
    95.10 CAO
    95.25 CAO
    95.55 CAO
    101.55 CAO
    95.55 CAO
    101.28 'chutes trikes sub-total
    exc. 95-10 total   Commercially built Amateur built Weight shift               1993 586 345 .. 89 .. 34 31 13 512 1,098 1994 519 355 .. 118 .. 48 46 14 581 1,100 1995 501 364 .. 151 .. 72 64 14 665 1,166 1996 494 379 .. 167 .. 93 71 18 728 1,222 1997 469 385 .. 196 .. 114 67 23 785 1,254 1998 470 388 .. 209 .. 139 74 25 835 1,305 1999 458 386 10 214 88 136 69 36 939 1,397 2000 439 366 44 227 186 135 79 46 1,083 1,522 2001 398 332 65 209 286 131 76 47 1,146 1,544
    2004 AUF registered aircraft are formally accorded Australian nationality under the terms of the Chicago Convention on international civil aviation; which is relevant in ensuring that RA-Aus aircraft are not discriminated against by Australian aerodrome operators. Previously AUF aircraft were more or less legally 'stateless'. The change also closed a loophole in the application of the civil aviation regulations to RA-Aus aircraft.

    The twenty one years that the AUF has been in existence has seen a major expansion in the types of aircraft on the AUF Register, but still at the heart of the light aircraft movement in Australia – as elsewhere – are those amateur builders who assemble their aircraft at home from a factory-supplied kit; or fabricate it from basic plans. Or those really dedicated individuals who build and fly their own designs. Such aircraft first registered in the CAO 95.10 category — the low-momentum ultralight aeroplanes — are still the heart of ultralight aviation even though they now represent less than 15% of registrations. Trikes from Airborne Australia and powered parachutes from Aerochute Industries are still maintaining a significant share of new aircraft registrations. Airborne received their CASA Type Certificate and Production Certificate for the Airborne XT range.

    However the availability of a wide range of structurally stronger ( thus heavier) and faster commercially-engineered aircraft (some of which may also be registered with CASA as general aviation aircraft); equipped with engines of much greater reliability and capable of travelling longer distances (even non-stop from Australia to New Zealand), is encouraging many more people — of all ages — to take up flying. A surprising number of new members are middle-aged persons who have always thought they would like to fly and now, being relatively free of family commitments and work pressures have reduced somewhat, are realising that ambition.

    So, over 21 years ultralight aviation and the highly successful AUF grew, from a few hundred somewhat intrepid and usually self-taught aviators, to a more general — and rather more cautious — membership of 5300 with the number of aircraft on the register in October 2004 nearly doubling the 1994 register. To reflect this broadening of the ultralight aviation community, in April 2004, the Australian Ultralight Federation changed its name to Recreational Aviation Australia Incorporated (RA-Aus).

    All this from the humble beginnings of towed Dickenson kites and the Wheeler Scout, through 21 years of the AUF to an era of safe, affordable recreational aviation. It is interesting to note that on 1 September 2004 the United States Federal Aviation Administration introduced the Sport Pilot Certificate (and the Light Sport Aircraft category) for recreational and sport aviation that, if you didn't know better, might be thought to be very much modelled on the RA-Aus Pilot Certificate and the CAO 95.55 concept. RA-Aus is continuing to work with CASA on the introduction of new and simpler regulations.

    10. The remarkable RA-Aus growth takes off: 2005–2009
    2005 The success of the Association is the best thing that has happened to private powered flying in Australia since World War 2. Due to the dedication and diligence of the staff and board members, in 2005 the Association was well positioned to build on that success.

    The year concluded with several noteworthy milestones occurring in December. The number of current RA-Aus flight schools passed 100, the current paid-up membership reached 5996 (12% increase in 12 months), the Jabiru Aircraft Company delivered the 1000th aircraft in its Jabiru range — to an FTF at Swan Hill, Victoria.

    The work for the enabling legislation for light sport aircraft [LSA] categories to be added to CAO 95.55 and CAO 95.32 was completed and, commencing from 7 January 2006, RA-Aus registration of LSA aircraft with the maximum weight of 600 kg for landplanes and 650 kg for seaplanes was then allowed. LSA applies equally to general aviation and recreational aviation so that the boundary between these two powered aviation communities is becoming increasingly indistinct and suggests that the numbers of GA flight schools also opting for RA-Aus FTF accreditation will increase.

    The Association purchased Canberra office premises to provide better staff facilities and room for expansion.

    2006 John Dickenson was awarded the 2006 Fédération Aéronautique Internationale Hang Gliding Diploma. The citation reads:
    'John Dickenson invented the modern hang glider at Grafton, Australia. It was flown on 8 September 1963. John built scale models to determine design concepts, until a full sized glider was towed behind a speedboat. He incorporated the control bar into the airframe by designing the A-frame to distribute flight [loads?], refining this further when he invented the pendulum weight-shift control system. John developed the piloting techniques, and taught all the early pilots, including Hang Gliding pioneers Bill Moyes and Bill Bennett, to fly the wing. John Dickenson's invention has been copied by every manufacturer globally, with few minor changes for over a decade'.

    While Australian general aviation still appeared to drift in the doldrums, Recreational Aviation Australia continued to forge ahead. Membership at 31 December 2006 was 6946, up 16% from the 5996 at 31 December 2005, the highest increase achieved between 1990 and 2010. The number of RA-Aus approved flight training facilities increased by 13% during 2006, totalling 113 at 31 December.

    During the year 348 new registrations and re-registrations were added to the RA-Aus aircraft register. Trikes — mostly from Airborne Australia — represented 15% of new registrations and powered parachutes — all from Aerochute Industries of Melbourne — represented 10% which indicates the annual growth rate for those categories is somewhat higher than the three-axis category.

    RA-Aus fees and charges were increased for the first time in nine years — apart from the GST impost.

    The 2006 year saw the 20th anniversary of the issue of the first AUF Pilot Certificate.

    Regulatory environment
    CASA extended operations in Class E VMC airspace to RA-Aus Pilot Certificate holders.

    On 21 December 2006 CASA published NPRM 0603OS, the notice of proposed rule making relating to the pending introduction of the long debated CASR Part 103 'Sport and Recreational Aviation Operations', that will make redundant the current exemption CAOs under which sport aviation operates. CASA had a target implementation date of first quarter 2007 for issue of the NPRM for the related CASR Part 149 that will define the role of recreational aviation administration organisations.

    2007 The year brought, to recreational aviation, a mixed bag of continuing progress and major disappointment.

    Foremost was the RA-Aus safety record, which for the first 10 months was disappointing enough in that 2007 was shaping up to be just another average year rather than an improvement, but the occurrence of three fatal accidents during the last six weeks of the year brought about a distressing reversal in the safety record. There were eight fatal accidents in 2007 in which eight pilots and five passengers died. In addition there were two other accidents where occupants were severely injured. Passengers died in nearly two-thirds of the fatal accidents, whereas the recent history has been a passenger fatality in one-third of the fatal accidents.

    Growth in RA-Aus numbers
    Voting membership at 31 December 2007 was just on 7800, up 12% from 2006. A total of 402 flying instructors, senior instructors and CFIs are included in the membership figure.

    The number of RA-Aus approved flight training facilities increased by 13% during 2007, totalling 128 at December 31. In addition, there were about 10 satellite FTFs controlled by the CFI at a 'parent' location until a permanent onsite CFI is available. During the past three years the FTF growth rate has been healthy and consistent. Part of the growth is derived from general aviation flying schools opting for association with RA-Aus thus expanding their potential market.
    RA-Aus aircraft register

    During the year 346 new registrations and re-registrations were added to the aircraft register. CASA's aircraft register is appoaching 13 000 aircraft.
    Regulatory environment

    The long-awaited legislation for CASR Part 103 was not promulgated as hoped. Eleven years had elapsed since work on this Part and Part 149 started in 1996 — obviously the mills of regulatory change grind very slowly when associated with Australian recreational aviation. However in July 2007 CASA did publish another notice of proposed rule making NPRM 0704OS, relating to the introduction of CASR Part 149 'Sport and Recreational Aviation Administration Organisations'. This NPRM was the second related to Part 149, the previous notice of proposed rule making — NPRM 9805RP — was published in 1998 but never got anywhere.

    2008 The year was very rewarding in terms of the primary goal — safe flying. There was only one fatal accident in an RA-Aus registered aircraft during the year — sadly both occupants died. There were no accidents where long-term injuries were sustained. Since the AUF/RA-Aus was established in 1983 there has been one other year (1996) where only one fatal accident occurred. Ordinary membership at 31 December 2008 was 8440. So, considering the 145% increase in membership since 1996, 2008 was the safest RA-Aus flying year ever. The average annual number of RA-Aus fatal accidents for the five-year period 2004–2008 is 4.5 — about the same as the 1999–2003 period.

    Past history shows that 87% of RA-Aus accidents involve — or are directly attributed to — critical decisional errors or human factor (HF) related events. Elimination of such events might be regarded as the last frontier to be conquered in the quest for fatality-free operations. HF training of the instructor population commenced in 2007 and, by end 2008, over 70% of instructors had completed a human factors related course. HF training was added to the RA-Aus Pilot Certificate training syllabus with the introduction of a revised Operations Manual. Consequently, from August 2008 all new pilots study HF in their training. All existing Pilot Certificate holders were required to complete an HF course, or an examination, by August 2010.

    RA-Aus aircraft register
    During the year 312 new registrations and re-registrations were added to the aircraft register, with a number of older aircraft dropping out, bringing the total to 2805 aircraft at December 31, 2008.
    State Full
    registration Provisional
    registration 90-day
    suspension Total Qld 704 23 26 753 NSW + ACT 706 26 16 744 Vic 624 20 17 661 Tas 79 1 2 82 SA 263 6 5 274 WA 224 10 2 236 NT 50 0 5 55 Total 2650 82 73 2805
    Note: RA-Aus provisional registration applies to completed home-builts that have not yet flown the 40 hours required for full registration. The 90-day suspension category applies to aircraft where the annual fee is up to 90 days overdue. After the 90 days grace period the registration entry is cancelled.

    The ratio of voting members to registered aircraft has hovered around 2.5:1 for some years but at the end of 2008 it had drifted up to 3:1. The average annual hours flown (in RA-Aus aircraft), currently reported by Pilot Certificate holders, has reduced a little to 32 hours; perhaps indicating that the average RA-Aus aircraft, including the training and club-owned fleet, flies about 100 hours per year.

    Growth in RA-Aus numbers
    Membership at 31 December 2008 is 8440, up 8% from the 7800 at 31 December 2007. The distribution of membership is:
    Queensland — 2139 (25%) New South Wales and the ACT — 2291 (27%) Victoria — 2093 (25%) South Australia — 927 (11%) Western Australia — 523 (6%) Tasmania — 278 (3%) Northern Territory — 119 (1.5%) Members currently overseas — 58 (0.5%) The number of RA-Aus approved flight training facilities increased by 9% during 2008, totalling 139 at 31 December. That total excludes about 15 satellite FTFs currently operating under the control of a parent FTF.
    Regulatory environment

    The non-promulgation of CASR Parts 103 and 149 remains a major disappointment. To curtail some of the effects, RA-Aus requested changes to the old exemption CAOs — 95.55, 95.32 and 95.10 for the introduction of:
    Entry to controlled airspace (with CASA requiring Class 2 medicals) Flight over water to come in line with GA requirements (not for powered 'chutes) Flight above 5000 feet approved in line with GA Entry to active restricted areas (dependent on conditional status) Consequently CASA established Project OS 08/13 'Early implementation of certain proposed CASR Part 103 standards via CAO'. It was expected that these changes could eventuate in 2009.

    2009 The year was very disappointing in terms of the RA-Aus primary goal — safe flying. It started very well; there were no fatal accidents in the first seven months and it looked like the RA-Aus human factors training programs were starting to produce the required results.

    Then there were four fatal accidents between August and December. Two of the accidents involved trikes, one of which was an unregistered aircraft. A passenger also died in one of the trike accidents. In addition, there was a fifth accident where an RA-Aus three-axis Pilot Certificate holder died in a trike registered with HGFA.

    So, a year that started with a lot of promise — following the gains made in 2008 — ended very badly. In effect, maintaining the historical average annual number of 4.5 fatal accidents.
    Growth in RA-Aus numbers

    Although there was no evident growth in safety effectiveness; throughout 2009 there was very healthy growth in membership, flight training facilities and recreational aviation clubs. At 31 December 2009 there were 9186 ordinary members; reflecting a net increase in numbers of 746 during the year.

    There was a net increase of 3936 members (or 77%) since the end of 2004. The increase reported is the sum of new members less the normal turnover of the existing membership during the period, so the number of new members added would considerably exceed the net increase reported.

    The number of RA-Aus approved and independently operating flight training facilities increased by 15 (10%) during 2009, totalling 154 at 31 December. That total excludes eight satellite FTFs currently operating under the control of a parent FTF.
    The number of known clubs associated with powered recreational aviation now totals around 106; again, a healthy increase during 2009.
    RA-Aus aircraft register

    Economic conditions seem to have affected the number of new aircraft registrations and the number of registration cancellations. The number of aircraft on the RA-Aus register at the end of 2009 was 2955; an increase of only 2% during the year.
    Regulatory environment

    The continuing non-promulgation of CASR Part 103 and CASR Part 149 is somewhat frustrating. This is exacerbated by CASA's October 2009 decision not to proceed with Project CS 06/01 'Proposed MTOW [750 kg] increase for aircraft operating under CAO 95.55'.
    As reported in 2008 CASA, at RA-Aus urging, established Project OS 08/13 'Early implementation of certain proposed CASR Part 103 standards via CAO'. Promulgation of that has also stalled in the legislative drafting; except that, in July 2009, the Director of Aviation Safety decided to maintain the current policy of entry into controlled airspace requiring a CASA Pilot Licence.

    11. RA-Aus growth begins to slacken: 2010–20??
    2010 There were three fatal accidents in RA-Aus registered aircraft during the year — sadly two passengers and two pilots died. The total number of fatal accidents in RA-Aus registered aircraft during 2008, 2009 and 2010 was eight or 2.7 fatal accidents per annum, an improvement on the average for 2004 to 2007 of 5.5 fatal accidents per annum. Considering the difference in average membership, and thus hours flown in the two periods, this provides a positive indication that the human factors training introduced in 2007 is taking effect.

    Growth in RA-Aus numbers
    The total ordinary membership at the end of 2010 — including non-voting juniors — was 9674; a net increase of only 488 members (or 5.3%) during the year. The reduction in rate of growth is due to an increase of about 350 persons (to roughly 1500) in the annual non-renewing numbers rather than to any reduction in the rate of recruitment. The annual intake of new members has been increasing slowly during recent years but, at the same time, the number of ordinary members not renewing membership has been increasing at a faster rate. A high and increasing member turnover, or perhaps poor early retention, is not a good sign.

    During 2005, 2006 and 2007 the total ordinary membership increased by an average of 830 persons (13% p.a.) each year. During 2008 the increase was 8% (640 persons) and 2009 was 9.5% (798 persons). During 2010 the increase dropped to 488 persons (5%) so the annual rate of membership increase peaked in 2006 at 16% and has been receding since then, though RA-Aus states that membership is expected to reach 10 000 ordinary members by December 2011. The total membership figure may start to decrease within a few years which may be a problem for the organisation's financing.

    The number of RA-Aus approved flight training facilities increased by 10% during 2010, totalling, at year end, about 170 schools operating from 190 locations. However a total of 454 flying instructors, senior instructors and CFIs are now engaged in flight training which represents a modest increase of 13% during the past three years.
    State Instructors Senior
    Instructors Chief Flying
    Instructors Total Qld 31 48 36 115 NSW+ ACT 40 52 44 136 Vic 22 47 29 98 Tas 2 4 6 12 SA 8 21 14 43 WA 4 20 16 40 NT 1 5 4 10 Total 108 197 149 454
    RA-Aus aircraft register
    The number of aircraft on the RA-Aus register increased by 261 aircraft (9%) during the 13 months since 31 December 2009. There were 350 new registrations or re-registrations in 2006, 342 in 2007, 315 in 2008, 247 in 2009 and 285 in 2010. During the last four years there has been a 11 percentage point shift away from home-builts (now 42% of total aircraft) towards increasingly complex factory-built aircraft. This has resulted in a substantial increase in the market value of the RA-Aus flight line — currently estimated at $115 million. This increase in market value is a worry as it restricts member acquisition of their own aircraft, which is reflected in the changing ratio of total members to total aircraft in the fleet. The lack of low price factory-built aircraft and kits is a negative factor.

    In the factory-built category, powered 'chutes and trikes continue to maintain their popularity amongst association members. Fifty per cent of the new aircraft added to the register came from the three larger Australian manufacturers; Jabiru added 84 aircraft (28%) — 13 of which were kit-built, Airborne added 44 trikes (15%) and Aerochute added 20 powered parachutes (7%). Airborne also supplies trikes to HGFA members so their total share of the Australian market is much higher than indicated by the RA-Aus registrations. Airborne is quite a success story, it has now manufactured some 2100 trikes, roughly equally distributed between local and international markets. (Note: the company's registered name is 'Airborne Windsports Pty Ltd', its name for marketing purposes was 'Airborne Australia' for some time, but now prefers to be identified as 'Airborne'.

    The ratio of total members to registered aircraft hovered around 2.5:1 for some years but it has been drifting up during the last few years and is now 3.0:1. However, the ratio of Pilot Certificate holders with endorsements to registered aircraft is probably more meaningful; this is currently 2.0:1.

    Regulatory environment
    CASA's Project OS 08/13 'Early implementation of certain proposed CASR Part 103 standards via CAO' has still not come to fruition but is expected in 2011, hopefully providing revised exemption CAOs incorporating the following changes:
    MTOW for landplanes (except low momentum ultralights) to be the lower of the aircraft's design or certificated MTOW or 600 kg. Flight over water rules relaxed. Flight below 10 000 feet approved.  
    2011 The year started very badly with two fatal accidents in January and continued in that vein throughout the year to total six fatal accidents. The death toll was eight — five certificated pilots, one student pilot under instruction and two passengers. There was also one ' collision with terrain' accident which did involve people on the ground and could have been horrific, but fortunately there were no serious injuries. The total fatal accidents for the five years 2007–2011 was 22 (4.4 per year) with 31 deaths. Recreational aviators are not improving quickly enough, see 'Decreasing your exposure to risk'.

    The chart below is the annual record of a 5-yearly average of the number of fatal accidents.
    Growth in RA-Aus numbers
    The total ordinary membership at 31 January 2012 — including 31 non-voting junior members — was 10 008; a net increase of only 334 or 3.5% from January 2011. The corresponding membership increase in 2010 over 2009 was 5%, 2009 over 2008 was 9.5%; 2008 over 2007 was 8%. The increase reported is the sum of new members enrolled (1956 in 2011) less the turnover of the existing membership during the period; that latter turnover was very high during 2011 totalling 1580 persons representing 16% of the membership at the beginning of 2011. Many of the persons who allow their membership to lapse will renew it in the following year, or later, after the circumstances that forced them to stop flying have improved. Such renewals of lapsed membership are not included as new members in the year of renewal.
    Some trend lines are added to this record of total membership (those with voting rights) from 1985 to the end of 2011. As you can see a period of stagnant growth existed during the five years 1994 through 1998. However, the 1998 introduction of the 'Amateur-built (Experimental)' category to CAO 95.55, fuelled an increasing interest in very light aeroplanes that resulted in six years (1999 through 2004) of moderate but sustained growth, where RA-Aus membership ultimately reached a seemingly critical mass of 5000 members. (The growth rate in the 1999-2004 period was similar to that in the 1988 though 1993 period.) The next five years, 2005 through 2009, saw a phenomenal expansion that increased membership by 77% to 9000. However this increase of 4000 members was not matched by a corresponding increase in aircraft ownership — the RA-Aus register increased by only 700 aircraft or 31% during the same five years.

    The 2010-2011 period shows a definite slowdown in the rate of membership growth, 5% in 2010 and 3.5% during 2011. At the end of 2011 about 66% of the membership did not own an aircraft — perhaps the highest proportion ever — so the current high cost of hiring, for possibly 66% of the members, no doubt makes a significant contribution to the circumstances prompting non-renewal of membership.

    RA-Aus aircraft register
    The number of aircraft on the register increased by 198 aircraft (6% increase) during the 12 months since 31 January 2011, 246 were added and 48 dropped off. The swing away from home-builts (now 42% of total aircraft) towards increasingly complex (and rather expensive) factory-built aircraft seems to have stabilised during the past three years. The market value of the RA-Aus flight line is currently estimated at $125 million with an average unit value around $36 500.
    Total on register 3414 3216 2955 2912   Category
    prefix Number & % of total
    at 31 January 2012 Number & % of total
    at 31 January 2011 Number & % of total
    at December 2009 % of total at
    December 2007 % of total at
    June 2006 10- 226 – 7% 234 – 7% 250 – 8% 12% 13% 19- 1092 – 32% 1024 – 32% 926 – 31% 32% 35% 28- 103 – 3% 104 – 3% 104 – 3.5% 4% 5% Home-built 1421 – 42% 1362 – 42% 1280 – 43% 48% 53%             32- 501 – 14.5% 458 – 14% 433 – 15% 14% 12% 24- 1026 – 30% 912 – 28% 741 – 25% 18% 12% 25- 263 – 7.5% 271 – 8% 290 – 10% 11% 10% 55- 203 – 6% 213 – 7% 211 – 7% 8% 10% Factory-built 1993 – 58% 1854 – 58% 1675 – 57% 52% 47%
    Regulatory environment
    The CASR Part 103* compliant exemption CAOs were issued in April:
    CAO 95.4 GFA gliders/motor gliders.
    CAO 95.8 HGFA hang gliders/paragliders plus powered variants.
    CAO 95.10 RA-Aus/HGFA low-momentum ultralights.
    CAO 95.12 ASRA gyroplanes.
    CAO 95.12.1 ASRA LSA gyroplanes.
    CAO 95.32 HGFA/RA-Aus weight shift controlled aeroplanes and powered parachutes.
    CAO 95.54 ABF hot-air balloons and airships.
    CAO 95.55 RA-Aus ultralight aeroplanes.

    For further information, see 'An overview of the legislative framework enabling powered recreational aviation'.

    *CASR Part 103 and Part 149 seem to have disappeared from view; however, in March 2011 the Director of Aviation Safety [CASA's chief] announced that CASA's recreational and sport aviation regulatory functions have been moved from the Standards Division to the Office of the Director of Aviation Safety, reporting to the Associate Director of Aviation Safety. Hopefully this will result in more decision making being directed toward the long overdue promulgation of CASR Part 103 'Sport and Recreational Aviation Operations' and Part 149 'Sport and Recreational Aviation Administration Organisations'.

    The long history of the proposed Part 103 and Part 149 legislation perhaps reveals a reason for the Director to now assume close oversight. The first notices of proposed rule making [NPRM] relating to Parts 103 and 149 were published 13 years ago (about two years after initial industry discussions) as NPRM 9808RP and NPRM 9805RP. These were subsequently followed, in 2000, by a set of rules drafted by the Attorney General's Department as another NPRM, which was promptly withdrawn by the then Director of CASA.

    Six years later, in December 2006, CASA published NPRM 0603OS, the current proposal relating to Part 103 followed, in July 2007, by NPRM 0704OS, the third proposal relating to Part 149.

    2012 There were three fatal accidents in the first half-year but none during the remainder, two of the accidents involved trikes. The death toll was five — two pilots and a passenger in the trikes, an instructor and a pilot-under-instruction in a Piper Sport. The 5-year moving average accident rate is now 3.6 per annum, an improvement on the moving average 12 months ago when it stood at 4.6 per annum. The reason for the decrease in the 5-year moving average is that 2007 — which was the worst year since 1986 — dropped out of the series and 2008 — which was the best year ever — remained in the 5-year series. The 4-year (2009 through 2012) average is 4.2 fatal accidents per annum, so the 2009-2012 improvement was rather small and indications for 2013 are very bad at the time of writing (28 February 2013).

    There were turbulent periods in 2012 for some associated with RA-Aus:
    A corporate audit by CASA's sport aviation office late in 2011 revealed major shortcomings in the process for acceptance of LSA aircraft. Some of the documentation required, under the Technical Manual section 7.5.1, was missing from those aircraft files sampled in the audit, leading auditors to the conclusion that some LSA aircraft could be flying without a valid Certificate of Airworthiness. The auditors raised a Safety Alert which is a request for immediate corrective action. At the end of November 2011 RA-Aus sent letters to 136 owners of LSA aircraft effectively grounding those aircraft until missing documentation was received. A number of aircraft from a few Australian manufacturers had their registration prefix changed from 24- (LSA) to 19- (Experimental) because of non-compliance with the ASTM standards. One kit aircraft type was grounded because the type was not manufactured in an ICAO contracting State. At December 2012 there were still some outstanding matters relating to non-LSA registration documentation which was also delaying a large number of renewals.
      There were significant staff losses which placed a heavy burden on the office in attempting to cope with the losses of skills and experience while having the additional work load occasioned by the urgent need to correct the problems identified by the audit. This added to the delays in processing normal registration renewals.
      Three Board members resigned before the expiry of their elected term, some quite early in their first term.  
    Growth in RA-Aus numbers
    The total ordinary membership at 2 January 2013 was 9906; a net decrease of 102 (1%) during the year. During 2011 there was a net increase of 334 or 3.5%, the corresponding membership increase in 2010 over 2009 was 5%, 2009 over 2008 was 9.5%; 2008 over 2007 was 8%. The change reported is the sum of new members enrolled less the turnover of the existing membership during the period, 2012 was the first year in which a membership decrease occurred since 1995. This is not unexpected — see the 2010 'growth in numbers' survey.

    RA-Aus aircraft register
    The number of aircraft on the register decreased slightly from 3414 at 31 January 2012 to 3368 on 2 January 2013. Though the change in itself may not be significant, it is the first year since 1993 that the number of aircraft has decreased. However it may be that there has been some erroneous statistical reporting due to the problems the staff have with registration renewals.

    Regulatory environment
    CASA will introduce their Recreational Pilot Licence 1 September 2014. This will authorise a person over 16 years of age to pilot a single-engine aircraft that has a maximum certificated take-off weight of not more than 1500 kg, by day under the visual flight rules if the aircraft is engaged in a private operation. The aircraft must be listed on the Australian civil aircraft register, not an RAAO aircraft register. The Australian private vehicle driver licence medical conditions apply. Persons on board is generally limited to one passenger plus the pilot. General aviation aircraft maintenance rules still apply of course. For more information see CASR Part 61 recreational pilot licence regulations 61.460 to 61.500, at pages 98 to 101 or the CASA RPL information brochure.

    This concludes the 'Joining sport and recreational aviation' series

    1. The Civil Aviation Act and the Regulations
    The aviation Acts
    Australian sport and recreational aviation, in common with all other forms of civil aviation, is subject to several levels of government regulations and rules. The primary legislative Acts are the Air Navigation Act 1920 which generally deals with Australia's international obligations in regard to international air transport in accordance with the 1944 Chicago Convention; and the Civil Aviation Act 1988, which latter is " ... an Act to establish a Civil Aviation Safety Authority [CASA] with functions relating to civil aviation, in particular the safety of civil aviation, and for related purposes. The main object of this Act is to establish a regulatory framework for maintaining, enhancing and promoting the safety of civil aviation, with particular emphasis on preventing aviation accidents and incidents."

    The Act provides for the appointment of a Director of Aviation Safety who is responsible for the management of CASA. Thus, the CASA has the function of conducting the safety regulation of civil air operations in Australian territory, in accordance with this Act and by means of the Regulations which CASA prepares for promulgation. The CASA is also the Australian National Airworthiness Authority [NAA].

    In the Act 'aircraft' is defined as 'any machine or craft that can derive support in the atmosphere from the reactions of the air, other than the reactions of the air against the earth's surface'. So lighter-than-air hot-air balloons are 'aircraft', hovercraft are not. Similarly 'aeroplane' means 'a power-driven heavier-than-air aircraft deriving its lift in flight chiefly from aerodynamic reactions on surfaces remaining fixed under given conditions of flight, but does not include a power-assisted sailplane'. Thus powered-parachutes are 'aeroplanes', para-gliders, sailplanes, hang-gliders and gyroplanes are not.

    Chapter 2 of the Criminal Code applies to all offences created by the Civil Aviation Act 1988 and a notable facet of the Act is that it specifies imprisonment for some specific offences related to Australian* aircraft operation. So, if charged by State or Federal police (for example) with an offence under the Act – the superior legislation – the penalty is likely to be more significant than if charged with an offence under the Regulations, where the penalties specified are generally fines. See 'Some noteworthy sections of the Civil Aviation Act 1988, the CAR 1988 and the CASR 1998'.

    *Note: AUF/RA-Aus registered aircraft were re-classified as 'Australian aircraft' by a September 2004 addition to item 3 'Interpretation' of the Act, thereby removing an anomaly where AUF/RA-Aus aircraft were legally 'neither Australian aircraft nor foreign aircraft, but were effectively treated as foreign aircraft that were allowed to operate in Australia but did not have the nationality of any ICAO contracting state', and thus, perhaps, avoiding some of the penalties prescribed in the Civil Aviation Act. Prior to the publication of the RA-Aus/AUF operations manual issue 6 in 2008, the introduction to issue 5 (2001) of the manual contained a clause stating words to the effect that 'Where a regulation explicitly specifies Australian aircraft' it does not apply to ultralights. The continued existence of this clause in the operations manual for four years following the 2004 amendment to the Act caused some confusion. One benefit of the 'nationalisation' is that recreational aircraft may not be discriminated against by operators of public aerodromes; see CAR 91.

    There are other Acts which affect sport and recreational aviation; for example, the Air Navigation (Aircraft Noise) Regulations 1984 and the Aviation Transport Security Act 2004. The latter restricts pilot access to the 'airside' area of aerodromes that have scheduled regular public transport movements, if the pilot does not have a valid Aviation Security Identification Card [ASIC].

    The role of the Civil Aviation Safety Authority
    'The primary function of the Civil Aviation Safety Authority (CASA) is to conduct the safety regulation of civil air operations in Australia and the operation of Australian aircraft overseas by means that include, amongst other things, developing, promulgating and implementing appropriate aviation safety standards and effective enforcement strategies to secure compliance with those standards, conducting comprehensive aviation industry surveillance and regular reviews of the system of civil aviation safety, and carrying out timely assessments of international safety developments. CASA also has a range of other safety-related functions, including, amongst other things, providing safety education and training programmes and aviation safety advice designed to encourage a greater acceptance by the aviation industry of its obligation to maintain high safety standards; fostering an awareness in industry management and the community generally of the importance of aviation safety and compliance with the civil aviation legislation; and promoting consultation and communication with all interested parties on aviation safety issues.'

    The CARs and CAOs
    The legislative tier below the Acts contains the wide-ranging Civil Aviation Regulations [CARs]. The CARs are the responsibility of CASA, but drafted by the Office of Legislative Drafting and Publishing, which is part of the Commonwealth Attorney-General's Department. New or amended CARs and CAOs must be tabled in the Federal Parliament – where they are subject to disallowance – and authorised by the signature of the Governor-General of Australia before they can become effective.

    The level below CARs contains the Civil Aviation Orders [CAOs] which are issued by CASA under regulation 5 of the CARs. They include information on technical standards and specifications intended to amplify the generalised regulations contained in CARs. In particular, they contain detailed mandatory operational, airworthiness and safety requirements, including design requirements, standards, specifications, technical and administrative procedures and safety instructions. Also, as demonstrated by the seven sport and recreational aviation section 95 CAOs, they provide exemptions to some provisions of the CARs.

    (CASA may also provide individual exemptions by means of miscellaneous legislative instruments. For example the students of some RA-Aus flight training facilities (e.g. at Launceston, Parafield, Cambridge and Coffs Harbour) are able to operate in controlled airspace, without having a CASA issued Pilot Licence*, through 'exemption instruments'. See the Sunshine Coast Aero Club's CASA EX40/10 'Exemption – solo flight training using ultralight aeroplanes registered with the RA-Aus at Sunshine Coast Airport'. Note the requirement for the student pilots to hold at least a CASA class 2 medical certificate.)

    *Note: in Australia the CASA issues 'Pilot Licences' upon qualification of Private, Commercial and Airline Transport pilots, whereas the recreational aviation administration organisations issue 'Pilot Certificates'; the terms are not interchangeable. CASA-issued Licences are recognised by ICAO, the Certificates issued by the recreational organisations are not. (In the USA all qualified pilots – amateur or professional – are 'certificated' not 'licensed'.)

    Over the years the CARs and CAOs have become somewhat of a mess – where they are in conflict CARs take precedence over CAOs and the Act takes precedence over the CARs. CASA believes the CARs and CAOs are ' ... overly prescriptive, ambiguous, disjointed, too reliant on exemptions, and difficult to interpret, comply with and enforce'.

    The ongoing CASA regulatory reform program
    Since 1994/1995 CASA has been in the process of reviewing and rewriting all the CAR and CAO legislation in the form of Civil Aviation Safety Regulations [CASRs]. These are being structured and formatted in Parts similar to the United States Federal Aviation Regulations [FARs]. The intention is also to harmonise the CASRs with U.S. and European standards and regulations; although the review is expected to retain, in the CASRs, 'aspects of current regulations which are considered superior to international legislation or better suited to Australian conditions'. The numeric listing of the CASR Parts within their operational clusters can be accessed from the CASA website.

    According to CASA's regulatory criteria the new CASRs are:
    focused on safety – a 'systems' approach clear, concise and unambiguous justified – necessary, cost-effective, based on risk management principles consistent with international obligations harmonised outcome-based enforceable and provide for delegations of authority to the industry – RA-Aus for example.  
    The review program was initially oversighted by a Program Advisory Panel [PAP] appointed by the government Minister. The basic ground rules that were agreed by PAP in 1996 were that no one currently operating legally will be made an outlaw; that the rewriting of procedures manuals* will be minimal; and that Australia will move to the FAR style regulatory system with as little change as possible. The PAP delivered its report in 1998.

    * For example the RA-Aus Operations and Technical Manuals comprise the RA-Aus Procedures Manual and the GFA Operational Regulations comprise their procedures manual.

    The CASA is consulting with the aviation community, via a Standards Consultative Committee, in the development of each new Part, then releasing Notices of Proposed Rule Making [NPRMs] for final comment before the regulations are sent for Parliamentary scrutiny. A Notice of Final Rule Making [NFRM] is normally issued after assessing feedback comments.

    The older CARs are known as CAR 1988 and the new CASR parts that have been, or are being, developed to replace CARs and CAOs are being released as CASR 1998 though sometimes, for expediency, they are released as revised/new CARs. Note that RA-Aus aircraft are exempt from the current CASRs provided the conditions in CAO 95.10, 95.32 and 95.55 respectively are met, but see the note under Civil Aviation Safety Regulations 1998. This situation will remain until CASR Parts 103 and 149 are promulgated.

    The content of these various Acts and Regulations can be found via the following links:
    Air Navigation Act 1920 (from Attorney-General's Department website) Civil Aviation Act 1988 (from Attorney-General's Department website) List of CAO titles (this website – current at 14 January 2005 [PDF file]) Listing of the CAR 1988 Regulation titles (this website – within Division and Part current at 15 January 2005) CAR 1988 Regulations (from Attorney-General's Department website) CASR 1998 Regulations (from Attorney-General's Department website) Airspace [management] Regulations 2007 (from Attorney-General's Department website) Note: the Acts retain the initial year of promulgation in their titles. The current revision of the Air Navigation Act 1920 bears no resemblance to the first version.

    CASR structure
    Just to make your day, here is an extract from the CASA guide "How to use the Civil Aviation Safety Regulations 1998" – perhaps demonstrating the formulation of the new 'clear, concise and unambigous' CASRs.

    ' ... note that 'the Regulations' contains many 'regulations' within it. In other words, Regulations means the whole statutory document; a regulation is a particular kind of part of it. The Regulations are divided into Parts, each Part dealing with a particular topic. A Part may be divided into Subparts, and a Subpart into Divisions. Divisions are divided into regulations, but a Part or Subpart can also be divided directly into regulations (that is, a Part need not have Subparts, and a Subpart need not have Divisions). An individual regulation may be divided into subregulations, a subregulation into paragraphs and a paragraph into subparagraphs. A regulation that is not divided into subregulations can be directly divided into paragraphs.'

    That quite clear?

    Supplementary documents – CAAPs and ACs
    There are two similar series of CASA documents which supplement the CARs, CAOs and CASRs.

    The Civil Aviation Advisory Publications [CAAPs] relate to the CARs only. They 'provide guidance and information in a designated subject area, or show a method acceptable to an authorised person or CASA for complying with a related regulation. The CAAPs should always be read in conjunction with the referenced regulations.' The CAAPs are in three sections – operational, airworthiness and aerodrome – and are supposed to be written in simple language.

    For examples see CAAP 166-1 'Operations in the vicinity of non-controlled aerodromes' and CAAP 166-2 'Pilots responsibility in collision avoidance in the vicinity of non-controlled aerodromes using 'see and avoid'.

    Advisory Circulars [ACs] support the CASRs only. They are intended 'to provide recommendations and guidance to illustrate a means, but not necessarily the only means, of complying with the Regulations; or to explain certain regulatory requirements by providing interpretive and explanatory material.' For an example see AC 21-42 'Certification requirements for a Light Sport Aircraft manufacturer'.

    Note that CAAPs and ACs do not define 'standard operating procedures'. They may suggest what appears to be a de facto standard but it is purely advisory, not compulsory.

    2. The recreational aviation administration organisations and the sport aviation bodies

    Recreational aviation administration organisation functions
    Recreational aviation administration organisations [RAAOs] are 'not-for-profit' associations of like-minded individuals that administer a particular sector of sport and recreational aviation (via a delegation from the Civil Aviation Safety Authority) for the benefit of Australian sport and recreational aviation in general and their members in particular. The five existing flight training RAAOs are:
    Australian Ballooning Federation Ltd [ABF] administers manned balloons and hot-air airships Australian Sports Rotorcraft Association [ASRA] administers gyroplanes and gyrogliders Gliding Federation of Australia [GFA] administers sailplanes and power-assisted variants Hang-gliding Federation of Australia [HGFA] administers hang-gliders, paragliders and power-assisted variants plus trikes. Recreational Aviation Australia Inc [RA-Aus] administers low momentum ultralight aeroplanes, single-engine very light aeroplanes, trikes and powered parachutes. ABF, GFA, HGFA, RA-Aus and the Australian Parachute Federation make up the five sport aviation bodies identified in Civil Aviation Regulation 2.

    As stated in NPRM 0704OS the regulatory authorisations involved may be:
    acceptance of a factory-built or home-built/kit-built aircraft type into their jurisdiction issue of the certificate of registration required for aircraft over 70 kg empty weight issue of airworthiness certificates (where applicable) issue of pilot qualifications issue of maintainer qualifications approval of associated flying training and maintenance training facilities surveillance activities of members of the organisations enforcement action where members are in breach of the regulations.
    CASA oversight of the RAAOs
    The arrangement with CASA is that the RAAOs are responsible for the day-to-day enforcement of standards and operational rules in accordance with the individual RAAO's CASA-approved rules and procedures manuals. Such rules and procedures are designed to meet CASA's required safety outcomes for the 27 000 RAAO members. CASA oversights the RAAOs via their sport aviation office, the Self-administering Sport Aviation Organisations Section, which is part of the Office of the Director of Aviation Safety. That oversight includes creation and monitoring of systems for the enhancement of RAAO governance and of safety management effectiveness. The organisations operate under an annual deed of agreement [i.e. a contract] with the CASA for the self-administration of their sector. (RA-Aus members can view their current deed of agreement via the members log-in page). CASA needs to be fully confident that RAAOs have the risk treatment and governance capacity to provide the safety outcomes required.

    The Sport Aviation Self-administration Handbook 2010 provides further detail on CASA's expectations for RAAOs and their management committees in ensuring that self-administration is providing a safe environment for sport aviators and their passenger*, as well as other airspace users and people and property on the ground. Also see SMS for Aviation - a Practical Guide to Safety Management System basics and the CASA Surveillance Manual - Annex 14 RAAOs.

    *Note: an 'obvious risk' of personal harm is commonly associated with sport and recreational aviation activities, perhaps to the point that the activity may be legally considered as a 'dangerous recreational activity'. Sport and recreational aviators and the single passenger allowed, are defined by CASA as informed participants in the activity being pursued. The following are extracts from CASA NPRM 0603OS for the proposed CASR Part 103:

    Section 3.5.6 'Because people who engage in sport and recreational aviation are voluntary participants in an aviation activity, where they have indicated an understanding and acceptance of the risks of participation, CASA regulates the activity on the basis that it involves informed 'participants' rather than as 'passengers' for whom the operator is responsible'.

    Section 3.5.52 'Participants in sport and recreational aviation are regarded by the regulations as being informed persons who have given their informed consent to being involved in the activities and to voluntarily inform themselves of procedures for their own protection and safety'.

    Section 3.6.5 '... in sport and recreational aviation, risk is under the control of informed participants who are encouraged to take responsibility for the consequences of their own actions but given the responsibility to make such informed choices'.

    Sport aviation bodies
    The Civil Aviation Regulation CAR 2 defines RA-Aus, ABF, GFA, HGFA and the Australian Parachute Federation [APF] as 'sport aviation bodies'. In this context, and to most aviators, the 'sport' term probably denotes some degree of competitive achievement, being particularly relevant to GFA, HGFA and APF. Competitive achievement is not so noticeable with RA-Aus pilots; however sport aviation within RA-Aus is formulated by the RA-Aus constitution's 'Statement of Purpose' paragraph B3: '... to encourage, undertake and exercise control of competitions, sporting events, displays, tests, records and trials and to hold either alone or jointly with any other association, club, company or person, recreational aircraft meetings competitions (including international competitions), matches, exhibitions, trials and receptions and to accept, offer, give or contribute towards prizes, medals and awards in connection therewith ...'

    Before issue 6 of the RA-Aus Operations Manual was finally published in 2008, section 1.03 of the manual was a statement of the duties and responsibilities of the National Flying Coach (NFC). Duty item 1 was 'Plan and formulate flying competitions at state, national and international level'. Item 6 was 'Consult with the FAI [Fédération Aéronautique Internationale], the Australian FAI representative and member bodies to ensure that competition terms are kept up-to-date'. The NFC position was active for many years but the the last person to hold that position relinquished it around 1997/1998. Since then there has been no NFC appointment, even though the statement of duties and responsibilities for the position continued in the CASA-approved manual until 2008.

    See section 9 The civil legislation governing sport and recreational aviation administration organisations for further information.
    RAAO involvement in the legislation review program
    Since 1996 the recreational aviation administration organisations have been deeply involved in the consultations with CASA and the aviation industry on the CASR Parts that are of particular interest to recreational aviation. Those Parts are:

    • Part 21 to 35: Aircraft certification and airworthiness standards.

    • Part 43: Aircraft maintenance.

    • Part 47: Aircraft registration.

    • Part 61: Certification of pilots and instructors.

    • Part 91: General operating and flight rules (Part 103 generally replaces Part 91 for sport and recreational aviation).

    • Part 103: Sport and recreational aviation operations (see NPRM 0603OS).

    • Part 105: Parachuting operations from aircraft

    • Part 149: Recreational aviation administration organisations (see NPRM 0704OS).

    Some Parts have been implemented and Parts 103 and 149, which are of most interest to recreational aviation, are unlikely to be promulgated before 2015/2016. Parts 103 and 149 are an example of how CASA is moving its classification system (albeit very slowly) from a purely operation-based scheme to a more contemporary 'risk-oriented, activity-based' system. This should be helpful to recreational pilots as much of the legislation relevant to them will be contained within Parts 103 and 149.

    3. Aircraft Type Certification and Certificates of Airworthiness
    When is aircraft type certification and airworthiness certification necessary?
    Generally* powered aeroplanes registered with RA-Aus, HGFA and ASRA are not required to have a Certificate of Airworthiness [CoA] so they are not exposed to the same certification standards to which the manufacturers of CASA registered aircraft must comply. However, an Australian manufacturer of sport and recreational aeroplanes wishing to provide aircraft for flight training activities (or if contemplating export) must comply with the relevant Type Certification and Production Certification standards and seek CASA certification.

    *Owners of aeroplanes (or gyroplanes or gliders) in the light sport aircraft [LSA] category must hold a 'Special CoA' if the aircraft was factory-built or an 'Experimental Certificate' issued by a person authorised by CASA if home-built from a factory-supplied kit.

    The airworthiness standards for sailplanes and powered sailplanes are contained in CASR Part 22 which encloses the European airworthiness standards set out in the certification specification EASA CS-22.

    As the subject of 'certificated aircraft' or 'certified engines' continually crops up, the following may be of interest. Be aware that, at first glance, some of the terms are very similar, but they may have quite different regulatory meanings – and are often misused or misquoted.

    (The certification and airworthiness requirements for aircraft and parts are contained in CASR Part 21.)

    The Type Certificate
    Type Certification is the assessment by the national airworthiness authority [NAA] of an aircraft type and model (or engine or propeller) for compliance with an international airworthiness design standard (that is recognised by the International Civil Aviation Organization) for a particular airworthiness category – normal, utility, acrobatic and primary are some of those categories. Type certification design standards (e.g. FAR Part 23 and CAO 101.55) are a set of commonsense rules, graded according to the activity for which the aircraft is designed, that have evolved over the past 100 years or so, which – while not providing absolute safety in all conditions – do provide an airworthy and reasonably stable and controllable aircraft; providing it is operated within the specified flight envelope and is maintained according to a maintenance schedule defined by the manufacturer. Under those conditions, for an FAR Part 23 aircraft, there is an expectation of not more than one serious accident due to structural failure per million type flight hours. The Type Certificate [TC] is issued by the NAA (initially in the country of origin) to the manufacturer (the 'TC holder'). The TC for earlier aircraft may be referred to as the Type Approval Certificate or the Certificate of Type Approval.

    Aircraft registered under CAO 95.55 para 1.2 (f) [RA-Aus registration 24-xxxx] are commercially-built in Australia, or by a manufacturer in another ICAO member nation. The manufacturer must hold a Type Certificate, a Certificate of Type Approval or an equivalent document issued by a NAA; such aircraft may be used for flight training. The manufacturer must also hold a Production Certificate for the aircraft.

    Note: manufacturers of light sport aircraft don't hold a type certificate issued by any NAA or need to hold a production certificate. Instead the manufacturer of the LSA issues a Statement of Compliance document – with each aircraft delivered – certifying that this aircraft complies with the approved LSA standards and that the regulatory criteria for a 'qualified manufacturer' has been met. The compliance statement forms the basis for subsequent issue of a Special Certificate of Airworthiness by CASA. Not having to go through the type certification and production certfication processes is one of the benefits of the LSA concept to manufacturers.

    A Type Certificate Data Sheet [TCDS] is included with the TC. An Australian manufacturer of recreational aircraft who wishes to export would probably need to hold a TC for the product to be accepted by a foreign NAA. For an example of a TC and TCDS issued in the primary category see Airborne's TC and TCDS for their Edge XT/Streak 3 wing aircraft.

    The terms certified or type certified design are in common use and may apply to an aircraft, an engine or a propeller for which the particular manufacturer holds a TC. Generally, NAAs do not themselves 'certify' or 'guarantee' anything, they issue 'certificates' to the manufacturer after accepting that the manufacturer has proven their product will meet the authority's defined standard/s.

    For commercially manufactured aeroplanes the design (and the prototype aircraft) must be type certificated and the manufacturer issued with a TC before any individual production series aircraft can be issued with a CoA – for its intended operating category – by any NAA; e.g. the FAA in the USA, the EASA in the European Union and the CASA in Australia.

    Type Acceptance Certificate for imported aircraft
    In Australia (to enable the issue of an Australian CoA and thus 'VH' registration) CASA must issue a Type Acceptance Certificate [TAC] for an imported aircraft type and model whose manufacturer holds a TC issued by one of the 'recognised' NAAs.

    The RAAOs do not approve factory-built aircraft; however, RA-Aus (for example) is authorised to issue an RA-Aus Type Acceptance Certificate signifying only that a particular factory-built aircraft type and model is accepted for registration by RA-Aus under CAO 95.55 para xx on the basis of a Type Certificate, Type Approval Certificate or other equivalent document issued by a NAA.

    Production Certificate
    Production Certification is carried out by a NAA to assess a company's manufacturing and quality assurance systems and procedures. If satisfied that all aircraft produced will meet the quality standards established by the Type Certificate the authority will issue a Production Certificate. If the TC holder does not also hold a Production Certificate then every aircraft produced must be inspected by a representative of the NAA before its CoA can be issued.

    Certificate of Airworthiness
    The standard Certificate of Airworthiness [CoA] for an individual factory-built aircraft is issued on the basis of evidence that the individual aircraft complies with the Type Certificate and that it has been constructed and assembled satisfactorily by the holder of a Production Certificate for manufacturing and given an individual constructor's serial number. The various airworthiness categories and designations in which Australian CoAs may be issued are described in detail in Advisory Circular AC 21.1 'Aircraft Airworthiness Certification Categories and Designations Explained'. CoAs are not required for ASRA, RA-Aus and HGFA registration except for the aircraft in the light sport aircraft [LSA] category, but see 'A few pointers from the RA-Aus Technical Manager concerning LSA registration.'

    Certificates of Approval (of company operations)
    After receiving an audit request CASA may, under CAR 30, subsequently issue a Certificate of Approval to a person or company engaged in any stage of design, documentation, manufacture, distribution or maintenance of aircraft, aircraft components or aircraft materials. That certificate indicates that CASA is currently happy with the quality assurance aspects of the specified activities of the company's operations and recognises that the holder has met the civil aviation regulatory requirements for the granting of their Certificate. Note that it is not a Certificate of Type Approval nor is it a Production Certificate. An approval holder might advertise themselves or their services (but not their wares) as "CASA approved".

    RAAO acceptance of aircraft for registration
    RA-Aus acceptance processes, for example, apply to commercially manufactured aircraft kits available to RA-Aus amateur builders, to ensure that the kits comply with the 51% 'major portion rule'. See the Technical Manual section 3.3.1 'Amateur built aircraft registered as ultralight aircraft'. RA-Aus acceptances also apply to commercially available aircraft plans.

    For the design and airworthiness certification Orders for recreational aviation see the design and airworthiness certification Orders for powered recreational aeroplanes below.

    CASA approval of sport and recreational aircraft engines
    Various requirements are applied to the flight of recreational aeroplanes in controlled airspace. One such requirement relates to the engine which must have either a Type Certificate, a Type Approval Certificate or is of a type that has been approved by the CASA as being appropriate for use in controlled airspace. The latter is usually applied to non-Type Certificated engines that display a proven history of reliability; it is the most common Australian means of meeting the engine approval requirement for non-certified engines. CAO 101.55 section 6.1 is referred to in the CAO 95-series exemption orders.

    4. Exemption aircraft
    'Exemption' aircraft are those specified in the CAO 95-series, and are not classified as categories in the airworthiness sense. Thus, excluding sailplanes, RAAO registered aircraft may not be 'type certificated' or reflected as a category in either 'standard' or 'special' or 'experimental' CoA, except for those in the LSA classification. However, depending on their design standards and modes of construction, certain sport and recreational aircraft could also be registered on the National aircraft register (i.e. 'VH' registration with CASA) and issued with a special CoA or an experimental certificate in the 'amateur-built aircraft acceptance' (ABAA), 'amateur-built' or 'kit-built (experimental)', 'primary' or 'intermediate' categories.

    Seven CAOs provide sport and recreational aviation with the necessary operating exemptions from some sections (listed within each CAO) of the Regulations but, of course, all other current CARs, CASRs and CAOs (plus the Civil Aviation Act itself) could apply to RAAO registered aircraft and RAAO certificated pilots. It is expected that with the implementation of CASR Part 103 and Part 149 the seven CAOs will be rescinded but their intent will be incorporated partly within the two CASR parts but chiefly as rules/requirements/procedures within the RAAOs Operations/Technical Manuals. The content of the seven CAOs has been made as uniform as possible.

    Four of the exemption CAOs are CAO 95.4 for GFA sailplanes and CAO 95.8 for HGFA hang-gliders and paragliders (including powered variants). CAO 95.12 is for ASRA gyroplanes with empty weight not more than 250 kg plus CAO 95.12.1 for LSA gyroplanes of maximum gross weight not more than 600 kg. CAO 95.54 is for ABF hot-air balloons and hot-air airships.

    Also an exemption order (CAO 95.14) exists for parasails and gyrogliders, but these vehicle- or boat-towed aircraft are restricted to operations below 300 feet above surface level.

    The remaining three CAOs are applicable to RA-Aus and HGFA aeroplanes and together form the most complex of the exemption orders. These CAOs sparked and sustained the outstanding growth in Australian powered recreational aviation; they are CAO 95.10, CAO 95.32 and CAO 95.55.

    5. The exemption Orders specific to 'aeroplanes' – CAOs 95.10, 95.32 and 95.55
    In the Australian regulatory context the term 'aeroplane' means a power-driven, heavier-than-air aircraft deriving its lift in flight chiefly from aerodynamic reactions on surfaces remaining fixed under given conditions of flight. Powered parachutes are classified as aeroplanes (their ram-air wings remain fixed in normal operations) but not gyroplanes, power-assisted hang-gliders or power-assisted sailplanes – the latter are still classified as 'sailplanes or gliders' (CAR 2). So, in this document, the term 'recreational aeroplanes' refers only to aeroplanes registered with RA-Aus and the HGFA. Powered hang-gliders or powered para-gliders registered with the HGFA are not included.

    Operating airspace allowed, pilot qualifications and equipment required
    The Class G and Class E airspace over the Australian continent, below 10 000 feet above mean sea level in day VMC conditions, is available to recreational aviation – around 20 million cubic kilometres of airspace to explore. However flight over cities and towns is restricted.
      Carriage and use of a VHF transceiver is mandatory for operations above 5000 feet; in the vicinity of non-towered aerodromes and in controlled airspace. A Mode A/C or S transponder is also necessary in some control zones and in Class E. Please read 'Class E airspace' in the navigation tutorial.
      A two-place aircraft undertaking a flight more distant than 50 nautical miles from its departure point must carry an approved ELT. Please read the information on distress beacons contained in the 'Safety and emergency communication procedures' tutorial.
      Class C and D controlled airspace is not available to recreational pilots who do not also hold a valid pilot licence that allows flight inside such airspace, a current aeroplane flight review and at least a class 2 medical certificate; except if there a legal exemption instrument in place for a particular control zone that facilitates access by the student pilot certificate holders of a particular RA-Aus resident flight school. Those student pilots must also have a valid class 2 medical certificate. For flight in Class A airspace, the pilot of a recreational aircraft must seek and receive written permission from the Civil Aviation Safety Authority for the flight.

    For operations in controlled airspace the aeroplane must be: certificated to the design standards of CAO 101.55 or is entitled to a type certificate for an aircraft in the primary category by meeting the criteria specified in CASR 21.024 paragraph (1) (a) or is entitled to a type certificate for an aircraft in the intermediate category by meeting the criteria specified in CASR 21.026 paragraph (1) (a) or is entitled to a type certificate for an aircraft in the Light Sport Aircraft category by meeting the criteria specified in CASR 21.186 or approved under regulation CAR 262AP 'Experimental aircraft - operating limitations' in relation to flights over closely-settled areas. See 'Flight over the built-up area of a city or town' The engine must be of a kind to which paragraph 6.1 of CAO 101.55 applies, or that CASA has approved as being suitable for use in a recreational aircraft in controlled airspace and is not subject to any conditions that would prevent the flight. For more detailed information on the requirements for recreational aircraft operations in controlled airspace see CAO 95.55 paragraph 7.3, CAO 95.32 paragraph 7.3, CAO 95.12 paragraph 6.3, CAO 95.12.1 paragraph 7.4 or CAO 95.10 paragraph 6.4. For information on recreational aircraft clearances for operations in restricted areas, see 'restricted and danger areas'.  
    All recreational powered aircraft wishing to operate at or above 10 000 feet amsl in Class G or Class E airspace, must apply to CASA and receive written CASA permission for each planned flight. The aircraft must be equipped with an operating Mode A/C or S transponder and the Australian Civil Aviation Order 20.4 sub-section 6 specifies use of supplemental oxygen systems.  
    Flight over closely-settled areas
    Note: while CAR 262AP uses the term 'built-up area of a city or town', the subordinate 95 series CAOs use the term 'closely-settled area' meaning an 'area in which, because of man-made obstructions such as buildings and vehicles, and the characteristics of the aeroplane; the aeroplane could not be landed without endangering the safety of persons unconnected with the aeroplane or damaging property in the area'.
    Flight over closely-settled areas is prohibited to all CAO 95.10 aircraft.
      CAO 95.55 subparagraph 1.2 (a), (e) and (h) aircraft [i.e. those with 28-nnnn and 19-nnnn registration] plus CAO 95.32 paragraph 1.3 and 1.4 aircraft [i.e. E-LSA and 51% owner-built powered parachutes and trikes] are – for the purpose of flight over closely-settled areas – all regarded as 'experimental' and may not operate over such areas, unless holding a written authorisation to do so.

    CAR 262AP deals with operating limitations for experimental aircraft; subregulations 4 and 5 state:
    (4) A person must not operate an experimental aircraft over the built-up area of a city or town unless authorised to do so under subregulation (5).
    (5) CASA or an authorised person may authorise a particular aircraft to be operated over the built-up area of a city or town subject to the conditions and limitations CASA or the authorised person considers necessary for the safety of other airspace users and persons on the ground or water.

    The penalty for non-compliance is 50 penalty units [about $6000].

    For RA-Aus registered aircraft the Technical Manager is the authorised person who may issue the written approval. The period of validity for an authorisation is variable, the approval will expire when or if cancelled by CASA or the authorised person.

    An aircraft must not be flown over a closely-settled area at a height from which it cannot glide clear of the closely-settled area to a suitable landing area and the minimum height is 1 000 feet above ground level. 'Suitable landing area' means an area in which an aeroplane can be landed without endangering the safety, or damaging the property, of persons unconnected with the aeroplane.  
    Aeroplane take-off weight limits
    All the sport and recreational aviation exemption orders specify a limiting take-off weight (in a few cases, a limiting empty weight) for each aircraft class defined in the CAO. The take-off weight defined is the total weight of the aeroplane when it begins to taxi before taking off. 'Gross weight' and 'all-up weight' have the same meaning as 'total weight'.

    The maximum allowed take-off weight [MTOW] has a number of connotations.
    The first is the class regulatory limit set by the CASA for recreational aeroplane operations and currently specified in the exemption orders; it is generally 600 kg but it could be less – and up to 850 kg for sailplanes. Those CAOs allow an individual aeroplane to be registered, within a class defined by one particular CAO sub-category, for operation not above a specified take-off weight. In addition there may be a maximum stalling speed in the landing configuration or a maximum allowed wing loading specified in those orders.
      The second connotation is the structural design weight limit which is the maximum all-up take-off weight permitted by the aircraft designer, for structural safety and/or aircraft stability and control reasons; usually accompanied by a limitation of the fore and aft positions of the centre of gravity.

    An aeroplane which, by design, is capable of operating safely at a greater weight than the class regulatory limit may still be able to be registered with an RAAO, provided the pilot does not operate the aeroplane at an all-up weight that exceeds the class regulatory limit – including the maximum stall speed – defined by the relevant CAO. Many small, light, composite aircraft are imported from Europe where the European Union certification standard for very light aircraft is CS-VLA (formerly JAR-VLA) with a class regulatory limit of 750 kg. These modern technology aircraft have a comparatively low empty weight and potentially high fuel capacity, so it is quite feasible to operate them as two-place 600 kg aeroplanes – provided the combined weight of the occupants is not excessive.
      There are other older design, two-place, light aircraft where the structural design weight limit is significantly higher than the class regulatory limit. It may be that an RAAO might accept such an aeroplane after negotiation, but these are required to carry a cockpit placard stating that the MTOW does not exceed 600 kg – or whatever the class regulatory limit might be. Because such aircraft have a comparatively high empty weight they must be operated as a single-seat aircraft so permanent removal of the passenger seat, seatbelt, passenger-side controls etc would be required to ensure operation only as a single-place aeroplane.
      In the type approval process, an aircraft might be assessed by a NAA to determine that the structural design weight limit is considered safe. Subsequently, the third connotation – a maximum total weight authorised [MTWA] – may apply. The MTWA may be less than the structural design weight limit and may be less than the class regulatory limit.
      The situation is further complicated when overseas factory-built aircraft are imported into Australia for registration with an RAAO. An example is the European countries who certify their aircraft to an European ultralight standard of 450 kg or 472.5 kg (the 22.5 kg is the addition for a parachute recovery system). If imported into Australia and registered with an RAAO, that organisation has no choice but to limit the aircraft to 450 kg/472.5 kg MTOW even though the class regulatory limit might be 600 kg. However, if the manufacturer certifies them to another standard at a greater weight – providing that certification is accepted by a certifying body in a country that is an ICAO signatory – then an Australian RAAO can accept that higher weight, but only up to our regulatory cut-off point. Australia is an ICAO signatory and the CASA is a certifying body.
      Where an aircraft type does not quite fit the parameters outlined above an RAAO can make a decision regarding the allowable MTOW.  
    From a flight operation and safety viewpoint, the most important MTOW is the structural design weight limit, which may be less than, or greater than, the MTOW allowed under the relevant CAO or by the RAAO. The distribution of that weight – the aircraft balance – is equally important.

    The structural design weight limit is related to the category of operation and the flight envelope. In the 'normal' category, applicable to all ultralights, the structure, particularly the wing, is required to cope with minimum structural limit load factors of +3.8g to –1.5g. Thus, the wing of a non-aerobatic aircraft with a certificated MTOW of 600 kg is required to cater for a design limit load of 600 × 3.8 = 2280 kg plus the 50% safety factor for the ultimate load = 3420 kg. The design limit loads in the LSA category are +4g and –2g.

    No matter which CAO class regulatory limit recreational aircraft are generically permitted to operate at, no aircraft may fly legally above the RAAO accepted MTOW for that particular aircraft type, which may not be as much as the class regulatory limit or the structural design weight limit.

    Civil Aviation Order 95.10
    Civil Aviation Order 95.10 is an instrument which legalises the flight of a single-place low-momentum* ultralight aeroplane registered with RA-Aus or HGFA (if weight-shift controlled), without it (or any part of it) being certificated to any airworthiness standard for design, materials or construction. There is no restriction on the flight control system (i.e. three-axis, weight-shift or hybrid), the number of engines, the type of propulsion, the type of propeller system (or even the existence of such – it could be a pulse jet) or type of undercarriage; i.e. it could be retractable. Of course the 300 kg MTOW and maximum 30 kg/m² wing loading tends to limit choices. There is an additional weight allowance of 20 kg for a parachute recovery system and/or 35 kg if equipped to land on water – a four-engine amphibian has been flown.

    *Note: a 'low momentum ultralight aeroplane' is not yet defined in the regulations except that it has a low maximum take-off weight and a low wing loading but it may also indicate an ultralight aeroplane which has a maximum cruising speed no greater than 55 knots, which would accord with Part 103 of the United States ultralight aviation regulations. On the other hand momentum equals mass × velocity so 'low momentum' does not necessarily infer low maximum speed.

    The legislation was initially promulgated in 1976 as ANO 95.10 by a forward-thinking authority, to allow the 'minimum aircraft' movement to build their own aircraft from any commercially available materials. It also provided an exemption from the then existing Air Navigation Orders – provided the aeroplane was not flown above 300 feet agl, or within 300 metres of a sealed road or within 5 km of an airport; the intent being that the only person put at risk was the pilot.

    The current version (June, 2014) of CAO 95.10 can be viewed in pdf format.

    The operating restrictions in 95.10 were loosened in 1983 – with the inception of the AUF/RA-Aus – and there have been small, gradual gains since. Now 95.10 aircraft, with current RA-Aus registration documents (or Hang Gliding Federation of Australia registration if weight -shift controlled) may be flown by an unlicenced, but RA-Aus/HGFA certificated pilot, up to 10 000 feet amsl, and not over closely-settled areas. In Australia, CAO 95.10 put in place the platform on which low-cost, minimum aircraft aviation was built; particularly for the truly innovative amateur designer/builders. See 'Benchmark events in Australian powered recreational aviation history'.

    A CAO 95.10 ultralight aeroplane may be:
    partly manufactured by a commercial manufacturer in kit form (that must be RA-Aus/HGFA approved) and then completed by a private builder (i.e. kit-built) or built from purchased plans or even designed by the private builder (i.e.scratchbuilt). If a scratchbuilt aeroplane is built in accordance with commercially-supplied drawings and/or a data package, these documents must be RA-Aus/HGFA approved and if designed by its builder(s) the aeroplane need not comply with any promulgated design standard; though it would be a most imprudent designer/builder who did not follow some recognised standard route in the development of his/her aircraft. The current CAO 95.10 does not allow for an aeroplane to be completely built by a commercial manufacturer (i.e. factory-built) – as was available prior to 1990.

    CAO 95.10 continues to provide the only means by which an enthusiastic private (i.e. not commercial) builder or small group (maximum of four private builders – who are not required to have any aeronautical or engineering experience) can now design and build a low-cost single-place aeroplane, whether the design is conventional or unconventional, with no restrictions, except that:
    the class regulatory take-off weight must not exceed 300 kg with an additional allowance of 20 kg if equipped with a parachute recovery system and/or 35 kg if equipped to land on water. The designer/builder/airworthiness certifier may limit the take-off weight to a value lower than 300 kg, in which case the maximum legal take-off weight [MTOW] will be the lower of the class regulatory value and the designer/builder/airworthiness certifier's MTOW. wing loading must not exceed 30 kg/m² (about 6 lb/ft²) at maximum all-up weight. a placard must be placed in the cockpit warning that neither the CASA nor RA-Aus/HGFA guarantee the airworthiness of the aeroplane and pilots operate it at their own risk. If kit-built from an approved kit supplied by a commercial entity there is no stipulation regarding the minimum extent of fabrication or assembly input to be provided by the builder/s. See the RA-Aus Technical Manual section 3.4.1 "Approval of a kit for a CAO 95.10 ultralight aircraft" and section 3.4.2 "Approval of a kit for a CAO 95.10 ultralight aircraft based on history of safe operation".

    There is no requirement that the aeroplane be built under supervision and the design may be modified as the builder sees fit. The RA-Aus registration marking is 10-xxxx.

    Unfortunately the interest in scratchbuilding has declined markedly and very few CAO 95.10 new builds are being registered. In 1994 there were about 550 CAO 95.10 aircraft representing 47% of the RA-Aus register. In January 2012 there were 226 such aeroplanes remaining, less than 7% of the register. The number of 95.10 aircraft has decreased by more than 100 machines during the past five years.

    The photograph shows an aircraft from designer/builder David Rowe – his UFO or "Useless Flying Object". This aircraft is a consequence of David's curiosity about the behaviour of round wings and illustrates the educational and true experimental essence of 95.10 and its importance to the ultralight movement. It also emphasises that, in 95.10, the designer/builder is likely to be the test pilot.

    Civil Aviation Order 95.32
    CAO 95.32 is a very popular operational standard providing exemption from some provisions of the Civil Aviation Regulations for factory-built, kit-built and amateur-built single-place or two-place weight-shift controlled aeroplanes ('trikes' or 'microlights') and powered parachutes. CAO 95.32 aircraft comprise 15% of the RA-Aus aircraft register; more than 200 (or 40%) of these aircraft are powered parachutes from Aerochute Industries.

    The current version (April, 2011) of CAO 95.32 can be viewed in pdf format.

    The aircraft must be registered with RA-Aus or the HGFA (trikes only). Trikes have a regulatory take-off weight limitation of 600 kg (650 kg if equipped to land on water), there is no weight allowance for a parachute recovery system and the stall speed must not exceed 45 knots CAS. Powered 'chutes have a weight limitation of 600 kg. Unlike CAO 95.10 the CAO 95.32 does not provide an additional weight allowance for a parachute recovery system.

    Paragraph 1.1 of the CAO refers to a factory-built or kit-built aeroplane where the manufacturer of the aeroplane, or kit, must hold some form of Certificate of Approval or Production Certificate or airworthiness certification acceptable to CASA; or complies with the British airworthiness requirement BCAR-S for small light aeroplanes; or there is similar approval or acceptance from a NAA – whether the aircraft or kit is Australian-made or imported. (32-xxxx RA-Aus registration marking.)

    Paragraphs 1.2 and 1.3 cover aeroplanes in the light sport aircraft category. If factory-built the aeroplane must be manufactured by a qualified manufacturer (as defined in CASR 21.172. If kit-built CASR 21.191 sub-paragraphs (j) or (k) apply, but there is no minimum amount of the fabrication and assembly labour to be done by the owner. The aircraft owner must hold a current 'special certificate of airworthiness' if factory-built or a current 'experimental certificate of airworthiness' if kit-built. For more information see the LSA category in CAO 95.55 and 95.32 below.

    Paragraph 1.4 refers to amateur-built aeroplanes where the major portion (51%+) of the fabrication and assembly work is done by the owner, the balance being supplied by a commercial manufacturer, usually in kit form. For further information see the same category in CAO 95.55 para 1.2 (e).

    Factory built certified weight-shift aeroplanes and powered parachutes are allocated the '32' registration mark prefix, amateur built weight-shift aeroplanes and powered parachutes are now allocated the '18' registration mark prefix while (kit-built) experimental LSA weight-shift aeroplanes are now allocated the '17' registration mark prefix.

    Civil Aviation Order 95.55
    CAO 95.55 is an operational standard which provides exemption – for certain three-axis controlled, single-engine, single-propeller, single-place or two-place ultralight aeroplanes with a Vso stall speed not greater than 45 knots CAS and with valid RA-Aus registration – from some provisions of the Civil Aviation Regulations. (Engine type; e.g. internal combustion, is not specified.) There are eight classifications within 95.55 – four 'home-built' and four 'factory-built'. Unlike CAO 95.10 the CAO 95.55 does not provide additional weight allowance for a parachute recovery system.

    The current version (April, 2011) of CAO 95.55 can be viewed in pdf format.

    The relevant paragraphs of the CAO are:

    Para 1.2 (a): the amateur-built aircraft acceptance [ABAA] category. An amateur-built aircraft is an aircraft, the major portion of which has been fabricated and assembled by a person or persons who undertook the construction project solely for their own education or recreation. The ABAA is a type approval for an amateur-built aircraft.

    The aeroplane must comply with the design standards specified in part 3 of CAO 101.28; plus MTOW not exceeding 600 kg for a landplane and 650 kg for a seaplane/amphibian. Such aircraft were registered by RA-Aus with a 28-xxxx marking.

    Para 1.2 (b): an aeroplane described in paragraph 1.1 of CAO 101.55 which limits MTOW to 450 kg, maximum power cruising speed to 100 knots CAS and Vso stall speed not exceeding 40 knots CAS. RA-Aus registration marking 28-xxxx. The RA-Aus amateur-built aircraft (see para. 1.2 (e) below) has now largely replaced the ABAA aircraft. There are less than 100 ABAA aeroplanes remaining in the RA-Aus register and new registrations in this classification are no longer accepted.

    Para 1.2 (c): a commercially-built aeroplane meeting the design standards of CAO 101.55. Maximum weight and Vso can be 480 kg and 42 knots CAS respectively if the product of the square of Vso (knots CAS) and the MTOW (kg) does not exceed a value of 768 000. Straight and level speed under full power is not to exceed 100 knots but may be approved with a control flutter substantiation. Maximum 2 places. Can be used for training. RA-Aus registration 55-xxxx but there have been few new registrations in recent years and now new registrations in this classification may not be accepted.

    Para 1.2 (d): covers the two-place ultralights commercially-built in a CASA approved factory to a CASA certificated design and registered under the old CAO 95.25. The latter was originally issued in 1985 – as both an operational and a quasi-design standard – when, because of a high accident rate in 95.10 aircraft, the need for two-place training aircraft was determined which facilitated the production of aircraft such as the Thruster and Drifter. The specified airworthiness conditions included rather basic performance and structural tests and a demonstrated history of safe operation. CAO 95.25 also introduced the CASA certificated design for factory-built single-seaters with a 340 kg MTOW such as the Sapphire and Vampire.

    The CAO 95.25 was an emergency document, finally cancelled in 1990, and is now superseded. The RA-Aus registration is 25-xxxx but new registrations in this classification are no longer accepted. Existing aircraft may not be modified without the approval of a CAR 35 engineer. There were various iterations of acceptable MTOWs as 95.25 was developed, the final one being 450 kg for two-place aircraft meaning that the MTOW for any particular 95.25 aeroplane is the MTOW specifically approved for that aeroplane either at the time of manufacture or as later approved under the regulations by an engineer with CAR 35 qualifications.

    Although the design specification was limited the 95.25 aircraft proved to be very successful, training most of the RA-Aus pilots; but nowadays operators need to remain vigilant in ensuring the continued airworthiness of the airframe.

    Para 1.2 (e): RA-Aus (AUF) Amateur Built Aircraft [AABA]. Introduced in 1998 and, in effect, an expansion of 95.10 allowing a heavier, but more durable, structure. (Sometimes referred to as "Experimental" but the AABA is only a sub-set of the Experimental Category.) An aeroplane where the major portion (i.e. at least 51%) of the total construction work must be the owner's construction input. The aeroplane is intended for educational or recreational purposes, plus MTOW = 600 kg or 650 kg if equipped to land on water; maximum two places. The aircraft need not be designed to an approved standard, or constructed from certified type materials, and can be of any origin but must be built in accordance with the RA-Aus Technical Manual section 3.3.1.

    Can be built from scratch (own design or purchased plans) or from a kit supplied by a manufacturer who may or may not hold a CASA Production Certificate, but the kit must also be eligible to comply with the 51% 'Major Portion Rule' under CASR Part 21. The same conditions apply in CAO 95.32 para 1.4 for weight-shift controlled aeroplanes.

    There is no requirement that the aircraft be built under supervision. A pre-cover/pre-closure inspection is highly recommended, and there must be a pre-flight final inspection, observed by RA-Aus/CASA authorised inspectors, but that final inspection does not determine airworthiness – the owner/builder must accept entire responsibility for that, and sign a document to that effect before the first flight. As with CAO 95.10 the aircraft must carry a cockpit placard warning that the aircraft is not required to comply with the safety regulations for standard aircraft and persons (passengers) fly in it at their own risk. RA-Aus registration 19-xxxx. (The same conditions apply in CAO 95.32 para 1.4 for weight-shift controlled aeroplanes.)

    The photograph shows a Jabiru where Peter Kayne, the owner/builder, modified a standard tricycle undercarriage kit to produce an experimental taildragger configuration. This was so successful that the Jabiru company produced kits for the new model. These kits would comply with the AABA category.

    Para 1.2 (f): allows the commercial manufacture of a heavier aircraft than allowed under CAO 95.25 and CAO 95.55 para 1.2 (c). The aircraft is commercially-built in Australia or overseas for sale by the holder of a Type Certificate, Type Acceptance Certificate or a Certificate of Type Approval or an equivalent document issued by a National Airworthiness Authority – CASA for aircraft manufactured in Australia. The manufacturer must also hold a Production Certificate for the aircraft. RA-Aus registration 24-xxxx. Such aircraft may meet the RA-Aus registration requirement that only certified and properly approved factory-built aircraft should be used for flight training.

    The MTOW is 600 kg, or 650 kg if equipped to land on water, and the aircraft must have a minimum useful payload. This minimum payload in kg is calculated with a formula which allows 80 kg for each seating place plus 23% of the engine rated power (in units of brake horse-power) for fuel. Thus the minimum payload for a two-place 100 hp aircraft would be 80 + 80 + (0.23 X 100) = 183 kg or, deducting that from the 600 kg MTOW, the aircraft empty weight (including engine oil and unusable fuel) must be less than 417 kg.

    Note: CAO 95.55 paragraph 1.3 provides two different algorithms, one for rated power in brake horse-power units and weight in pounds, the other for power in kilowatts and weight in kilograms. The horse-power/kilogram algorithm above uses the more common terms and provides the same results.

    LSA categories in CAO 95.55 and 95.32: Light sport aircraft [LSA] is a certification category of general aviation and sport and recreational aircraft which became legal for RAAOs, in January 2006, by amendments to the exemption CAOs. LSA as a category did not replace any previously existing category nor was it intended for existing aircraft already operating under a different airworthiness category. It is a single-propeller, two-place aircraft with MTOW not exceeding 600 kg [650 kg as a seaplane], 45 knot Vso CAS. It may be factory-built or it can be a kit-built aircraft of the same make and model as the factory-built aircraft; the LSA category also exists for trikes, powered 'chutes, gyroplanes and sailplanes.
    CAO 95.55 para 1.2 (g) and CAO 95.32 para 1.2 refer to a ready-to-fly aircraft manufactured by a qualified manufacturer (as defined in CASR 21.172. The aircraft owner holds a special certificate of airworthiness for the aeroplane. RA-Aus registration is 24-xxxx for 3-axis aeroplanes (but the November 2014 issue of the RA-Aus Operations Manual introduced the 23-xxxx prefix for new registrations) and 32-xxxx for weight-shift controlled aircraft.
      CAO 95.55 para 1.2 (h) and CAO 95.32 para 1.3 refer to a a kit-built version of the same make and model as the ready-to-fly LSA aircraft. CASR 21.191 sub-paragraphs (j) or (k) apply. The 51% 'Major Portion Rule' does not apply to LSA; i.e. the manufacturer can supply a much more advanced kit than allowable under the 51% owner input Amateur Built category however, the kit-built aircraft must be inspected and the aircraft owner issued with an Experimental Certificate by a CASA 'authorised person' before it can be registered with RA-Aus as 17-xxxx for both 3-axis and weight-shift aircraft.

    Read the Synopsis: the Light Sport Aircraft category particularly the notes from RA-Aus Technical Manager. Also see the CASA advisory circulars AC 21-42 LSA Manufacturer's Requirements (but note the reference to the 'PICA 26' standard in Appendix 1 para 3.1 is not valid) and AC 21-41 LSA Certificate of Airworthiness – both pdf documents.  
    The foregoing CAO 95.55 material is summarised below:
    CAO 95.55
    para. MTOW Vso Construction Airworthiness
    standards reference. Other requirements RA-Aus registration
    mark prefix 1.2 (a)* 600/650 45 Own design,
    drawing or kit 101.28 section 3 nil 28* 1.2 (b)* 450 40 Own design,
    drawing or kit 101.55 para 1 nil 28* 1.2 (c)* 480 42 Factory-built 101.55 para 1.2
    and design standards Vno=100 55* 1.2 (d)* 450 ? Factory-built 95.25 nil 25* 1.2 (e) 600/650 45 Own design,
    drawing or kit Tech. manual 3.3.1 51% major portion
    rule applies to kits
    Pre-flight final inspection 19 1.2 (f) 600/650 45 Factory-built 101.55 Min. payload 24 1.2 (g) 600/650 45 Factory-built S-LSA standards nil 24 & 23 1.2 (h) 600/650 45 Home-built
    from factory kit X-LSA standards 51% major portion
    rule not applicable 17
    *New registrations under CAO 95.55 para's 1.2 (a), 1.2 (b), 1.2 (c) and 1.2 (d) [i.e registration mark prefixes 25, 28 and 55] are no longer available.

    6. The exempted Regulations
    If (and only if) the conditions set out in CAOs 95.10, 95.32 or 95.55 are complied with in relation to an aeroplane to which each CAO applies, the aeroplane/pilot is exempt from compliance with the following Parts of the Regulations and a few individual Regulations. In most cases the exemption from the Part or an individual Regulation is replaced to some extent by rules or requirements stated in the CAO or in RAAO Operations and Technical Manuals. For example the exemption from CAR 157 'Low flying' is offset by CAO 95.55 sections 7.1 (b) (h) (i), 8.1 and 8.2 plus RA-Aus operations manual section 2.01 para 10.

    Some of the exemptions will not apply to aircraft operating in Class A, B, C and D airspace and flown by a CASA-licensed pilot, particularly those exemptions associated with pilot qualifications.

    Failure to comply with the rules/requirements of the operations and technical manuals renders the exemptions null and void thus the exemption Regulations below, and associated penalties, become immediately applicable and may be severe. Read the opening paragraphs of the document Some noteworthy sections of the Civil Aviation Act 1988, the CAR 1988 and the CASR 1998.

    Some of the CAR 1988 Parts/Regulations mentioned below may have been replaced by CASRs but the CAO may not yet be changed to reflect this.

    Exemptions common to 95.10, 95.32 and 95.55
    Part 4A. Maintenance Part 4B. Defect reporting Part 4C. Flight manuals Part 4D. Removal of data plates and registration identification plate Part 5. Qualifications of flight crew Subregulations 83 (1) (2) and (3). Aircraft radiotelephone operator certificate of proficiency in respect of VHF equipment only. CASA HF radiotelephone operator certificate still applicable Regulation 133. Conditions to be met before Australian aircraft may fly Regulation 139. Documents to be carried in Australian aircraft Regulation 155. Flight rules - acrobatic flight Regulation 157. Flight rules - low flying Regulation 207. Requirements according to operations on which Australian aircraft used Regulation 208. Number of operating crew Regulation 230. Starting and running of engines Subregulation 242 (2). Testing of radio apparatus Regulation 252. Provision of emergency systems Regulation 258. Flights over water  
    Exemptions common to 95.10 and 95.32 only
    Part 4. Airworthiness requirements Part 13 division 4. Lights to be displayed by aircraft Regulation 166A (2) (f) maintaining track from take-off until 500 feet [only in respect of powered parachutes ]  
    Exemptions common to 95.32 and 95.55 only
    Regulation 210. Restriction of advertising of commercial operations; insofar as advertising of flying training to qualify for a pilot standard specified in the RAAO Operations Manual is concerned Note: the prior exemption to CAR 252A dealing with carriage of emergency locator transmitters was rescinded in April 2011.  
    Exemptions applying to only one CAO
    Part 7. Navigation logs [unique to 95.32] Regulation 36A. Use of aircraft material in the maintenance, servicing and operation of Australian aircraft [unique to 95.55] Regulation 37. Permissible unserviceabilities [unique to 95.55] Regulation 163AA. Formation flying [exemption unique to 95.32 facilitating airtow of hang-gliders]
    7. The design and airworthiness certification Orders for powered recreational aeroplanes
    Civil Aviation Order 101.28
    CAO 101.28 is a combination of rules – originally promulgated in 1976 – covering the airworthiness certification requirements, and design standards, for light general aviation aeroplanes in the Amateur Built Aircraft Acceptance [ABAA] category. For ultralight aeroplanes the limitations expressed in CAO 95.55 paragraph 1.2 (a) over-ride the weights and stall speeds given in CAO 101.28. The aircraft is to be used for educational or recreational purposes and the owners construction input must be more than 50% of the total construction input.The general design standards are in accordance with the U.S. Federal Aviation Administration's FAR Part 23 or the British Civil Airworthiness Requirements Section K. The flight handling quality standards are also in accordance with FAR Part 23. The full CAO 101.28 can be viewed in pdf format.

    The ABAA certificate is an acceptance by the CASA that the aircraft complies with CAO 101.28. CAO 101.28 is not a standard acceptable in the ICAO sense, so any CoA (for a CASA registered aircraft) under 101.28 is not an ICAO recognised CoA. It is only recognised in Australia as qualifying the aeroplane to be registered on the national register as VH-xxxx. In view of the legislative minefield involving Certificates of Airworthiness and the ICAO convention, it is to DCA's (the old Australian Department of Civil Aviation ) great credit that a system was developed and is continuing in Australia giving national registration and its attendant privileges to 'Home Built' aeroplanes under CAO101.28.

    Note too that the building process involved strict control under the eye of the CASA , and while the regulatory authority of the day actually performed surveillance on the building process, this activity was delegated to the Sport Aircraft Association of Australia (SAAA). CAO 101.28 has been "sunsetted" in CASR 21.190 and ABAAs for new types were no longer issued after 30 September 2000. New types are now covered under CASR 21.191 which introduced the Experimental Amateur Built category. These aircraft require no building supervision, are registerable as VH although operational restrictions apply until they are removed under the authority of a 'CASA Delegate' – if the aircraft can meet the necessary requirements.

    Civil Aviation Order 101.55
    All commercially manufactured and sold recreational and GA aircraft should be designed to an acceptable standard, certificated as meeting that standard, and manufactured under a Certificate of Approval of the production and quality assurance process. CAO 101.55 is a set of rules covering the aircraft certification requirements for a TC or Certificate of Type Approval – including minimum design, manufacture, operational and safety standards – for commercially-built single-engine/single-propeller very light aeroplanes and kits. Take-off weight not exceeding 450 kg and Vso not exceeding 40 knots CAS [Vs1 45 knots]. Under some conditions these figures may be increased to 480 kg and 42 knots CAS. The aircraft may have no more than two places.

    Under CAO 101.55 the aircraft must comply with one of the three following international design standards:
    the U.S. Federal Aviation Administration's FAR Part 23 the British Civil Airworthiness Requirements Section K the European Aviation Safety Agency's certification specification CS-VLA (formerly JAR-VLA) which is the very light or sports aircraft legislation covering one or two place, non-aerobatic, VMC only aircraft up to 750 kg* MTOW, 45 knots maximum Vs1 and a type certified engine. or some other acceptable standard or combination of standards. CAO 101.28 encloses only FAR Part 23 and BCAR K. It should be mentioned that neither airworthiness certification CAO mandates the establishment of a safe fatigue life for the airframe or components.

    CAO 101.55 also mentions the requirement for noise certification:
    9.1 General. The Air Navigation (Aircraft Noise) Regulations 1984 introduced noise certification for aeroplanes subject to ANRs [CARs] with effect 2 August 1984.
    9.2 The noise certification scheme applies noise standards to aeroplanes to which this section of the CAOs apply. It is the applicant's responsibility to apply to Airservices Australia for the issue of a noise certificate.

    *Note 3: Since November 1996 the published RA-Aus policy has been that the MTOW for aeroplanes registered by RA-Aus that have been CS-VLA certificated [to 750 kg] could be extended to the 750 kg of the European design standard, or any other suitable design standard that allows 750 kg. CASA had a low priority certification project [CS 06/01] underway which might have resulted in the inclusion of that change in CASR Part 103 but CASA decided not to proceed with CS 06/01 and it was closed 9 October 2009.

    The full CAO 101.55 (2004 issue) can be viewed in pdf format.

    8. The proposed CASR Part 103 'Sport and recreational aviation operations'
    Part 103 will apply to all manned balloons and hot-air airships; powered aeroplanes; gliders including sailplanes, hang gliders, paragliders and their power-assisted variants; rotorcraft including gyroplanes, gyrogliders and other light rotorcraft. It generally substitutes for Part 91 in sport and recreational aviation, see NPRM 0603OS.

    For the purposes of Part 103 the powered recreational aircraft will be divided into two classes:

    The first powered class covers aeroplanes that have only one seat, MTOW no more than 300 kg (plus allowances of 35 kg if equipped to land on water and 20 kg for a recovery parachute system) and a maximum wing loading of 30 kg/sq.m. There is no restriction on the number or type of engine/s or propeller/s, stalling speed or maximum level flight speed. Thus, this class perpetuates the fundamental CAO 95.10 concept and will consequently be identified as 'low-momentum ultralight aeroplanes' rather than '95.10 aircraft'.

    Note: momentum equals mass × velocity so 'low momentum' does not necessarily infer a low maximum cruise speed, such as the 55 knots specified in the United States FAR Part 103.

    The second powered class covers all aircraft that have one or two seats, MTOW no more than 600 kg (plus an allowance of 50 kg if equipped to land on water) and (for aeroplanes) a maximum stalling speed in the landing configuration (i.e. Vso) of 45 knots CAS. This category also includes the gyroplanes (maximum rotor disc loading 20 kg/sq.m.), powered-parachutes and weight-shift aeroplanes (but not power-assisted sailplanes) that meet the criteria, but there is no additional weight allowance for water landing or recovery parachutes.

    Thus, any single-engine, one or two-place, land aircraft with MTOW less than 600 kg (and any similar aircraft equipped to alight on water with MTOW less than 650 kg) may be eligible to operate under Part 103 if Vso does not exceed 45 knots and it is accepted for RAAO registration.

    Existing aircraft operating within CAO 95.32 and CAO 95.55 limits, and others that do not conform to the new standard, will continue to operate as now in accordance with the RAAOs procedures manuals; i.e. the Operations and Technical Manuals. Such aircraft will still be limited to the lower of their design weight or type certificated weight. Factory-built aircraft may be able to operate at the 600 kg weight if certified to that or higher weight. As in the past the RAAO procedures manuals will continue to be subject to CASA approval scrutiny before amendment/re-issue.

    The acceptable CASA standards for design and performance of recreational aircraft are:

    Fixed-wing, 3-axis aircraft
    ASTM LSA standard F2245 (USA) British Civil Airworthiness Requirements Section S [BCAR-S/CAP 482] Small light aeroplanes European Aviation Safety Agency Certification Standard – VLA (ex JAR-VLA) CAO 101.55 (Australia) DaeC (BFU) 10/95 (Germany) UL/2 PT2 (Czech Republic) PICA 26 (Australian airworthiness design requirements for aeroplanes of conventional design in the primary and intermediate category – CASR Part 26; however the PICA 26 standard is no longer sponsored or maintained by CASA) DS 10141E (Canadian microlight) Plus any existing or recognised aviation standard acceptable to the CASA; e.g. FAR Part 23.
    ASTM LSA standard F2352-04 (USA) British Civil Airworthiness Requirements Section T ASRA Gyroplane Spec (Australia)
    Lighter-than-air aircraft
    ASTM LSA standard F2355-05 (USA) BCAR Part 31– balloons (Britain) FAR Part 31– balloons (USA) CAO 101.54 (Australia) BCAR Q – airships (Britain) FAA AC-21-17-1– airships (USA).
    ASTM LSA standard F2244 (USA) BCAR Section S (Britain) DS 10141E (Canada).
    Weight-shift control aircraft
    BCAR Section S (Britain) DS 10141E (Canada).
    To be advised, but possibly a sub-set of the EASA certification standard CS-22.  
    9. The civil legislation governing sport and recreational aviation administration organisations
    Recreational Aviation Australia Incorporated [RA-Aus] is an association whose governance could be considered representative of other sport and recreational aviation associations.

    Operationally, RA-Aus is a sport and recreational aviation administration organisation operating under a constitution that defines the nature of the association and its governance. From an aviation safety viewpoint the organisation's governance and compliance are oversighted by CASA. Legally, it is a not-for-profit, member-based association incorporated under the Australian Capital Territory Associations Incorporation Act 1991 and consisting of ordinary members with voting rights, affiliated clubs and other types of members without voting rights.

    'Incorporation' is the creation of a legal entity which has rights and liabilities (e.g. to enter into employment agreements and legal agreements, own assets or borrow money) that are separated from its ordinary members. This means that any financial claim against the Association could only be pursued up to the extent of the Association's assets rather than (if RA-Aus was not incorporated) all of the ordinary members being liable for any claims against RA-Aus; but see rule 8 of the RA-Aus constitution. There are no shareholders, no one 'owns' RA-Aus or any part of it. Surplus income is used to further the objectives of the association, not to provide personal gain for members. If the association should be wound up the surplus property will be distributed in accordance with rule 38 of the constitution and the ACT Associations Incorporation Act.

    Because RA-Aus operations are not confined to the Australian Capital Territory, RA-Aus comes under the jurisdiction of the Australian Securities & Investments Commission [ASIC], who regard it as a registrable Australian body whose internal governance operates under its own constitution. Registrable Australian bodies include bodies corporate that are not companies, recognised companies, exempt public authorities, foreign companies or financial institutions. ASIC has assigned RA-Aus an Australian Registered Body Number [ARBN 070 931 645]; it is not a 'business' number. ASIC's only interest in RA-Aus is to ensure proper governance.

    RA-Aus is not required to provide financial statements to ASIC, only the personal details of current board members as changes occur; plus updated, certified copies of the constitution, so that if complaints are received from association members' ASIC can start calling on the board members.

    The Board. An incorporated association must have a committee responsible for managing the association. In RA-Aus the state member representatives, elected by the ordinary members for a two-year term, form a committee described as the 'Board' and its members are 'Board members' (not 'directors'). The board members may make by-laws for conducting its own proceedings and general management of the Association's affairs. By-laws proposed shall be notified to the ordinary members and take effect after 30 days from the time of such notification, subject to the approval of the Board. By-laws may be repealed, varied or added to at any time and from time to time by the Board.

    The operational and regulatory activities of RA-Aus are governed by the Operations Manual and Technical Manual, both of which are published and amended following approval by CASA. RA-Aus administers the Operations Manual and the Technical Manual on behalf of the CASA. The maintenance of the recreational aircraft airworthiness standards are governed by the provisions of the Technical Manual. Owners of sport and recreational aircraft are responsible for ensuring the standards expressed in the Technical Manual are met and maintained, and registration of an aircraft by the RA-Aus is not to be held out as certification that the aircraft is airworthy. Similarly, the standards for operations of sport and recreational aircraft are governed by the provisions of the Operations Manual. Owners/operators of recreational aircraft are responsible for their operation in accordance with the standards provided for in the Operations Manual.

    Sport aviation within RA-Aus is formulated by the constitution's 'Statement of Purpose' paragraph B3: '... to encourage, undertake and exercise control of competitions, sporting events, displays, tests, records and trials and to hold either alone or jointly with any other association, club, company or person, recreational aircraft meetings competitions (including international competitions), matches, exhibitions, trials and receptions and to accept, offer, give or contribute towards prizes, medals and awards in connection therewith ...'

    The Fédération Aéronautique Internationale (FAI) was founded in 1905 and is the international governing body for air sports and aeronautical world records. The FAI Sporting Code deals with three major areas: firstly, organised sporting events such as championships and competitions, secondly, records, and thirdly the validation of specified performances for Certificates of Proficiency or Colibri badges. The Australian Sport Aviation Confederation (ASAC) is the national confederation of sport and recreational aviation organisations (the ABF, GFA, HGFA and APF) acting as a lobbying body in respect to Commonwealth and State governments and Commonwealth aviation authorities. RA-Aus is not a member.

    Before issue 6 of the RA-Aus Operations Manual was promulgated in 2008, section 1.03 of the manual was a statement of the duties and responsibilities of the National Flying Coach (NFC). Duty item 1 was 'Plan and formulate flying competitions at state, national and international level'. Item 6 was 'Consult with the FAI [Federation Aeronautique Internationale], the Australian FAI representative and member bodies to ensure that competition terms are kept up-to-date'.

    The NFC was active until 1997/1998; since then there has been no NFC appointment, even though the statement of duties and responsibilities for the position continued in the CASA-approved manual until 2007, and paragraph B3 of the constitution has not been rescinded.

    1. Accreditation of RA-Aus maintenance personnel
    Aircraft conforming to and operated in accordance with the Civil Aviation Orders CAO 95.10, CAO 95.55 and CAO 95.32 are exempt from those Civil Aviation Regulations listed in the CAOs. The exemptions include CAR Part 4A Maintenance so RA-Aus assumes responsibility for specifying the maintenance requirements for aircraft registered with the administration organisation and thus, has responsibility for accrediting suitably qualified and experienced individuals to conduct maintenance on RA-Aus aircraft. See the Technical Manual maintenance policy.

    Note that the 2007 Technical Manual section Accreditation of persons suitable to conduct maintenance currently states that RA-Aus pilots are automatically granted minimum qualification RA-Aus 'Level One Maintenance Authorities' but RA-Aus pilots are now no longer automatically granted RA-Aus Level One Maintenance Authorities with receipt of their Pilot Certificate.

    Practically all pilots-in-training do not own an RA-Aus aircraft nor do 60% of RA-Aus pilot certificate holders and those non-owner pilots have no need for any maintenance authority qualification. It is probable that, during 2015, all RA-Aus aircraft owners who hold a current Pilot Certificate and who elect to maintain Level 1 maintenance accreditation will be required to complete a syllabus of competency-based training and some form of examination to demonstrate sufficient knowledge of the required tasks before being granted Level 1 maintenance accreditation under revised rules.

    To facilitate maintenance, four levels of RA-Aus Maintenance Authority certification are available to members:
    Level 1 Maintenance Authority: aircraft owners must undertake a qualification test before performing the maintenance tasks for which they are judged competent and also to authenticate in the aircraft logbook the maintenance performed. They are qualified only on their own aircraft, provided the aircraft is not used for hire-and-reward e.g. flight training — or for glider towing. If the owner is not competent to perform a particular task and chooses not to undertake the necessary training, then that task should be assigned to a suitable Level 2 (or higher) holder or done under the supervision of the Level 2. If an owner-pilot does not choose to do any maintenance then level 1 qualification is not necessary and the owner must arrange for a competent Level 2 (or higher) person to perform and authenticate all maintenance, including the daily inspection.

    The trial online L1 Maintainer Authority Training and Assessment package comprises: A Study Guide to lead trainees through a series of questions and answers designed to provide them with a sound understanding of the privileges and responsibilities as an L1 maintenance authority holder. A range of reference materials are provided by way of links. Aircraft must be inspected and maintained in accordance with aircraft manufacturers' manuals. In some cases aircraft do not have such manuals, these aircraft must be inspected and maintained in accordance with acceptable aviation maintenance methods and practices. The FAA have produced a range of documents which provide guidance as to what are considered to be acceptable methods and practices. A link to this publication is also provided in the study guide. Assessment - when prospective L1s feel confident about their ability to answer questions about maintaining their aircraft, they may sit the online assessment. The assessment is an open book, 50 question, multi-choice examination with a time allowance of 3.5 hours requiring a score of 40/50 to achieve a pass. Level 2 Maintenance Authority: for suitable persons to conduct paid maintenance on owner-pilot aircraft or conduct and/or authenticate maintenance on aircraft used for hire, flight training and glider towing. Level 2s may have restrictions related to aircraft or engine type.

    Level 2 accreditation is awarded on the basis of qualifications and experience of each applicant, is valid for two years and only while the holder remains a financial RA-Aus member. See the current list of about 400 accredited L2 maintenance persons.

    Restricted Level 2 accreditations are deemed to be able to perform line maintenance on training aircraft or aircraft used for hire-and-reward, unless as otherwise defined by the RA-Aus Technical Manager. Note that those defined line maintenance items are much the same as the list of maintenance that may be carried out on a General Aviation Class B aircraft by a pilot entitled to do so under CAR 42ZC / CAAP 42ZC-1(2) but be aware that CAR 42ZC is part of CAR 1988 Part 4A and thus is not applicable to RA-Aus pilots.
      Level 3 Maintenance Authority: for about 20 suitable persons to act as regional supervisors, coordinators and points of contact for maintenance activities. The RA-Aus Technical Manager appoints Regional Technical Officers [RTOs] when suitable persons are available. The duties of the RTO include assistance to the Technical Manager in conducting Level 2 maintenance checks on aircraft used in flight school operations, as requested by the Technical Manager. See the current list of all accredited Level 3: Regional Technical Officers.
      Level 4 Maintenance Authority: for suitable and accredited persons to act as Amateur Built Inspectors in addition to performing the same tasks as defined at Level 2. RA-Aus certificates for the purposes of an Amateur Built Inspector rating are issued on receipt of the appropriate requirements. To be eligible for an Amateur Built Inspector approval, the applicant will generally be a CASA Licenced Aircraft Maintenance Engineer [LAME] in engines or airframes and be a financial member of RA-Aus. See the current list of about 80 accredited Amateur Built Inspectors.
    2. Maintenance authentication
    The elements of maintenance are what to do, when to do it and how to do it.

    Maintenance authentication is the action of a suitably qualified person annotating the aircraft maintenance log book underneath the listing of all maintenance carried out at that time and formally indicating that the work conducted is to the standard specified in the RA-Aus Technical Manual. The authentication is made by signing the aircraft maintenance log book, printing name and initials, RA-Aus membership number, aircraft/engine hours and the date.

    The authentication act is equivalent to signing a maintenance release (i.e. releasing the aircraft for normal flying operations or certifying that the aircraft is fit to fly) even though in most cases the aircraft owner is both the accedited maintainer and the pilot. This can constitute quite a character challenge — and test of responsibility and discipline — when the pilot personality is itching to go and the maintenance technician personality knows there are a few minor things that need attention.

    The daily inspection [DI], before the start of flying operations on each day that the aircraft is to be flown, may be completed by the owner-pilot with an L1 maintenance authority or the holder of an L2 authority. A log book authentication is required.

    Where there is a group-owned aircraft one owner must be appointed to be responsible for — and control of — all maintenance on that aircraft. That one person is to list in the log book all maintenance carried out and sign-off the authentication.

    3. RA-Aus maintenance policy
    Owner-operated aircraft
    Maintenance to owner-operated RA-Aus aircraft is the sole responsibility of the owner(s).

    The selection of appropriate maintenance schedules and the qualifications and experience of persons to complete the maintenance on the non-LSA privately-built and amateur-built categories in CAO 95.10 and CAO 95.55, is the responsibility of the owner.

    Maintenance conducted on the factory-built and the LSA kit-built aircraft categories in CAO 95.32 and CAO 95.55, shall be in accordance with the manufacturers' maintenance/service manuals and schedules including all supplementary service instructions, service letters and service bulletins issued from time-to-time.

    Where such a schedule does not exist or a copy cannot be obtained, the Technical Manual's 'Maintenance schedules and periodic inspections' document must be followed.

    The U.S. Federal Aviation Administration produced a substantial 613 page A4 size advisory circular AC 43.13-1B titled 'Acceptable methods, techniques and practices — aircraft inspection and repair'. Such methods are acceptable when there are no manufacturer repair or maintenance instructions. The AC generally applies to relatively minor repairs. A PDF version of the book is included in the RA-Aus Members' CD or a hard copy may be purchased from the RA-Aus shop. For an example of the contents the safetying section of AC 43.13-1B is available in html format in the 'Builders guide to safe aircraft materials'.

    Note: an example of a manufacturer's service manual can be downloaded from the Jabiru website. Scroll down the left-hand frame of their home page, click 'Manuals' then scroll down to 'Aircraft technical manuals' and click 'J160 J170' — it is a 15 MB pdf file.

    Aircraft used for hire-and-reward
    Only factory-produced aircraft may be offered for hire-and-reward; i.e. flight training — other than the CAO 95.55 para 1.5 aircraft used for flight training of the aircraft builder or builders. Aircraft used for hire-and-reward are to be wholly maintained, and/or the maintenance authenticated by, a Level 2 Maintenance Authority holder. Daily inspections may be completed by the pilot-in-command.

    A solo check flight after scheduled maintenance in accordance with the manufacturer's schedule is mandatory before the aircraft is used for hire-and-reward. Successful completion of this check flight is to be recorded in the aircraft log book and signed for by the Level 2 accredited person who conducted the technical work and the pilot who conducted the flight.

    Engine controls, engine accessories, propellers and flight controls are regarded as critical maintenance items and should be checked by an independent person after any maintenance. This applies to both owner-operated aircraft and hire-and-reward aircraft.

    Aircraft used for glider towing
    An aircraft used for glider towing has to be both certified for glider towing by the manufacturer and accepted by the Gliding Federation of Australia [GFA]. The GFA also approves the pilot, even if they have an RA-Aus glider towing endorsement. Maintenance must be carried out by a Level 2 accredited person, in accordance with the manufacturer's glider towing supplement, or a GFA approved maintenance scheme or one approved by the RA-Aus Technical Manager.

    4. Technical Manual issue 3 maintenance section
    Maintenance section contents:

    4.0 Policy
    Annex A Maintenance tasks and authorities required
    4.1 Accreditation of persons to conduct maintenance on recreational aircraft
    4.1.1 Criteria for assessment of RA-Aus Level 2 Maintenance Authorities Annex A maintenance supervisor questionnaire (attached to the 4.1.1 document) Annex B Definition of line maintenance
    4.2 Inspection of recreational aircraft
    4.2.1 Daily and pre-flight Inspections 4.2.2 Inspection after assembly 4.2.3 Inspection after heavy landing 4.2.4 Periodic inspections Annex A Maintenance schedules and periodic inspections (attached to the 4.2.4 document) 4.2.5 Piston engine continuing airworthiness requirements Appendix A four-stroke piston engine condition check (attached to the section 4.2.5 document) Annex A four-stroke piston engine cylinder leak check Annex B four-stroke piston engine condition report Annex C two-stroke piston engine check [not yet finalised]
    4.3 Defect reporting and airworthiness notices
    Annex A: Aircraft defect report (attached to the section 4.3 document) Annex B: Aircraft airworthiness notice (attached to the section 4.3 document)
    4.4 Repairs

    4.5 Log books and other records

    5. The 2008 FAA Aviation Maintenance Technician Handbook
    Recrational aircraft owners or potential owners may find portions of this handbook informative.

    "The Aviation Maintenance Technician Handbook – General was developed as one of a series of three handbooks for persons preparing for mechanic certification with airframe or powerplant ratings, or both. It is intended that this handbook will provide basic information on principles, fundamentals, and technical procedures in the subject matter areas common to both the airframe and powerplant ratings. Emphasis in this volume is on theory and methods of application. The handbook is designed to aid students enrolled in a formal course of instruction preparing for FAA certification as a maintenance technician, as well as for current technicians who wish to improve their knowledge. This volume contains information on mathematics, aircraft drawings, weight and balance, aircraft materials, processes and tools, physics, electricity, inspection, ground operations, and FAA regulations governing the certification and work of maintenance technicians. New to this volume is a section addressing how successful aviation maintenance technicians incorporate knowledge and awareness of ethics, professionalism, and human factors in the field."

    Note: the chapters are contained in large PDF files.
    Cover, Preface, and Table of Contents Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Glossary Index The FAA advisory circular AC 43.13-1B 'Acceptable methods, techniques, and practices — aircraft inspection and repair' (~ 650 pages and incorporating the 2001 changes) is available from the RA-Aus online shop for about $50. It is bound together with the FAA advisory circular AC 43.13-2A 'Acceptable methods, techniques, and practices — aircraft alterations' (~ 100 pages). Some of the information in this book — manufacturer's part numbers for example — may be out of date.

    The next module in this 'Joining sport and recreational aviation' series discusses the legislative framework that enables Australian sport and recreational aviation

    7.1 What is airmanship?
    The definition of airmanship is somewhat indistinct. With the introduction of computerised control systems, the application of airmanship is certainly more broadly based and complex now than 50 years ago. Some might say it involves pilot proficiency, flight discipline, aircraft system and airworthiness knowledge, and skill in resource management, plus being fully cognisant of every situation and exercising excellent judgement. A few years ago someone did say — in relation to the management of airline transport aircraft — airmanship is "the ability to act wisely in the conduct of flight operations under difficult conditions". If that is valid then the three-pilot flight-deck crew of Air France Flight 447, with 20 000 flight hours experience, failed their crucial airmanship test on June 1, 2009.

    The author's definition is reasonably applicable to sport and recreational aviation:
    Good airmanship is that indefinable something, perhaps just a state of mind, that separates the superior airman/airwoman from the average. It is not particularly a measure of skill or technique, nor is it just common sense (i.e. the normal understanding and judgement we should all have). Rather, it is a measure of a person's accumulated learning — their knowledge and awareness of the aircraft and its flight environment, and of their own capabilities and behavioural characteristics; combined with good judgement, wise decision-making and attention to detail in the application of that learning; plus a high sense of self-discipline.

    Airmanship is the cornerstone of pilot competency.
    Competency has been defined as the combination of knowledge, skills and attitude required to perform a task well or to operate an aircraft safely — in all foreseeable situations.

    For example, here is an extract from an RA-Aus incident report: "The aircraft, with instructor and student on board, was returning to the airfield when a pitch-down occurred. Not known to them the elevator control horn assembly had failed. Control stick and trim inputs failed to correct the situation, but a reduction in power did have some influence, though not enough to regain level flight. A satisfactory flight condition was achieved by the pilots pushing their bodies back as far as possible and hanging their arms rearward. A successful landing at the airfield was accomplished."

    A flight operation, even in the most basic low-momentum ultralight, is a complex interaction of pilot, machine, maintenance, practical physics, airspace structures, traffic, weather, planning and risk. When every flight is undertaken, it is not only the aircraft that should be airworthy; the total environment — flight planning, airframe, engine, avionics, atmospheric conditions, pilot condition and aircraft handling — should allow for the safe, successful conclusion of each operation. It is the perception — founded on the acquired underpinning knowledge — of the state of that overall flight environment and its potential threats that provides the basis for good airmanship and safe, efficient, error-free flight. Insufficient perception and insufficient self-discipline create a pilot at risk.

    The bulk of sport and recreational aviation is undertaken by 'amateur' pilots (using the original meaning of the term; i.e. a lover of a particular activity or pastime), but such pilots must still approach aviation with the continuing diligence of a professional. Less experienced pilots must acquire levels of airmanship consistent with their progress along the aviation learning curve.

    Ensuring engine and/or airframe airworthiness prior to flight is a prime component of airmanship. Owner-pilots are totally responsible for the continuing maintenance of their aircraft, be it a hang glider or a high performance aeroplane. However — for the person accepting an aircraft they do not own/operate — airworthiness, unfortunately, is a matter of faith in the operator, and in the accuracy and completeness of the aircraft's maintenance record. Daily inspections and pre-flight checks cannot assure airworthiness — the pilot does not know what is hidden under the skin or within the engine.

    Just as the term 'seamanship' implies a full appreciation of surface wave action and sea movement, so 'airmanship' implies a full appreciation of atmospheric waves, eddies, thermal activity and turbulence.

    7.2 Risk management
    Most sport and recreational pilots accumulate only a small number of hours each year; about two-thirds of powered aircraft fly less than 60 hours. Perhaps such annual hours is enough to maintain physical flying skills learned at the ab initio flight school — if the pilot has established a program for self-maintenance of that level of proficiency — but maybe not enough to maintain a high level of cognitive skills; for example, situation awareness, judgement and action formulation. In addition, having completed flight theory studies sufficient to pass the basic aeronautical knowledge test and achieve the RAAO's Pilot Certificate, it seems that many, perhaps most, pilots leave it at that — so failing to expand their knowledge by further in-depth studies of flight dynamics and the application of the acquired knowledge; possibly because it involves sometimes difficult detail rather than the broad-brush approach of the flight school. Or, perhaps, assuming that the necessary knowledge will be acquired through subsequent flight experience, also assuming (I guess) that they will survive every learning experience in a condition to continue flying.

    However, many pilots are just continually repeating the same flight experience — each year is the same as the last — so all they accumulate is a repetition of one year's experience. They have no program of deliberately advancing knowledge and skills, nor have they really absorbed the safety basics that should have been drummed into them over the years — never turn back following EFATO; always maintain a safe airspeed; if the engine has been misbehaving never take off until the problem is identified and fixed; if the engine goes sick in flight don't try to make it back to base, land ASAP; don't continue into marginal conditions — turn back; and so on.

    So a safety problem exists with some pilots. Many are just not ensuring that they accumulate adequate post-certificate knowledge and skills. In short, they never really learn much about flight dynamics and the atmosphere (and some of their accumulated beliefs are dangerously false); they lack other pertinent knowledge; and worse, they are just not listening or hearing. Be assured that every pilot needs to know more.

    The sound pilot must understand how the environmental parts relate and interact with each other, and judge the likely consequences of any action, deliberate non-action or random event. A systematic approach to continuing improvement in airmanship, plus an ability for self-appraisal, is necessary to achieve that understanding. The Flight Manual or Pilot's Operating Handbook for the powered aircraft model being flown must be fully understood, and the content recollectable when needed in an emergency. Every flight should be conducted correctly and precisely, using procedures appropriate to the airspace class and without taking shortcuts, even if just a couple of circuits and landings are contemplated.

    To paraphrase Louis Pasteur's 1754 observation: 'Chance favours only those who have prepared'.

    Pilots should be aware that fatigue, anxiety, emotional state — or flying an aircraft that stretches their skill level or just flying an aircraft they don't like — will affect perception and good judgement. See the "I'M SAFE" checklist. Most studies of aircraft accidents or incidents reveal not a single cause but a series of interrelated events or actions that, being allowed to progress without appropriate intervention from someone, lead to an unplanned termination of the flight.

    A U.S. Navy pilot once wrote "In aviation you very rarely get your head bitten off by a tiger — you usually get nibbled to death by ducks." However, U.S. Navy pilots are well-trained, well-informed, self-disciplined individuals who do not expose themselves to those situations where eventually the tiger WILL bite your head off.

    Many years ago, the gliding community demonstrated that there were two main cyclic periods (for them) where people were accident prone. This was about the 100-hour mark, where pilots were beginning to think they were immortal, and about 200–250 hours when they were sure they were; being survivors of the incidents of the first period.

    Dr Rob Lee, the then Director of the Australian Bureau of Air Safety Investigation, wrote in 1998:
    "Over 40 years of investigation of General Aviation accidents by BASI and its predecessors clearly shows that while the immediate circumstances of each accident may well be unique, the underlying factors are always drawn from the same disturbingly familiar cluster — pre-flight preparation and planning, decision making, perception, judgement, fuel management and handling skills".

    A study of the factors contributing to fatal general aviation accidents in Australia for the ten years 1991–2000 showed that inadequate flight planning was a factor in 38% of the accidents, aircraft handling errors in 30%, and fuel starvation or exhaustion in 10%.

    7.3 Situation awareness
    (The Australian Civil Aviation Safety Authority's 2009 publication 'Safety behaviours - work book for pilots' © CASA includes airmanship and situation awareness text from this page.)

    Being situationally aware means to be fully cognisant of the big picture at all times, by continually collecting and judging information from sources inside and outside the cockpit. In flight, a pilot has to be thinking several minutes ahead of the aircraft, not several seconds behind it — to perceive what's going on and be able to impose sound judgement on every change, from a minor distraction to a major in-flight emergency. Stress may build rapidly in an emergency situation and the pilot will tend to unconsciously focus on a very few aspects of the situation, without noticing that other aspects are degrading — airspeed or attitude for example. Good handling of any unusual situation — particularly the first major emergency — provides a basis for confidence in abilities. Poor handling of an emergency will undermine confidence.

    (Note: I have used the term 'situation awareness' throughout the various guides rather than the more commonly seen 'situational awareness'. This is to accord with the official documents CAAP 5.59-1(0) , CAAP 5.81-1(0) and the CASA day VFR syllabus – aeroplanes (PPL and CPL). CAAPs provide recommendations and guidance to illustrate a method, or several methods by which legislative requirements may be met. ... JB)

    There is much written on the ways to improve situation awareness but it boils down to a few basics: Assimilate an adequate knowledge base. To enable appropriate judgements and manage threats — or your errors — you must have sufficient underpinning knowledge of all relative aspects of flight, of human limitations and of the aircraft you are flying.
      Plan well in advance with a properly researched weather forecast and flight plan. Pre-flight planning may start days before a flight. Even local flying should be preceded by looking at a met forecast the evening before — to compare against the conditions you find and how the sky really looks. You must know the aircraft's take-off and landing capability in the existing or expected environment.
      Continually monitor flight progress against that plan, re-evaluating where necessary and implementing alternatives as soon as the need becomes apparent.
      Develop and use a scanning technique that takes in engine instrument indications, flight instrument indications, aircraft heading, flight path (60° left, ahead, 60° right, above, below), time, map and ground. Develop a scanning pattern that covers everything without becoming superficial but also allows time to be allocated to individual scan segments according to your perceived needs. For scanning techniques read 'Eye on the sky' in the September – October 2003 issue of Flight Safety Australia. For a research report on the limitations of the VFR unalerted 'see-and-avoid' principle read this 1991 ATSB report. For a description of the pilot's role in collision avoidance read the FAA advisory circular AC90-48C.
      Project ahead and rehearse your actions — for example:
    "The next checkpoint will be in sight in …"
    "If the next checkpoint doesn't appear as scheduled I will … "
    "If the cloud is not as high as it appears or there is more of it than there appears I will …"
    "If an aircraft appears on a straight-in approach I will …"
    "If the engine packs up soon after lift-off I will …"
    "If the engine packs up above 200 feet I will …"
      Avoid locking on to a problem, a task — or, for instance, your intended landing point — for too long, don't keep your head in the office, keep the scan going, be aware of the relative position and movement of other traffic, hold the heading and fly the aircraft at a safe airspeed appropriate to current atmospheric conditions and your height above the surface and obstructions.
      When operating at or in the vicinity of airfields, use a radio transceiver to communicate your position and intentions to other aircraft. Listen out for those key words that indicate other aircrafts' positions and intentions. Be aware that not all aircraft will be radio-equipped and even those that are may not be listening out on the appropriate frequency. Project ahead to plan safe and orderly traffic separation — most light aircraft mid-air collisions and near-misses occur in the vicinity of an airfield.
      In short — be well informed, plan well in advance, fly to that plan, continually monitor flight progress, use a scanning technique and be aware. Know where all other aircraft are and their intentions, communicate when appropriate, project ahead and, above all, don't be distracted — fly the aircraft and fly it at a safe speed and within your limits and the aircraft's performance limits.  
    7.4 Self-discipline
    The reason for choosing to ignore the established rules is usually to save time or money, coupled with the belief that they will get away with it because 'It can't happen to me' or 'It'll be okay'. Sometimes, particularly when they flout the laws of physics or aerodynamics, it is either pure bravado or wanton disregard (i.e. plain stupidity), or maybe it is just lack of knowledge.

    There are — fortunately only a few — rogue pilots in the various aviation communities who believe that the rules, written or otherwise, are stupid or unnecessary, and so determine to flout them. Such people ignore the trail of injury and death, stretching back over most of the 20th century, which formulated the rules and conventions. Each conscious infraction of those rules further dulls good judgement until crunch time finally arrives and, unfortunately, such rogues often take others with them. All pilots have a moral responsibility to inform a passenger, intending to fly with a person known to engage in illegal or doubtful activities (e.g. unauthorised low flying or inappropriate manoeuvres around the airfield), that flight with that person is inadvisable. If a person is known to consistently indulge in illegal or dangerous flight then there is a responsibility to inform an appropriate authority — police, CASA, RA-Aus, HGFA, etc.

    All pilots must occasionally ask themselves the question: Am I maintaining a fully disciplined approach to all flight and pre-flight procedures? And if not — why? Good airmanship cannot co-exist with poor discipline. A self-evident truth is that a pilot lacking the appropriate self-discipline is an accident in preparation.

    Discipline overrides panic and reinforces the ability to maintain/regain control of the aircraft when faced with a serious flight situation.

    7.5 Rules, regulations and common sense
    Not even the most experienced pilot, flying maximum hours every year, can judge the probability of all likely outcomes in any situation, expected or unexpected, and make the appropriate decisions. For that reason, among others, a system of regulations, rules, conventions, practices and standard procedures exists for recreational and sport aviation — and all other aviation communities — to follow. Once acquainted with them, these rules and procedures, plus commonsense practicality, generally provide an acceptable level of protection. But far too often, pilots and others — all of whom should know better — deliberately choose not to follow them and thus abandon that inherent protection.

    7.6 Personal operating procedures
    Standard operating procedures (e.g. joining the circuit, completing a flight note) are not included in the RA-Aus Operations Manual. However, every pilot should develop and follow their own set of personal operating procedures and apply them, where applicable, to each flight operation: e.g. a procedure to be followed if unsure of position on a cross-country flight; or turn-back if you find yourself flying toward rising terrain and a lowering cloud base; or having the self-discipline, when under time or other pressures, to decide whether you should take-off in the first place! If there is doubt about the weather, the wise pilot leaves the sky to the IFR-rated pilot in the IFR-rated aircraft. A non-IFR pilot caught out in instrument meteorological conditions [IMC], or dark night conditions, will be very lucky to survive.

    The dedicated pilot flies accurately, using approved technique, knowing the performance (i.e. the best rate) airspeeds for the aircraft being flown and consistently maintaining such airspeeds — and the chosen altitudes and headings. She or he will know the minimum safe speeds for various angles of bank when turning in level, climbing and descending flight — and at varying weights and cg positions. The pilot will know the aircraft's glide performance and, during flight, will be continually monitoring the ground for possible safe landing sites should the engine fail. Such pilots will have developed a set of tolerances for personal performance assessment; e.g. airspeed consistently within 5 knots, altitude within 100 feet or heading held within 5°. The dedicated airman or airwoman aims to fly with style, making smooth, timely and balanced transitions when turning, climbing, descending or levelling off so that the flight path flows, rather than being seen as a string of loosely connected manoeuvres. Every landing is a gentle arrival that doesn't strain any part of the aircraft.

    7.7 Human factors training
    The term 'pilot error' appears extensively in safety investigation reports but is generally a most unsatisfactory summation of an event and its causal factors. In the 1980s the International Civil Aviation Organization [ICAO], the administrative authority for the world's international air transport system, finally accepted the inevitability of human failure in flight, maintenance and other aviation operations. Consequently, in the late 1980s ICAO introduced 'human factors' [HF] training and assessment requirements for pilots (and others), and circular 227-AN/136 'Training of operational personnel in human factors' was issued. Effective August 2008, RA-Aus introduced human factors training to the flight training syllabus; consequently, from August 2008, all student pilots study HF in their training and, by 31 August 2010, all existing Pilot Certificate holders must complete an RA-Aus HF course or pass the RA-Aus written HF examination, or show other evidence of meeting the required competencies of the RA-Aus Operations Manual, section 3.09.

    The Australian Civil Aviation Safety Authority [CASA] also decided that, from 1 July 2009, threat and error management will be added to the existing human factor aeronautical knowledge examinations within their day VFR syllabus. The Civil Aviation Advisory Publication CAAP 5.59-1(0) 'Teaching and assessing single-pilot human factors and threat and error management' was published in October 2008 and is recommended reading. CAAP 5.59-1 links human factors with deficiencies in airmanship. The CAAP defines human factors as 'Optimising safe flight operations by enhancing the relationships between people, activities and equipment. This means: achieving the safest outcome for flight operations by the most effective use of people, and what people do when operating in the aviation environment and the equipment they use.'

    The 2009 CASA safety behaviours publication 'Safety behaviours: Human Factors for Pilots' is available. The pack consists of: Safety behaviours – resource guide for pilots (183 pages plus a CD) Safety behaviours – work-book for pilots (111 pages) Safety behaviours – facilitator's guide (15 pages) Guidance material – extract from CAAP 5.59-1(0) (42 pages) The pack can be purchased from the CASA online store for the cost of postage (one copy per person only).

    Further reading
    The online version of CASA's magazine Flight Safety Australia contains some articles relating to airmanship, which are recommended reading. A categorised index of articles of interest to recreational pilots contained in Flight Safety Australia since 1998 is available on this site. The articles are listed within ten categories together with a very short summary of the content.

    7.8 A CFI's viewpoint
    The late Tony Hayes, once CFI of Brisbane Valley Leisure Aviation Centre — and the inaugural holder of the RA-Aus Meritorious Service Award — published this airmanship interpretation.

    "Airmanship" — aviation could not exist in a responsible manner without this apparently intangible component. Let us define airmanship exactly so you do know what you are searching for to make your own, and thus achieve personal protection, pride, and protection of others, in your own standards of what you do, or propose to do.

    The big intangible is our personal attitude to flying — why we do it, how we do it. Do you care to define an individual's personal attitude to both flying and the environment in which that person's flying is conducted? Many things form our attitudes and we need to consider these if we wish to see airmanship as it really is — get a handle on it and make it our own.

    That is easy enough, but before we start — accept that airmanship is something that grows. It grows on experience whether shaped by training or by personal exposure to what you do. You cannot learn airmanship only from a book or an instructor, you are as much guided there by exposure to those circumstances, encountered with growing experience, which require airmanship.

    Whether it be flying training or airworthiness training — only the basics can be established. Like the runner in a relay race taking the baton — you have the potential winning element in your hand, it is up to you if you win or not, take on what you have been given, and make it work for both yourself and the others with whom you share the skies. Winning the airmanship race is not simply about staying alive or not bending yourself or aircraft — it is walking off the airfield relaxed, knowing you have not simply performed but have crafted an activity, and being totally aware you have enjoyed the sum of that and owe nothing to anyone.

    Let us start with a target to shoot for.

    Airmanship — a definition
    'A personal and situational management state required to allow a human being to enter and exit, in safety, an environment which they were not naturally designed to inhabit. This state comes into being immediately a decision is made that an aircraft is going to be flown and continues until you walk away from the completed flight and correctly secured aircraft.'

    That continuation may require an instinctive willingness to assess, between flights, the lessons that have been stated by the flight just completed. Airmanship is as much a ground-based attitude as it is an air-based one.

    Airmanship structure
    We are now going to look at the basics upon which airmanship is formed and therefore can be understood. We have already touched upon one — PERSONAL ATTITUDE — now we must put this in context with the others: KNOWLEDGE — SKILL — CONFIDENCE — RESPONSIBILITY. These four are then applied by personal attitude.

    The application of airmanship can be defined to three areas: the airworthiness of the aircraft the operation of the aircraft and the environment in which the aircraft operates. We will briefly examine each of these requirements and applications. All four requirements are intimately interconnected with each other and with applications, so cannot be treated entirely as stand-alone subjects.

    Knowledge • AIRWORTHINESS. You do not have to be a mechanical engineer to be a pilot but you do need to know sufficient about the aircraft structure and systems to enable you to safely pre-flight it and adequately monitor its continued satisfactory operation. The degree of knowledge required will depend upon the complexity of the machine and the range of environments in which the machine is capable of operation. (See the 'home builder' comment below.)   As pilots do not have to be engineers, there is therefore a supporting mechanical and engineering system to which the pilot will generally interface, via documentation, which revolve around periodic servicing and in-service defect reports. Understanding this system is part of the knowledge requirement such that you do appreciate whether the aircraft is provisionally serviceable or not — subject to pilot inspection.   • OPERATIONS. These are very much the pilot's responsibility and sufficient knowledge must be present for the safe operation of the aircraft within the parameters for which it has been designed. This knowledge must extend adequately from flight principles through to understanding of systems operation. All of this must then interface with the environment within which the aircraft will operate and this in turn requires understanding and application of airspeed limitations, manoeuvres permitted, weather minima (e.g. maximum crosswind limits), etc.   • ENVIRONMENT — Meteorology. The forces exerted by the ever-changing atmosphere upon an aircraft are far removed from those weather considerations we have knowledge of when we exist only on the ground. The pilot has to be able to read the sky like an advertisement, interpret current conditions and identify changing conditions along with the rate and degree of change. Decisions so made then have to be balanced with aircraft operational limits and the pilot's personal skill limits — usually this is a forecast being responded to before the situation has moved beyond estimated limitations.   — Behaviour controls. In simple terms this is knowing the 'rules of the road' in terms of rules of the air. From simple basics such as 'give way' rules, to airfield marking systems, to airspace restrictions — these are all designed to enable the present huge variety of aircraft to share airspace safely. They must be understood and instinctively applied by the pilot.   — Regulation. Partly from lessons learnt the hard way in the past, and partly due to an ever expanding population both in the air and on the ground — the information resource of who does what to whom is bound into regulation. The pilot needs to know this regulation as applicable to his or her operation, respect that others have different parameters they must follow and make allowance accordingly, plus have the regulation available and currently updated to suit the operations being conducted.
    This is an area determined, at least on the surface, by our ability to perform certain actions and procedures. But you can teach a bird to talk — that does not mean the bird understands what it is doing or can hold a conversation. Skill is underpinned entirely by knowledge and from this skill may be put in context and is capable of organised development based upon growing experience.
      • AIRWORTHINESS. The degree of skill in this area depends upon the level of airworthiness control you intend to apply. In pilot pre-flight terms, the skill will be certainly underpinned by a healthy element of curiosity — does it actually work and is it likely to stay in place! As we move further into servicing and repair, then hand and machine skills (adequately supported by appropriate knowledge) increase. For both control and convenience, divisions are made as to the degree of work which may be undertaken via various airworthiness maintenance approvals, each requiring higher knowledge and skill levels.   • OPERATIONS. As the aircraft you have access to become more complex then so the further you are removed from basic stick and rudder skills to new skills that are mainly founded upon systems operation and changing operating parameters. Those basic skills have to be totally and automatically in place, with sufficient competence of application supported by knowledge, such that the new skills may be safely founded.
    With this foundation, you may move from a simple aircraft to a slightly more complex one with some confidence and further acquisition of systems and operating parameters — but you should instinctively stop if you are clearly going beyond your existing knowledge and skill base until you have corrected that situation.

    There is another element to skill and that is currency. None of us, no matter how much we have flown, are any better than our next arrival on the ground. If we are not current (particularly with more complex aircraft, which require confident fluidity in the checks and procedures with their operation) then we could just be rolling the dice on the basis of 'been there, done that — she'll be right'. But even the simplest of aircraft will severely bite the 'out of practice' pilot. How much out of practice is 'out of practice'? The airman instinctively knows.

    Situational appraisal, how long out of practice, so many other things — all come into play here. As a command pilot, the airman will make a valid decision based on information and assessment, and react accordingly and safely.
      • ENVIRONMENT. In this situation we are less concerned about the tirades of the weather (although that has an obvious control upon how skill is intended to be employed). In airmanship terms we are more interested in the human environment of peer group pressure, personal needs to achieve a task, or (for some pilots) pressure applied by employers.
    Too often, a flight becomes driven by emotive pressure and/or need to complete a flight for personal gain (in so many forms). Emotion and personal gain are the two biggest killers yet invented by our race. Every year the figures continue going on the board in terms of deaths and wrecked aircraft — ran out of fuel, weather out of parameters, flew into lowering cloud base and rising ground. It still happens every year!

    As human beings we are never more vulnerable than when our skill is being questioned or challenged by others — or even ourselves, particularly in situations where by its very nature flying begins being interpreted as some 'personal courage combined with ability' thing. The true airman, with knowledge present and supporting skill in place, is dispassionate and evaluates situations on known and observed circumstances. Too often for some, tomorrow may indeed have been soon enough, but was not!

    Confidence can be underpinned by one simple control statement — 'If in doubt, don't'. If there is doubt, then confidence by definition does not exist. If you are not confident then you should not go.

    Confidence is formed by adequate levels of knowledge and skill. The airman has these in constant balance and sees a flagging of confidence as a natural warning bell — there is yet more work or revision to be done so that confidence is truly there. When those warning bells sound then it does not matter if the doubt concerns whether the aircraft is serviceable, or if you are up to the flying you are undertaking — time to take pause and look for additional abilities.

    There is also another element to confidence, and that is overconfidence. In this situation, even adequate knowledge and skill is being superseded by an emotive form of confidence. Once with a Pilot's Certificate achieved, the need to satisfy an instructor's discipline may fade, knowledge becomes steadily forgotten as a stimulus to what must be, and skill currency may go the same way. With the demand strictures of flying training now past, near enough may be good enough — forgotten is the need for why those original standards were set.

    Overconfidence meets its true ground in exhibitionist flying. In this situation the pilot is driven by ego, deliberately in front of an audience (which is mandatory) to show they are more than mortal and can really 'fly'. Unfortunately, the accident records confirm that such people are indeed mortal. Those tend to be the 'headlines' examples — but the run-of-the-mill situations are the greater number of people who bend themselves and/or aircraft — or — the much larger majority who narrowly avoid disaster, and hopefully become airmen as a result of that new demonstration of their inadequacy.

    If confidence cannot exist without knowledge and skill then the exercise of responsibility cannot exist without all three.

    Here the airmanship pattern may be disrupted and two opposites meet. A totally trained, knowledgeable and skilled pilot, under the influence of irresponsible behaviour, can be as discounted as the worst non trained aerial lout.

    Ultimately we are human. We are subject to human drives. So maybe there is another definition to airmanship — the self-discipline and wisdom to rise above our human condition and just be practical about what we do and where we do it.

    Within the ultralight community we have a sector of effort which is, via particularly CAO 95.10, but within overtones of 'amateur built' — an area where airmanship principles themselves may be seen by reflection. In this area, the intending pilot does have to embrace sufficient elements of the designer, engineer and aircraft constructor. The requirements for knowledge and skill are self-evident. Confidence will ultimately be expressed by a preparedness to fly the finished machine. Responsibility will be expressed by understanding that sufficient knowledge and skill was present to build the machine to an airworthy standard, but there is also equal knowledge and skill present in the operations area to ensure that the proving flights are conducted safely, responsibly and with validity. Near enough is never good enough on a new aircraft type.

    So the ultimate definition of airmanship, when seen in context with allied disciplines, comes down to quality of performance within prevailing circumstances — backed by quality of personal intent.

    Flying is fun — a pile of wreckage is neither. Between those two extremes is the ultimate expression of airmanship."

    The following document is an extract from the BVLAC flying training manual written by the late Tony Hayes. (The flying school has since ceased operations.)

    "For all my exposure to aviation — which extends over my entire life from my birth next to an operational bomber airfield in World War 2 — when I came to pilot training myself I met a term so commonly used yet nowhere could I find actually defined and explained, Airmanship. So I will fix that right now in my own flying training manual.

    The problem is understood once Airmanship itself is actually understood. It is very real and manifestations of it may be seen at every airfield or places people come to fly aircraft. Yet Airmanship is an intangible, for it is a state of mind, personal convictions and self discipline expressed in our actions and attitudes. It is the prudent operation of a machine, and the management of circumstances surrounding that operation, within an element we were not naturally designed to inhabit.

    Airmanship appears in every flying area and sets aside the airman from the aircraft driver. It is founded firmly in basic training where mental attitudes to flying are forged, and sometimes in self training where a pilot learns the hard way about what is prudent or not, gets away with it, and elects to make more sensible decisions at the right time, next time.

    Under growing experience airmanship may grow and blossom into a comfortable protective cloak, resting light upon the shoulders, worn perhaps with pride, but never in vanity, and giving the protection of 2 inch armour plate.

    The very need for its presence is a reminder that we are privileged to transit from our natural element into another. There may be a high price for such transition if that act is made in scorn or ignorance. But we may go there safely if we acknowledge the limitations of ourselves and our machines, so generating a curious mixture of humility and confidence which is expressed in the very form of airmanship.

    Airmanship may be performing a proper pre-flight check of an aircraft rather than a casual look-around. It is something as instinctively looking before turning. It is actually doing pre take-off and pre-landing checks — not mouthing the words. It is sensible pre-flight planning — either for a circuit or going over the horizon. It may be as simple as looking at the windsock before hitting the 'loud' lever, or as complex as interpreting a changing weather pattern. It is the essential personal and situational management difference between being up there wishing you were down here, rather than being down here wishing you were up there.

    But, founded on flawed training, or growing experience driven by a different pride, airmanship may wither into a deadly weed of contempt for those who slavishly obey 'regulation' or are not deemed 'good enough' to sort out situations as they happen. People driven by such views, in their ignorance, inhabit a perilous place of their own making wherein they have become an accident looking for somewhere to happen, and so ensure that it will happen.

    The non-airman will discount that the 'officious regulation' is (in the main) a book written in the blood of people who found out the hard way and handed down to us methods of avoiding their fate. In discarding that knowledge so is generated the certainty of the same fate, standing in the shadows, waiting.

    The airman is a person who maintains a valid skill and knowledge currency such that when the unexpected does happen there is ability and composure enough to manage the situation into safety. He or she, is a person with a sense of balance and intelligence enough to heed the lessons of the past, apply them in the present, and so ensure a future to be able to fly again, and again, and again.

    You will be hearing a great deal more about airmanship in your time with us, and now you know what we are actually talking about."

    Tony Hayes, CFI; Brisbane Valley Leisure Aviation Centre

    The next module in this 'Joining sport and recreational aviation' series concerns pilot maintenance of RA-Aus aircraft.

    1. Post-certificate learning
    The airmanship learning curve follows two contiguous paths. One is the airworthiness path where knowledge is sought — and accumulated — of the engine, airframe, propeller, avionics and instruments for each aircraft type encountered plus the skills and procedures required to maintain and repair airframes, engines and componentry. Thus the pilot is always able to assure an aircraft she/he intends to fly is fit for the operation, without being totally reliant on the opinion of others. Many people find advancement along this path most satisfying because it may eventually lead to building — possibly designing — your own aircraft.

    The other path is advanced flight training within the selected aircraft group, where knowledge should be sought about each aircraft's safe flight envelope and the safe handling practices required in various work and/or atmospheric and/or airfield environments. Some of this knowledge will be accumulated through ongoing experience and contact with others (via club membership, for example), much through self-instruction and experiment, but normally some has to be garnered through a fee-for-service provider. The providers are the Flight Training Facilities and the airworthiness training facilities that may be associated with an FTF.

    Basically any pilot has three choices. One, continue to do much the same type of flying experienced at the ab initio training school, i.e. fair weather, light winds, familiar places, similar aircraft and gentle flight. There is no increase in the quality of experience or competency — just an increase in quantity of time spent in the air — until it becomes uninteresting. Enjoyment and challenge cease, the learned skills then slowly erode and you remain a novice in aviation.

    The second choice is to perhaps expand your field of interest within the entire field of sport and recreational aviation. For example a 3-axis aeroplane pilot might opt for weight-shift control experience in trikes or powered hang gliders, or gain an understanding of rotorcraft by learning to fly ASRA gyroplanes. The only reasons for a newly-fledged pilot to do so at such an early stage of their development might be economic, or a realisation that you don't much like your current aircraft group, or you don't find the type of flying thrilling enough and would like to get into something more personally challenging, perhaps sport parachuting for example.

    Developing professionalism. But if you, the newly-fledged pilot, recognise that, up to this point, an instructor was guiding a process of learning to fly safely and now, what you are really getting with the Flight Crew Certificate — having being judged that you can do it safely — is license to continue to learn by yourself. Then you can opt to become a responsible, professional pilot. 'Professional' is not meant to imply a commercial career, rather it implies that you set high personal standards of airmanship and competency in flight — and associated operations — and accept that improvement and training is never complete, no matter how many and what type of flight hours are in your log books. This professionalism entails broadening your knowledge base so that you can set appropriate personal standards, stepping up flight discipline, acquiring additional flight skills, honing techniques and accuracy, gaining new experience and sharpening judgemental skills; perhaps undertaking a program resulting in an instructor certificate.

    Self criticism. You must evaluate your performance after each flight and identify the most poorly performed phases, determine how to improve them and then concentrate on those phases during subsequent flights until you have achieved your current required standard in that aspect of flight operation.

    In short, developing professionalism implies disciplined, continually advancing flight training, mostly personally planned and conducted but with occasional input at appropriate times from a Senior Instructor, CFI or Pilot Examiner. It does not imply that you have to become highly skilled in all aspects of flight; rather, you should be comfortably skilled in most applicable aspects and you keep raising your performance standards. We will discuss it a little more in the airmanship, flight discipline and human factors module of this guide.

    Flying, like driving a car on the public roads, is inherently risky and most unforgiving of poor discipline. One can avoid the risks by not venturing on the roads or in the sky, but if you choose to do so, then best reduce the risk by utilising defensive driving or risk management piloting techniques. The latter is integral to advanced flight training. The advanced training programs that you might undertake at a Flight Training Facility will ensure that you achieve that school's minimum requirement for safe flight, but the programs will not bring you up to your full potential — that is entirely up to you.

    Remember that in all fields of aviation, some 80% of accidents and incidents are attributed to human error. And usually not just a single act of stupidity or gross indiscipline, where both regulations and commonsense are flouted, but a series of small errors or misjudgements — not individually critical — often made by more than one person and often attributable to the applicable system.

    2. Self-training sequences
    All humankind's accumulated knowledge is published somewhere in print or electronic form so read everything that you can lay hands on that appears pertinent and authoritative — remembering, however, that your aircraft hasn't read them (nor has the atmosphere in which we fly) and responses may not be according to a particular book or an internet document – such as this one.

    There are many learning sequences that can be undertaken without assistance. Here are just a few associated with flight at slow speed, but if you are contemplating doing the following in a home-built aircraft make sure it has been through its full flight test program.
    Arm yourself with a pad and a pencil, fly to an adequate height and appropriate location and do 20 stalls in straight and level flight with varying pitch, roll and yaw attitudes and with varying power settings — remembering that stall recovery must be completed by 1500 feet agl. Note the pre-stall warning behaviour of the aircraft. What minimum easing of stick back pressure will unstall the wings? Which wing drops? How long before the nose drops? How many degrees does it drop? Can you stall it and recover without losing measurable height? What happens when you take your hands and feet off the controls?
      Ensure that your situational awareness is maintained at all times.
      Repeat the same observations with the aircraft in a balanced level turn, at varying degrees of bank, and in balanced climbing and descending turns.

    Rule of thumb: with your arm fully extended in front, the width of a finger is about two degrees, that of your palm is about 10 degrees and it is about 20 degrees between the thumb tip and the little finger tip of a spread hand.
      Repeat the same observations, at a safe height — at least 4000 feet agl — with the aircraft in a simulated descending turn to final approach and in a simulated departure climb with varying degrees of slip and skid. Gain an understanding of arrival and departure stalls.
      Repeat all the prior exercises with varying weights and cg position.
      Chart all your observations and produce a summarised reference table.
    3. Maximum performance sequences
    There are other learning sequences whose aim is to make you aware of your aircraft's capability and to help you fly accurately and smoothly. Some take you to the outer limits of the aircraft's certificated safe manoeuvring flight envelope. It is advisable that these manoeuvres are first demonstrated to you by a person skilled in their execution who can then point out to you the inaccuracies of your initial attempts. For example:
    steep power turns accurate chandelles lazy eights steep spirals. In addition, there are some ground reference manoeuvres designed to enhance ability to fly the aircraft safely and precisely while attention is divided between possible traffic, the flight path and a ground reference point — and at the same time analysing and correcting for the effect of wind:
    constant altitude/constant radius turns around a ground reference pivotal altitude turns — pylon turns and eights on pylons
    4. Tailwheel/tailskid/nosewheel endorsements
    If you learned to fly in a nosewheel configuration aircraft and you want to expand the aircraft types you can fly safely, then learning to handle tailwheel and tailskid-equipped aircraft is essential. Taildraggers can be a lot of fun but a few hours tuition in landing and ground handling technique is essential — even then you will find some taildraggers may be much more touchy than others. Conversely, a taildragger experienced pilot should get a little tuition in handling a tricycle undercarriage aircraft, but the transition in this direction is said to be easier.

    5. Flap or flaperon-equipped aircraft
    Pilots who have had no formal flap training should never attempt to operate a flap-equipped aircraft before receiving professional instruction in the use of flaps — in an aircraft having similar characteristics to the aircraft you intend to fly. The act of lowering or raising flaps results in substantial changes in aircraft attitude, trim, lift and drag — perhaps even stability. During familiarisation the aircraft is first flown flapless (if possible and practical) for a few take-off and landing circuits. Exposure to flap operation is then explored at height, with particular reference to the consequent change in attitude/airspeed combinations and the change in stalling speed, for approach speed calculations. Then take-offs, landings and go-arounds are conducted at various flap settings, wind conditions and airfield conditions. Experience in the degrees of flap and the airspeed to be used, in strong crosswind conditions, is vital.

    Some training in other systems, such as carburettor anti-icing and variable-pitch propellers, will expand competence and experience. You may find some light aircraft fitted with retractable undercarriage in which case a retractable endorsement is required.

    6. Single-seater flying
    There are many types of single-place aircraft included in the RA-Aus CAO 95.10 register. In many cases there will be just a single copy of an owner-designed and built aircraft. Flying such an aircraft is a big moment for any pilot, if only because you cannot be shown how to fly it, only be told how to fly it, and trusted to do so. However, flight in a particular aircraft should not be undertaken lightly. Most likely there will be no aircraft flight manual or pilot's operating handbook and you, personally, must ensure the aircraft is airworthy. First flights should only be undertaken from airstrips and in conditions that offer a completely adequate safety margin.

    Take heed of the placard in the cockpit that states:

    If you have not flown a single-seat ultralight with similar flight characteristics to the type you contemplate flying then it is advisable to get your first experiences under the supervision of a flight school.

    7. Low-inertia/high-drag aircraft
    Although many ultralight types would be classed as 'low-momentum' aircraft because of their high parasite drag profile and low mass, there is a significant variation in drag characteristics throughout the range. A newly certificated pilot, whose experience has been in the slippery end of the sport and recreational aircraft spectrum — the aircraft made from fibre-reinforced polymer materials — will find that the energy management characteristics of a 'fabric and tube' aircraft are substantially different. It is advisable to receive some demonstration of flight characteristics and handling techniques. This is one reason why experienced pilots with a GA licence are required to accumulate 5 RA-Aus hours, preferably in a 'draggy' aircraft, before the RA-Aus pilot certificate is approved.

    Similarly, a pilot experienced only in draggy aircraft should receive dual instruction in the flight characteristics of the more slippery aircraft before acting as pilot-in-command. This particularly applies to single-seaters constructed in fibre-reinforced polymer materials with quite high aspect ratio wings, where the closest two-seat equivalent is a sailplane.

    8. General type flying
    This adds significantly to your experience base, to the number of types in your logbooks and acts as a buffer against encroaching boredom. Before undertaking a flight in a new type, there are a few key points that should be scrupulously followed, remembering that you can't know too much about any aircraft you intend to fly:
    carefully read the pilot's operating handbook for that aircraft if there is no pilot's operating handbook, aircraft flight manual or owner's manual, ensure you receive a thorough pre-flight briefing from a competent person familiar with the aircraft ensure that valid cockpit check-lists are available for the new type, take them with you and use them completely familiarise yourself with the cockpit layout before you start the engine.
    9. Other Pilot Certificate endorsements; seaplanes and formation flying
    There are other advanced flying techniques that can only be learned from a school and instructor approved by the RAAO for these operations; for example, waterborne operations and formation flying. The former is undoubtedly the most pleasant way to operate a light aeroplane, combining flight and 'mucking around in boats' but be warned, the ground and water handling techniques for amphibious floatplanes differ substantially to those for the same aircraft equipped with a normal wheeled, shock-absorbing undercarriage; and, of course, you must also obtain the recreational boat operator licence applicable in your home State. The schedule for the floats or floating hull endorsements can be found in section 2.07 items 23 and 24 of the RA-Aus Operations Manual issue 7.

    The Seaplane Pilots Association Australia has about 450 members around Australia; membership is free. Website is www.seaplanes.org.au, download their Code of Operation.
    Formation flying means that two or more aircraft fly so close to each other that, in all manoeuvres, much the same relative position is maintained and the aircraft are seen to be in complete unison. Unless the pilots involved hold the formation endorsement, no RA-Aus aircraft can fly closer than 100 feet to another aircraft. 'Close proximity' flying is not formation flying. The photo is a formation of 16 Sea Furies with a lone Firebrand behind them, three Seafires 15s on the left and two Sea Hornets on the right. Your author remembers he was relegated to the Firebrand that day — probably thought safer for all. The schedule for the formation endorsement can be found in section 2.07 item 12 of the RA-Aus Operations Manual issue 7.
    10. STOL — short take-off and landing aircraft
    True STOL light aircraft, like the Slepcev Storch or the Zenith CH701 STOL, are excellent work vehicles and great fun to fly. However, to exploit their STOL ability these aircraft often need to be flown at the 'back end' of the power curve; i.e. very high lift coefficient (thus very high angle of attack), low velocity and high power to counter induced drag. Power is increased to fly slower, rather than decreased as in normal flight at the 'front end' of the power curve. STOL aircraft are provided with flap settings and high-lift devices that can provide a big increase in CLmax with a comparatively low increase in drag. They have a propeller that is efficient at low forward speed, a low design wing loading, and feature good stability and control at very low speeds. They can maintain steeper angles of climb and descent.

    Pilots have to be aware of those control characteristics particularly at slow speeds in turbulence. This is an area only for the trained STOL pilot, attuned to the operating environment and an individual aircraft's foibles. STOL capability may additionally be defined by the runway length needed to take-off and to land over a 15-metre high obstacle or the length of the ground roll. Utilising a very small area on the top of a hill for take-off and landing is not a capability of the average pilot. STOL techniques are not applicable to non-STOL aircraft. The photo below indicates a one-way landing area that is definitely only for experienced STOL pilots flying a tough taildragger STOL aeroplane.
    Denis Vanzella: "My first flight into Snowy Plain was a leg shaker but I've got it pretty pat now — touch wood. The one-way 'strip' is about 70 metres long with 20% slope at an elevation around 4850 feet. Best conditions are in southerly winds below 10 knots. West to north-west winds around 10 knots become vicious with a big roll off the main range that not even the Slepcev Storch can outclimb at low levels."

    Apart from STOL, there are various 'short field' and 'soft field' take-off and landing techniques applicable to every aircraft and airstrip condition, which are touched upon in Pilot Certificate training. Such techniques can be refined with advanced training.

    11. Advanced navigation
    Navigation provides an excellent field for self-instructed professionalism, particularly with the advent of low-cost global positioning system [GPS] receivers, airfield and airspace data-bases, flight planning software, moving map software, Electronic Flight Bags and online meteorological information. Prudent airmanship dictates that these advanced techniques are always regarded only as an additional aid to the basic VFR navigation techniques of pilotage and dead-reckoning.

    12. Instructor rating
    Once a recreational pilot has accumulated 100 hours of experience as pilot-in-command, a training course for the instructor rating may be undertaken. There are different requirements for persons with experience in aircraft other than ultralights. Refer to section 2.08 of the RA-Aus Operations Manual issue 7 for information about the instructor rating.

    The next module in this 'Joining sport and recreational aviation' series defines 'airmanship' and considers flight discipline and human factors training.

    1. Effective teaching strategies
    Strategy One: Using adult learning techniques
    Adults learn differently from children and have different learning needs. They come to pilot training with years of experience and successful achievements in other fields, and need to be given respect for their abilities in their own field of expertise. Instructors have to recognise that adults are goal-oriented and expect to know what they will learn and why it is important. They need to know that the instructor has a plan for their learning and will ensure they progress. They expect a goal for every lesson and they need to know how they have progressed in meeting the goal.

    Learning to fly puts some adults into a psychologically vulnerable position. The aircraft is an environment that is unfamiliar and complex. Self-esteem and ego are put on the line, and learning is hampered if the environment is not seen as supportive or safe psychologically. In learning to fly, adults have to feel comfortable in expressing confusion and misunderstandings. My best instructors made me feel psychologically safe in the environment. At no time did I hesitate in asking them to explain something again, or clear up my own misconceptions. They treated all my questions with dignity and respect. I was never made to feel incompetent or stupid.

    Strategy Two: Finding another way to explain the same concept
    Occasionally it was a struggle to wrap my brain around a particular concept. The good instructors found multiple ways of explaining the same idea. They drew pictures, they called on metaphors, they told stories, they put me in the cockpit, or they used information I already knew. The store of different ideas they called upon to help me understand seemed limitless. I remember I had difficulty working out why the ball went to the right when I put too much rudder into the left turn. Alan asked, "What happens if you put an orange on the dash board of your car and you turn sharply to the left? The orange of course rolls to the right". I will never forget that now because he found a way to connect a flying concept to something I understood. All three instructors could do that. None of them ever resorted to saying, "But I told you that yesterday!"

    Strategy Three: Limiting the cognitive load
    The capacity of our working memory is limited. We can only 'attend' to and 'process' so much information at one time. In the working memory, duration is short (about 5 to 20 seconds) and information can be lost unless you keep rehearsing it mentally — like saying a phone number over and over. Poor instructors put you in the aeroplane, get you in the air and try to tell you everything in one flight. That's like pouring water in a glass. Instead of stopping when it is full, you continue to pour but the water just runs over and is wasted. Working memory acts like that. Too much information at one time means most of it may be wasted. Additionally, if you become stressed or the information is too complex, you will have less mental space to process it. I used to go 'unconscious' when I was on short final because too much was happening, so my brain literally gave up. I could see, hear and communicate, but I didn't know what to do. The best instructors recognised the problem straight away and limited the amount of information I had to deal with. In the case of landing, Paul worked the rudders, and I worked the throttle and the stick. Gradually, more and more of the controls were relinquished to me when I was ready to deal with them. This kept me learning and conscious without overloading my brain and frustrating me.

    Strategy Four: Scaffolding student's learning
    A scaffold is a temporary support. In education terms, scaffolding is providing temporary supports for learning by 'giving information, prompts, reminders and encouragement at the right time and in the right amounts'. This is different from telling a student the answer. Students may not understand the answer. They may misunderstand the answer. They may forget the answer. They may get into the habit of waiting for the instructor to tell them the answer. Scaffolding is a defensible educational technique. It involves prompting the student to use their own brain cells to make connections and to work things out, but is given just enough assistance to help the process. I remember doing circuits in rough air conditions and worrying about my landings so much that I would forget my downwind checks. Instead of telling me to do them, Keith would ask, "What leg of the circuit are we on?" and when I answered "downwind" I would remember that I had to do my checks. In flight, if I had forgotten to turn off the fuel pump, he would ask if I had sufficient fuel. This would trigger the brain into checking everything to do with fuel and I would discover the fuel pump was on and turn it off. By using this technique, he forced me to do the thinking and problem solving rather than continually relying on him to do the thinking for me.

    Strategy Five: Focusing on priorities and key ideas
    There is a lot to learn when you begin your flight training. Everything you see, everything you touch in the cockpit, everything you are told, everything you read is important. The amount of information you must attend to and the number of tasks you must complete seem astronomical. Alan talked to me one day about priorities in flying. He made me work out what the main priority was for each stage of the flight beginning with the pre-flight. For example, the most important priorities in takeoff were oil and fuel. The most important priority on final was airspeed, and so on. This exercise was a great assistance in flying because although one tries to keep track of everything, if you have to let something go, the things you continue to look after are the priorities.

    When I transferred my training to Cooranbong, I was faced with the challenge of mastering procedures in an aerodrome with contra circuits (one side for GA, the other side for ultralights), in a CTAF with two other aerodromes and LOTS OF TRAFFIC. I was used to Temora where a busy circuit was me and one other aircraft. My first flight at Cooranbong was very stressful because I could hear masses of radio calls but I didn't know where the aircraft were or what they were saying. After the flight, Keith told me to listen for key words in the radio calls from other aircraft (that signified position) rather than try to listen to everything. He then followed up this advice by making me sit and listen to the calls on his radio and practise working out where the aircraft were. That was such a simple idea, but so effective in helping me unravel the mysteries of aircraft positions in the new CTAF.

    Now I am a pilot. I have my cross country, radio and passenger endorsements. I finally made it to this point because I had some instructors who helped me learn and did it in a way that did not destroy my dignity. I feel really pleased with myself. Alan, Paul, Keith and some of the other instructors can feel pleased with themselves too. My success is linked in a great part to their use of effective teaching strategies.

    2. Ineffective teaching strategies
    Not all of my training was helpful. Sometimes other instructors engaged in practices that frustrated my learning, and made it more difficult and time-consuming for me to attain my pilot certificate.

    Unhelpful instructor attitude
    There are many factors that affect how we as adults learn. They include our level of ability, intelligence, motivation and financial resources, as well as the skill of our instructors and their ability to analyse the problems students are having and devise ways to help the students overcome those problems. The instructor's attitude and way of communication to the student is paramount in assisting or frustrating this learning process. An instructor who has the 'if you can't learn it the first time I say it, there is something wrong with you' attitude will lose students or at least affect their attempts to learn. For example, when I began learning, I trained with a GA instructor in the US for a month. I used to fly twice a week but it was a debilitating experience. (In fact, I stopped training for eight years because he made me feel so incompetent.) When we began to practise circuits, I had trouble with the landings. As usual, I went practically unconscious on short final. I forgot ALWAYS to put the last 10% of flaps down. When I tried to land the Cessna, I would kangaroo down the runway. (I got very good at perfecting the kangaroo hop.) The instructor never tried to hide his disgust at my efforts. "That's horrible! I've told you what to do!!!", he would scream at me. Circuit after circuit I would kangaroo and he would yell. I actually knew the landings were horrible. I was desperately trying to do what he told me. His yelling at me did not EVER improve the situation. "Scan the runway, scan the runway" he would scream. Well, I didn't actually know what "scan the runway" meant. What was I supposed to be seeing, and what was I supposed to be doing? These were never explained. When we stopped, he would depart the aircraft in a huff, storm back to the office and disappear. So much for paying someone to teach me how to fly. Of course I gave up. At that time, it never occurred to me that he might share some of the responsibility for my poor performance. I just assumed that I was incapable of learning.

    Another unhelpful attitude is the "I'd rather be an airline pilot, not an instructor" attitude. The instructor in the US was definitely not interested in training me or possibly anyone else. He wanted to get his hours up so he could be a real pilot and this was one way to do it. Briefings were fast and furious and most of the content was never absorbed by me before I got into the aircraft. Consequently, I was unable to implement the information he gave me. If he noticed my mistakes, he ignored them, if he didn't he prefaced his remarks with "I TOLD you this before we left" as if TELLING someone something beforehand, out of context, and in an unsupportive environment is going to result in actually implementing the action in the aircraft. This attitude did nothing to help me learn, and did a lot of damage to my self-esteem and my perception of my own ability.

    The "you'll get it eventually" attitude is one that is most annoying to me as an educator. The number of hours I have clocked up in the log book for circuits is embarrassing now to me as a pilot. Some of the instructors I had stopped giving me instruction on landing very early in the training because they had the "if you do enough of these you will get it eventually without me saying anything" attitude. Their rationale followed along these lines. "I can't give you any visual cues for the circuit because each circuit is different, wind conditions are different, aerodromes are different. You just have to figure out if you are too high, too low, too fast, too slow, whether to put power on or not, watch your airspeed, etc. etc." So I made new mistakes every single circuit for months. I used to despair. I had so many questions and no answers. A couple of instructors sat beside me and watched me do everything wrong for circuit after circuit. Finally, I began asking for input for the WHOLE circuit. I decided I wanted input until I was ready for them to stop. I used to argue with some instructors' "you'll get it eventually" attitude.

    That may be how some pilots think. And that technique may work with some students, but certainly not all students. It certainly wasn't working with me. That is NOT how good educators think. Educators give input until they see the student doing a task correctly CONSISTENTLY, then GRADUALLY withdraw instructional scaffolding. The problem with allowing students to continue to make mistakes, is that some students perfect mistakes and consolidate their bad habits (want to see my kangaroo hop down the runway?). A better way to teach is to give LOTS of input, EVERY time until the picture becomes ingrained in the student's eye and the control input becomes connected with the picture. My last three instructors worked hard at helping me consolidate the 'picture' of the runway on downwind, base and final, and consolidate in my mind the control input needed to keep the picture right. Because they put in the information and the time, I progressed rapidly and learned to land well.

    Inadequate record keeping and preparation time
    Some of my instructors trained pilots as a full time job. Some of the instructors had other full-time employment and only trained as an interest. Some kept scrupulous records of my training and consulted the records before each flight. Some kept records, but never looked at them. Some kept no records. When I changed instructors, the records didn't come with me. That meant that the new instructor had only my log book (with sketchy information on the hours I had attempted certain skills) to make some decisions about my ability and my level of piloting skill. This amount of information was inadequate for the instructor, I realise now. As a student paying for instruction I assumed that all of my instructors would know what I had to learn and would take steps in my training to help me progress. But often they made assumptions about what I could and couldn't do that were not based in fact. When a person changes doctors, medical records are transferred to the new doctor. It would be good if detailed records followed the students who were learning to fly. Even if records did follow students, there is the problem that instructors have so little time to devote to reading them, that keeping track of students' progress can be a problem.

    There were occasions when instructors would ask me questions like, "Have you done any precautionary landing work?" or "Have you done any short-field take-off and landing work?" as we got into the aircraft. I know everyone is busy. And I do believe that students have to take some responsibility for keeping track of their own learning. But I also know that flight training is expensive and most students would expect that the instructor is keeping track of their progress. I know good educators have a plan for their students' learning. Pilot training is education and therefore the instructors need to find a few minutes before the flight to keep themselves up to speed on the individual plan for each student.

    Wrong assumptions
    The best instructors insisted that I talk out loud as I flew so that they knew what I was thinking. The best instructors also ASKED me WHY I made certain decisions so that they could discover the rationale behind my actions. Having students talk out loud or 'self-talk' can give the instructor valuable insights into novice thinking. Vygotsky, one of the most influential educational theorists of the 20th century, believed that 'self talk' helps to regulate our thinking and guide our learning. For the student, self talk can be helpful in focusing, reminding, solving problems, directing attention and forming concepts. Most instructors never asked me to think out loud. They never asked WHY I had made a decision. Perhaps they thought they knew the answer. Perhaps they were right, but perhaps they were WRONG. How can anyone work out why a student has taken a particular course of action unless they ASK them? Once the good instructors knew why I had completed a task in a certain way (that always made perfect sense to me), they were able to point out the flaws in my thinking or give me additional information that would assist my understanding.

    Another wrong assumption held by some instructors is that students will automatically understand why instructors insist on something being done in a certain way. Because it is perfectly clear to the instructor, perhaps they think it is perfectly clear to the student. This is not always the case. For example, I learned the start-up and run-up checklists by rote, but I didn't know for a long time WHY I had to do some of the tasks. I just knew they had to be done.

    Do what I say, not what I do
    This really sounds like stating the obvious, but students tend to copy the behavior and the attitude they see modelled by the teacher. Remember the old saying, "You remember 10% of what you are told, 60% of what you see, and 80 % of what you do"? I had an instructor very early in my training who told me to taxi at the speed of walking. Like so much information that is TOLD to you, its shelf-life in my brain was very brief, especially when I watched him taxi at nearly lift-off speed all morning. When I got in the aircraft, I remembered what I saw vividly and only dimly remembered what he had said. So I too taxied as fast as I could and still stay on the ground. Of course, I got chipped for that, but my reply was, "but you have done this all morning".

    Other examples include instructors not giving the mandatory radio calls, not entering the circuit properly, telling me to always put the carb heat on final, but not doing it themselves and so on. For students this is confusing and I always thought, "Why is it important that I learn to do something a certain way when a REAL pilot doesn't do it?" Of course they all had good reasons for doing something differently. However, with novice students, it is important for the instructor to maintain consistency between what they teach the student to do and what they model themselves. If the rules are changed, students have to know the circumstances in which a change in the rules can occur.

    3. Expertise in teaching
    This article is not about instructor bashing. I have had some wonderful instructors. This article is about starting and continuing a professional dialogue with instructors concerning their teaching and the learning of their students – taking into account feedback from students. It's about raising an awareness of some of the teaching strategies instructors may use that are unhelpful from, at least, one student's point of view. Instructors are good pilots, but good pilots are not necessarily good teachers. Teaching takes as much skill and as much expertise as flying. Each student is different, each set of problems that student brings is different, and each student's learning style, aptitude and intelligence is different.

    Expert teachers in any field have "elaborate systems of knowledge for understanding the problems" of their students. They recognise common problems that students encounter and have a wealth of strategies they can call upon to help students overcome learning difficulties. Expert teachers also recognise that student decisions can be based on misinformation or misunderstanding and find ways of correcting these. Expert teachers are reflective practitioners who think about student learning problems and actively engage in thinking of alternatives to assist their students. They reflect on their own teaching and assess how effective their teaching strategies are in helping students achieve learning outcomes. And they are prepared to change their teaching to ensure that students learn what they need to know. I know my best instructors not only displayed expertise in teaching but also displayed a genuine desire to improve their practice; a sure sign of a professional who takes teaching seriously.

    4. Take responsibility for your learning
    One pilot (James) told this story about his training. "When I did my pilot training, I remember I was a bit overawed by the whole idea of learning to fly. I knew absolutely nothing about flying, only knew I wanted to fly. So I took a very passive role in my training. I just went along and did what the instructor told me –nothing more. Consequently, it took me longer to catch on that it should have. If I did it again, I would probably take a more active role in my own learning."

    Pilot training is expensive and time-consuming. How long it takes to learn to fly, really depends on how long the student needs to be competent in physically handling the aircraft and understanding the theories associated with flight. For adults, training is an addition to a generally already frantically busy life. Many responsibilities compete for the time available to adults. However, there are a number of strategies that adult student pilots can employ to facilitate their learning – many take very little time and can be done mentally, while waiting for the wife or husband. Learning to be a pilot is the result, not so much of what the teacher does, but what cognitive processing is occurring in the student's mind. Student pilots should not leave all the responsibility for learning to the instructor or expect that learning is the result of an instructor pouring their expertise into a student's passive brain. Learning is an active construction of integrating new information with information we already know. The student is the only one that can do that. Remember the saying "You can lead a horse to water, but you can't make him drink"? The instructor can give a student all the good oil in the world, but the student has to actively engage in making sense of the information.

    This article forwards a number of strategies that may help student pilots to facilitate their own learning. These strategies were solicited in interviews with pilots and instructors, and have a theoretical basis in educational learning research. They have been organised into three sections of actions students can take: before the flight, during the instructional time and after the flight. They all follow the same theme, "Take Responsibility for your Learning".

    Pre-flight preparation
    Flying is a combination of physical and mental development and understanding. The student can help himself by reading the theoretical aspects of flight that will be the focus of the next lesson. While reading, the student should note any questions that occur. These questions can then be addressed by the instructor in the course of the lesson. When learning new information, it is not uncommon for individuals to have to revisit some concepts more than once for them to make sense. Reading the theory beforehand helps this process of learning because it establishes a cognitive framework that can be reinforced through instruction and implementation.

    There are other kinds of mental preparation that students can employ to prepare them for their flight besides reading the theory. One technique that some find useful is visualisation. If a student is going to do circuits, for example, she or he can fly the circuits in their mind, going through all the checks, motions and radio calls that they will be required to do in the aircraft on each leg of the circuit. If the student is going on a navigation exercise, she or he can fly the nav several times at home in a chair, looking at the chart, practising calls and changes of heading, and so on. Visualisation of a process or procedure can help students to implement them more effectively and efficiently when faced with the real thing.

    Another useful technique is physical preparation. One instructor suggested that students who have difficulty sorting out their circuit directions could practise them at home by drawing a circuit on the garage floor and walking the various legs of the circuit until the crosswind, downwind, base and final legs were clear in their mind. This technique has also been used for learning how to position the aircraft nose relative to the wind on different legs of the circuit. This represents a kind of kinaesthetic rehearsal — a technique that sportsmen use to 'practise' various aspects of their sport when they are not on the field. This technique can also be used early on in training to become familiar with the position of the controls and avionics while sitting in a parked aircraft.

    Sitting in the stationary aircraft and rehearsing emergency procedures for engine outs, engine fires and electrical faults can also be a good preparation for the real thing when students say the process and physically touch the controls and switches that need to be turned off or used. Writing down the terminology and the order for making radio calls and practising them at home is another good way for novices to learn to give their radio calls before they get to the aerodrome.

    There is another kind of physical preparation that is important before the lesson. This falls into the category of "Am I fit to fly today?" One instructor told the story about a training session that ended up being very ordinary because the student had played Rugby Union the day before and was physically not up to the rigours of flight training. Unless students are alert and ready for the flight physically, they may not get much out of that particular lesson. The classic example is the person who had a big Friday night at the pub and then arrives at 8 am the next day to fly ? not a pretty sight. Self-motivation and study to prepare for the lesson are essential, but having your body ready is also very important.

    Instructors do not always have the time in the lesson to explain all areas of the syllabus in great detail. Information on engines, propellers and weather conditions is important. Student pilots should show some initiative and do some reading in these areas to supplement the actual learning that occurs when they are in the aircraft.

    A final useful technique is for students to make a list of learning priorities for their own lessons. This helps to focus attention and mental energy, and helps students to actively engage in those aspects of the lesson that contribute to their priorities.

    Instructional time
    Being a good pilot requires knowledge not only flying but also a thorough knowledge of the aircraft, its capabilities, limits and procedures for handling on the ground as well as in the air. It's a good idea to arrive at the aerodrome early and read the aircraft manual so you are familiar with the technical specifications unique to that aircraft. It is also a good idea to assist the instructor in activities like refuelling, moving the aircraft and finding out where to do engine start-up procedures.

    Flying is such fun and the temptation is to enjoy every minute in the cockpit at the expense of doing the work well. One of the instructors said that students need to understand that learning to fly is 'work', not 'play'. Students need to keep their mind on the tasks at hand and actively engage in establishing and improving their skills. Their 'head' needs to be in the cockpit and not on what happened last night or will happen tonight. The operation of the aircraft requires the full attention of the novice aviator.

    A good technique to help focus attention to tasks and problem-solve is 'self-talk'. This allows thinking to be clarified by the instructor. Talking out loud also clarifies thinking for the student. Students should also be quick to ask the instructor for advice or input when they are unsure of a procedure or an instruction.

    Flying regularly at short intervals is more useful than flying once in a while or at long intervals. There is a certain amount of re-learning that has to occur unless the student pilot is preparing for flights by engaging in visualisation or other mental and physical preparation between flights.

    After the flight
    Student pilots need to be proactive in searching out the information they need and clarifying the information they don't understand. Instructors can assume that students are following their explanations unless the student gives feedback to the contrary. Student pilots should ask questions about flying, about training, about the expectations of the instructor, about the readings they need to do and about their progress.

    Students can also engage in reflective thinking about the flight. In fact, flying the lesson again in their mind can help them to realise what actions they took that resulted in various outcomes. They can examine their actions and the thinking they engaged in when performing those actions to determine what they would change or vary the next time they fly.

    Learning to fly takes a lot of physical and mental energy and effort. Even though most students live busy lives with spare time at a premium, time put aside for preparation is well worth it. The more mental and physical preparation a student engages in before, during and after the flight, the more they will achieve. Students who take responsibility for their learning will reap the rewards and maximise their training.

    Section 1. Lieb, S. (2000). Principles of adult learning http://www.hcc.hawaii.edu/intranet/committees/FacDevCom/guidebk/teachtip/adults-
    Sections 2-4 Woolfolk, A. (2004). Educational psychology 9th edition, Sydney: Allyn and Bacon

    The next module in this 'Joining sport and recreational aviation' series discusses advanced flight training for power-driven, 3-axis control aeroplanes.

    The RA-Aus flight training organisation
    The RA-Aus Operations Manager is responsible to the Chief Executive Officer, the member-elected RA-Aus Board, and the Civil Aviation Safety Authority, for the maintenance of a continued high level of safe training practices and methods, general flying and safety standards and pilot competency throughout RA-Aus. There may be Assistant Operations Managers taking some of the load for a particular area.

    To implement these duties and responsibilities, the Operations Manager approves and initially appoints suitably qualified Chief Flying Instructors [CFIs] as Pilot Examiners [PEs], who then undertake that responsibility for maintaining the high level of ultralight training practice and the general flying standards usually within a particular region. Pilot Examiners carry out the following routine tasks: conduct ground and flight examinations for issue or renewal of Senior Instructor and Instructor ratings conduct ground and flight examinations for issue or renewal of Chief Flying Instructor approvals or Pilot Examiner Certificates conduct training and refresher courses for CFIs and PEs, or candidates for those appointments and monitor, on request from the Operations Manager, the training standards and practices of specified flight training facilities [FTFs]. If approved by the Operations Manager, a PE (and a CFI or Senior Instructor) may also conduct ground and flight training courses for instructor rating candidates.

    Regional Operations Coordinators [ROCs] are also appointed to assist the Operations Manager. An ROC has all the duties and responsibilities of a Pilot Examiner and additional responsibilities, which are specified in section 1.04 of the RA-Aus Operations Manual issue 7. See the listing of ROCs (PDF document).  
    Lee Ungermann, then RA-Aus Operations Manager, lifting off from former CEO Paul Middleton's Dog Plain International.
    The aircraft is Lee's Australian LightWing. (photo - Paul Middleton)

    RA-Aus flight training facilities [FTFs]
    There are about 180 approved FTFs currently operating at about 200 locations throughout Australia; all have a minimum training capability up to and including the cross country, passenger and radio endorsements. See the flight training facility location list with telephone contacts. There are other trike schools approved by the Hang Gliding Federation of Australia.

    Flight training personnel
    There are around 300 members whose Pilot Certificate is endorsed with a currently valid senior instructor rating. Abot 60% of the senior instructors also hold an RA-Aus document of approval to act as the Chief Flying Instructor [CFI] of a particular FTF or FTFs, thereby being held responsible for the operation, administration and control of the nominated FTFs.

    Note: in USA aviation the 'CFI' initialism is the shortened form of 'Certificated Flight Instructor' or 'Certified Flight Instructor' and describes every flight instructor rather than the senior instructor responsible for flight operations, administration and control at a particular flight school.

    Various document listings of the personnel associated with flight training are also available. The following provide names and contact means by location.
    • Senior Instructors with current Chief Flying Instructor role.
    • Other Senior Instructors
    • Instructors

    The clubs associated with RA-Aus members
    About 35% of members belong to one, or more, of the 100 or so RA-Aus recreational aviation members clubs. The primary role of those clubs is to provide the social and competitive impetus for the development of recreational and sport aviation, and of their pilots. A second, but very important, role is supportive — the training, nurturing and care of less experienced pilots. Unlike the Gliding Federation of Australia clubs, the RA-Aus member clubs have no authoritative role in the administration of recreational aviation.

    Some RA-Aus flight training facilities have an associated club — or a close association with a co-located club. The clubs usually provide a range of services to members, from advice and assistance in all aspects of flying and owning a recreational and sport aircraft, to hangarage and perhaps hiring of club owned aircraft — for both training and pleasure. About 50% of the clubs are themselves 'affiliated members' of the RA-Aus. Generally most club members would also be RA-Aus members.

    Some RA-Aus clubs tend to specialise in a particular category of aircraft, i.e. 3-axis aeroplanes, weight-shift control trikes or powered parachutes. Conversely, others include a wider range of interests, including general aviation aircraft and pilots. Other clubs may focus on particular interests, for example, constructing aircraft from commercial kits.

    Clubs may provide on-site accommodation for non-local members, varying from individual rooms, or bunkhouse, to caravan or camping. Membership may entail a small joining fee and an annual fee. Some clubs may offer family membership to cover the non-flying family members. Social activities might include regular fly-ins, flyaways and handicap flying competitions. The hangar barbecue tends to be a regular monthly event at which visitors — and potential members — are always welcome.

    See the RA-Aus website for their list of affiliated clubs and contact information.

    The next module in this 'Joining sport and recreational aviation' series documents a students viewpoint of the learning to fly process.

    1. Medical, health and clothing
    The basic medical requirement is that your health meets the requirements necessary to hold a car driver's licence. This significant concession allows people to fly who would otherwise be grounded in General Aviation. RA-Aus flight instructors, however, must hold a valid General Aviation pilot's medical certificate.

    General health considerations are basically commonsense. Do not fly when under the influence of alcohol or drugs. Some medications present no problem but consult your doctor if in doubt. You should avoid flying when taking prescription drugs that affect your orientation, vision or alertness, for example some antihistamines cause drowsiness. If you wear bifocal glasses, or have just changed your glasses, it may be wise to check that your vision is OK. This is not particularly visual acuity but more about any impairment to perception of height (and changing height) near the ground.

    At our own school, clothing is not too much of a problem. During the summer, slacks and shirt sleeves are normally OK with possibly a light pullover or jacket early in the morning. In winter, a warmer jacket and light gloves may be required early on. Communication headsets are provided by the school. However, note that clothing is dependent on the ultralight type. Very exposed cockpits require suitable clothing in the form of padded flying suits, very warm footwear and gloves, plus helmets. Our school's aeroplanes have semi or fully enclosed cockpits so there is less of a problem, plus Queensland is generally warm all year around.

    2. What are your goals?
    You should spend a little time reflecting on why you want to learn to fly or convert to ultralight flying. This is important for practical reasons I will come to, but overall the objectives people start out with often change after they have some practical experience.

    Having a reasonable idea of what you want to do, and why you want to do it, should have an important bearing on the school you choose for your training. In addition, the following section briefly discusses different types of ultralights — and there are many. This should also influence your decision on what type you train in.

    Finally, we strongly suggest that you do not buy an aeroplane before you have ample practical experience by which your personal goals can firm up a little.

    3. What type of recreational aeroplane?
    A little time will be spent on this one because your personal conception of what a recreational aeroplane is may be a long way removed from that which any particular school has to offer for training. If you do not train on something matching what you want to eventually do, then you could waste a great deal of money, be generally unhappy in training and so not learn as well as you might. You may also find you are up for considerable extra training to reach your personal target.

    Recreational aeroplanes fall into two main categories — '3-axis control' (normal aeroplane control with stick, ailerons and rudder) and 'weight-shift control' (where the aeroplane is steered as a result of moving the pilot's weight relative to the wing).

    In the latter case there are two main recreational aeroplane categories — the powered hang glider (usually known as 'trikes') and the powered parachute (or Aerochute). In both cases the crew pod and engine are suspended below a wing or canopy. These are generally rather slow and exposed aeroplanes and are also a bit physical in how they are controlled.

    In the 3-axis area there are again broadly two sections. We may term one 'traditional style' ultralights which by, nature, are high drag and low inertia or low momentum aeroplanes. The other we may term 'de-facto GA' and these tend to be larger, heavier, cleaner and more expensive.

    In three short paragraphs I have given you five major choices — for you will now face what trainers are available to learn to fly on at the schools you can reach. There is not much point learning to fly on a fast, glass fibre Jabiru 3-axis when your leanings are towards the trike style of flying — the controls work the other way around for a start. At the same time, if your concept of a recreational aeroplane is a Jabiru, then you are going to be less than happy with meeting a trike. Just because a school is an RA-Aus school does not mean it has the aeroplane type that matches your personal goals.

    Generally, there are trainers about for the various main categories. There are fewer trike schools than 3-axis and equally there are very few powered parachute schools. The majority of people go for 3-axis and there are a couple of wrinkles here to consider. The considerations again depend on your personal goals.

    If you are aiming at low-cost, simple, local flying then you need a 'traditional' style ultralight trainer to prepare you for this. If you train on something more slippery and heavier, then you may need additional training to prepare you for what you later buy. If you train on a traditional trainer with your eventual sights on something more up the ladder, then your conversion to the larger and faster machines is far easier.

    If your intention is to get something relatively large or fast, or just continue hiring the school aeroplane after you have achieved the pilot Certificate, then you should look for schools that provide the class of aeroplane you are interested in.

    You should also be aware that 3-axis aeroplanesaeroplane, as a group, are divided into two quite separate additional categories, no matter their price, size, etc. — this is nosewheel and tailwheel aeroplane. In the former, the aeroplane stands on the ground in a level attitude with its weight supported by a largish nosewheel and two mainwheels further aft. The tailwheel (or 'taildragger') has two main wheels well forward, a light tailwheel, and sits on the ground in a tail-down attitude.

    This may not seem of much consequence, but it is. The nosewheel aeroplane is considerably easier to land and to handle on the ground. The taildraggers can be a handful without the correct training. If you learn on a taildragger, you can convert straight into a nosewheel. If you learn on a nosewheel, you may require several hours more training for a safe conversion to a taildragger. A good parallel is in driving. If you learn on an automatic car you will have trouble adjusting to a manual gear change car and will require some practice. If you learn on a manual, you can get straight into an automatic.

    At our school we have deliberately aimed for the middle ground. The tailwheel aeroplanesaeroplane we operate are the most exacting trainers in the RA-Aus training fleet. They are not easy but we have a lot of ways to enable you to tame them in a similar time to anything else.

    However, if you learn in our taildraggers you are pretty much equipped for anything. You can move down into the lower weight and simpler aeroplanesaeroplane, or up in performance to the larger, heavier and more expensive types. Either way, your training will be totally valid, and later when your personal goals may change, our training will support your new decision.

    4. The trial instructional flight
    If I have given you too much information and you are now unsure of exactly what you want to do and what you want to do it in, then there are practical means of making your mind up.

    Visit a couple of schools, see what aeroplane they have and try an air experience or trial instructional flight [TIF]. There is free temporary membership of the RA-Aus available for TIFs so there is no outlay other than the flight cost. However, be warned; the TIF can be translated as trial introductory flight, which is little more than a sampling joy ride. At our school we give you a 20 minute pre-flight briefing and 25 minutes in the air, most of which you will spend on the controls. Our intent is to enable you to sample our instruction as much as our aeroplane and airfield.

    When you start training you may have three hours flight instruction before you make a decision to continue. At that point you must join RA-Aus or give it away.

    Your actual training will depend on three main elements: (a) what you want and if local schools can supply the aeroplane category; (b) how much you can afford; and (c) how much time you have.

    5. Some practical hints on training
    The following is written by a person with 35 years experience of recreational flying training instruction in three different aviation disciplines. You would do well to give the following words more than a passing glance.

    You basically have three choices: (a) you will train via 'casual' visit to a local school (perhaps visit once or twice per week or fortnight); (b) if you cannot get what you want locally you will go somewhere else, perhaps a distance away, and stay for a period of intensive training (maybe one, two or three weeks); and (c) you strike a compromise and perhaps start with a short course for basics, continue with casual training locally, then finish off with a further short course.

    Do not fall into the trap of just dividing the minimum 20 hours flying training by days available. You have fatigue levels and in our experience you will not withstand much more than 2 hours intensive basic flying training per day in conjunction with the ground lectures we give and the homework we also give. You can certainly do more, but it will not be value for money training — only flying time. The bottom line is not how many hours you have done but the competency standard for what you are doing — how well you are doing it. It is the competency standard that has to be reached, not just the minimum hours, and you will have to do as many hours as that takes — without adding non-productive hours to it.

    You should also think of the 'two steps forward one step back' if you are casual training. Regularity of attendance is critical to your training progress. This makes you more vulnerable to weather. If you lose two consecutive weeks due to bad weather on your 'flying day' then it will actually be nearly a month between flights. Flexibility in attendance is important when casual flying to keep you current and progressing.

    On courses you should also think of the 'skills most quickly learnt are those most quickly lost' aspect. You should structure your finances so when you return from a course you can continue keeping in regular flying practice. Bear in mind that an aeroplane is not a car — you cannot pull over and have a think about things, once you go then you have to complete a flight and the consequent landing, which requires you to be in practice. Holding a pilot's certificate is only a demonstration of competence reached, not an assurance that you can have a big lay-off and be as good as you were when you were flying every day, at least not until you have a great deal of experience.

    Another important factor in your flying training — in terms of both value for money and your eventual standard — is support training. Most people do not realise that maybe 90% of flying instruction happens on the ground where there is time to ensure your understanding and preparation for the intensive bursts of time you actually spend in the air. It is essential that your flying is fully supported by lectures, and pre-flight and post-flight briefings. In turn, these should be conjoined with reference and study material so you can learn and revise at your own pace in your own time.

    Weather conditions also have a large bearing on value for money and progress. Recreational aeroplanes are light so they get bounced around in turbulence. When you are coming to terms with controlling an aeroplane you need to be able to clearly see the results of your inputs without the atmosphere obscuring the situation by making the aeroplane do the opposite to what you are attempting.

    A good pointer to how well any school actually understands and controls training is the length of each flight lesson. The majority of human beings have learning limitations, which result in a marked slow-down of absorption, and an increase in error, after about 35 minutes engaged with the current exercise. You obtain far more value by getting out for a break after 35–40 minutes in your basic training and then having another session.

    At our school we offer both casual and course flying, and tailor the training to individual requirements — you will only get what you need. We use powerful conceptual instruction methods in conjunction with lectures, briefings and the school's integrated briefing note series. Our airfield is large but the design ensures you do not waste heaps of time taxiing and it is normally quiet, so you can get on with repeat circuit work without being slowed down by other traffic.

    6. Choosing a school
    The main problem any new student faces is that, by definition, they will know very little about flying and particularly the mechanics of flying training. This does not put you in a very good position to make decisions when you are just about to invest a fair amount of your money.

    As students have little choice, assumptions tend to be made. The most common one is that all schools and instructors are fundamentally the same — therefore a choice can be made (for example) based on the most attractive price, whereas actual value for money should be the determining factor. Certainly all schools have to meet the stipulated standard, but how they do this is very much up to them.

    The foregoing notes will have given you some ideas on key areas that will affect the value of your training in standards, money and human terms. We will now give you some general advice on how you can employ that information.

    Your most valuable information source is word-of-mouth referral from people who have similar goals and outlooks to yourself. They have been 'hands on' and will know how the interface with the school felt like subjectively as well as objectively.

    If you do not have such an information source then you will have to make decisions for yourself. The first step is finding a school that has an aeroplane type suitable to your intentions and which has a location to meet your travel and time needs.

    You now need to get a 'feel' for how the school will work for you — is it a bit cold and commercial, or friendly and 'clubby', or somewhere between. You could take a TIF to try them out, but also spend some time watching the operation and studying the general activity on the airfield. See how they handle their students and talk to those students yourself to get their impressions.

    You may not be able to do much assessment by visit if you intend travelling some distance to a course. In this case, an important factor is to assess how much the school is trying to inform you and help you versus how much 'selling the product takes precedence'. In our case we are rather blunt. We would sooner take the time to give you information, to make valid decisions on, than have you here for our product when you do not actually need it. That would only waste your time and ours — better to sort it out now.

    In addition to the above you should be given a reasonable idea of what is going to happen to you. At our school you will receive one-on-one training with the same instructor and possibly flying with another for just isolated exercises for a change of pace. You will either be on your own or with one other person, usually one of our casual students who will be different on a day-to-day basis.

    We will require you to fly early mornings (6.00 am) and we usually operate (on average) until around midday, depending on the time of year. When you arrive we will sell you a copy of the school's briefing notes and then put you in a co-ordinated program of lectures, briefings, flying and then homework using the notes for revision or initial penetration of new exercises. These programs are individually designed for your particular needs as a person in conjunction with whatever stage you may have reached.

    We seldom fly late in the day partly from fatigue reasons from the long day (you will get tired and we have to watch this), and mainly because on most days we have a brisk sea breeze come in just as the convective turbulence is beginning to ease. We will not fly you in the turbulent middle of the day until you are virtually at Certificate stage and have confidence in how the aeroplane responds to your own inputs and can therefore work out how the turbulence is affecting the machine. Note, however, that some inland schools (approximately 50 miles or more from the coast) do not get sea breezes, and late afternoon and evening can provide good training conditions.

    Another important point in assessing a course is the mundane matters like toilets, showers, food and a bed, and the distance away some or all of these may be. A lot of schools leave this entirely to the student. So do we to an extent, but we can steer you in the right direction and make arrangements for you.

    7. Conversions from general aviation aeroplanes or from GFA sailplanes
    Please note that some general aviation pilots become confused about RA-Aus aeroplanes. The PPL allows flight in aircraft below 5000 kg but this means a VH-registered aircraft under the CASA control system. The licence does not allow you to go and fly a balloon or glider, neither does it cover an RA-Aus aeroplane. The recreational aeroplane is controlled by the RA-Aus system, carries RA-Aus registration and has its own legal ordinance. Part of that ordinance requires you to be an RA-Aus member and carry an RA-Aus Pilot Certificate to fly an RA-Aus registered aeroplane.

    If you have prior gliding or General Aviation experience to the extent of 20 hours of which 5 hours are as pilot in command, then the minimum requirement becomes 5 hours experience on RA-Aus aeroplanes of which 1 hour must be as pilot in command. You must also satisfy an RA-Aus Chief Flying Instructor that you are conversant with the flying training syllabus, particularly the handling of high-drag, low-inertia aeroplanes.

    If you already carry radio operator and/or cross country endorsements then RA-Aus will accept these without further training or testing if they are from a recognised source.
    ... Tony Hayes, CFI

    The next module in this 'Joining sport and recreational aviation' series is is an outline of the RA-Aus flight training organisation, facilities and the clubs associated with RA-Aus members.

    1. What is an air experience or trial instructional flight?
    In essence, an air experience flight is a trial instructional flight [TIF], a way of sampling flight training without making any commitment to joining the movement or continuing with sport and recreational flying. Please be aware that a TIF is not a so-called 'joy flight' — although you will enjoy it. Our world of sport and recreational aviation is not permitted to fly for hire or reward, except payment in return for flying training services; therefore 'joy flights' are strictly a no-no! To obtain maximum benefit from a trial instructional flight, invest a few minutes reading the following.
    RA-Aus flying training can only be provided by an approved flight training facility [FTF], which has to meet certain operating standards at regular inspections. The flying is provided in a certified and registered, fully dual-controlled, approved training aircraft — 3-axis control aeroplane, weight-shift control trike or a powered parachute — maintained by the holder of a level 2 maintenance authority. The training is given by authorised flying instructors, who themselves are checked regularly.
    Do not be put off by all the approvals and controls — they are there to ensure safety and quality of participation. You are not heading for something that seems like a QANTAS appraisal for new staff. What comes out the other end in our environment is a friendly, maybe even apparently 'laid-back', recreational flying ambience you will easily fit into and become part of. Sure, the backbone is there, but it remains under the surface.
    So if we cannot give you a 'joy flight' we can give you something better, from which you will obtain a much greater insight and enjoyment — the TIF.
    2. How does the TIF work?
    You do have to be an RA-Aus member to participate but this can be at no initial cost to yourself. The FTFs have a book of simple dockets that can be filled out on the spot — you are then an RA-Aus member for a 28-day trial period.
    There are a number of components to a good quality TIF — it is not a simple case of just hop in and have a go! The objective is to give you a good and fair sampling of what recreational flying feels like, plus an insight into the flight training process.
    The TIF follows the same sequence as a normal instructional flight:
    Pre-flight briefing
    You will usually spend a little time in a classroom being convinced, in simple non-technical terms, that you do not have to be some kind of supernatural being to be a pilot and that an RA-Aus aircraft is much the same as any other flying machine. The aircraft essentially works all by itself and you are there to control it — make it take you where you want to go. It is just another vehicle to learn to control; like a push bike, car or boat.
    Aircraft pre-flight inspection
    You will be shown around the aircraft and while it will be clear that the machine is inspected prior to flight, you will not be involved in any technicality at this stage. You will be shown how to get in, adjust the seat so you are in optimum control position and how to strap in. The cockpit equipment will be briefly outlined to you, as well as the actions to be taken in an in-flight emergency. Much like the pre-flight briefing by the cabin crew when flying as a QANTAS passenger.
    Flight procedures
    Your flight will be in the vicinity of the airfield and for usually about 25 minutes total. During the flight you will be exposed to the sensation of being both in a very light aircraft and aloft in a very personal form of aircraft. You will be shown the airfield from the air, the local scenery and points to orientate yourself by. You will spend more than 50% of the time with control of the aircraft in your hands, under the guidance of the instructor.
    No need to be alarmed about this — it is a simple matter of being shown how to raise and lower the nose, plus bank and level the wings. This will give you a 'feel' for the machine in its natural environment and you will find it surprisingly easy. You will only be asked to do things the instructor knows you can easily accomplish and absorb.
    Nothing odd or abrupt will happen. Your instructor will give you advance notice if the engine note is going to change or if the aircraft is going to change attitude, plus what it will be doing. You will not be subjected to aerobatics or unusual attitudes — you are primarily orientated to a two-dimensional world and we make the transition into the three-dimensional world of flight understandable, progressive and comfortable.
    Post-flight debriefing
    Your instructor will answer any questions you have and underline a few of the main points of the exercise in which you have just participated. Your options on where you go from there will be explained to you, partly verbally and partly with literature the FTF provides for new members. Then it is your decision. There is very little 'hard selling' in Recreational Aviation — nobody should be pressured into learning to fly — you should WANT to, deep down within yourself.
    If you are still unsure then you can obtain three hours actual flying training from the school, within the 28-day trial period, before committing yourself to full membership of RA-Aus and applying for the RA-Aus Student Pilot Certificate. If you wish, you can download the "Application for membership — Student Pilot" form from the RA-Aus applications page.
    3. How do I get best value from a TIF?
    TIFs are not expensive but you can get additional value from them if you plan your TIF and you know what to look for. The apparent quality of the flight school, the instructors and the airfield will figure in your decision on where you want to fly, what you want to fly, and who you want to fly with. The TIF gives you a look at all of these and assists your decision.
    Start asking yourself questions. The TIF will give you a flight, but what do you want to do with your intended future flying? Just 'fly a recreational aircraft' is not a sufficient answer — that is easy enough to arrange — but there are some things of which you need to be aware.
    4. RA-Aus aircraft types
    We have a number of quite different aircraft categories (which we touched on in the previous module) and you may already have a preconceived idea of what a recreational aircraft is supposed to be. Make sure you go for a TIF in a type that matches your personal goals — even if they are not yet fully formed.
    Some of your considerations are not just what you want the aircraft to do, but also the initial and on-going costs of possession and maintenance (in Recreational Aviation you will be able to service your own machine for personal use — will the complexity be too much for you?); and will your goals outgrow the machine? Although we have looked at the types of RA-Aus aircraft in the preceding module, it may help to reiterate a little.
    Three-axis control aeroplanes
    For fixed-wing aircraft with conventional flight controls, refer to the relevant groundschool flight theory section. The three-axis aircraft have two landing gear configurations — nosewheel or tailwheel. The latter is a little harder to learn on but far more suited for rougher operating strips. The nosewheel aircraft are easier to take-off and land, but if you gain your RA-Aus Pilot Certificate solely in such aircraft then you will need a further five hours or so training to then convert to the tailwheel layout.
    Traditional ultralights
    These mainly have a tubular metal main structure and fabric covering with three-axis control. They are often with open or semi-open cockpits. The usual operating range is up to 200 nautical miles (360 km) and cruising speeds of 55 to 65 knots (100 to 120 km/h). Usually they have two-stroke motors, but four-strokes are being increasingly introduced.
    Newer types
    These are heavier, faster and more expensive than the traditional low-momentum ultralights. Often they can be optionally registered with the Civil Aviation Safety Authority as a general aviation aircraft, or with RA-Aus as a sport and recreational aviation aircraft. They usually have fully enclosed cockpits. Range is around 250 to 500 nm and cruising speeds are 70 to 120 knots. Generally they have 80–100 hp, four-cylinder, four-stroke Jabiru or Rotax engines. (Cheetah, Jabiru J120, Lightwing.)
    Weight-shift control
    This means an aircraft controlled primarily by shifting the pilot's weight in relation to the wing attachment point — these include RA-Aus trikes and some powered parachutes and also the HGFA hang gliders. See 'Hang glider and 'trike' wings and carriages' in the groundschool flight theory section.
    These look like a large 'powered hang glider' but are now in a class of their own. They comprise an open cockpit pod suspended below a 'Dickenson' wing (no tail unit) and are controlled by a 'trapeze bar' in front of the pilot. Range is up to 300 nm and cruising speeds are around 50 to 70 knots. They have two-stroke and Rotax 912 four-stroke engines, see the Airborne website.
    Parawing control - Powered parachutes
    This is a large, steerable parachute canopy with an open, two-place, 3-wheel carriage below it, suspended by shroud lines and steered by control lines. Power is usually a Rotax 65 hp two-stroke engine. Range is about 60 nm and they have a constant speed around 25–30 knots. Refer to the relevant groundschool flight theory section and see the Aerochute website.
    There is another version of the powered parachute, the Group F foot-launched, powered parachute or powered paraglider. The power pack is strapped to the pilot's back. Obviously this has to be a single-person vehicle and no dual control instruction can be given; such vehicles are only suitable for an experienced powered parachutist.
    5. How do I arrange a TIF?
    Having made a decision (no matter how broad) on where you think you want to go in flying, then study the complete list of FTFs. Pick a school and give them a bell. It is better to book rather than just turn up. If you are unsure of whether you want to progress with a particular school, or on a particular type of ultralight, then take a few TIFs at different places and/or on different types — you are not wasting money, you are probably saving it — plus broadening your experience base.
    The most important person in the world of aviation is not the most experienced instructor — it is the rawest beginner, because the future of aviation will be partly in your hands. Unfortunately the beginner is by definition the least equipped to make decisions on what to do. We trust the words above will help you make those decisions.
    Tony Hayes — inaugural holder of the RA-Aus Meritorious Service Award.
    The next module in this 'Joining sport and recreational aviation' series is another article authored by the late Tony Hayes about getting flying training underway.

    1. Student entry conditions
    A student cannot fly as pilot-in-command of an RA-Aus aircraft (i.e. fly solo) until she/he has attained the age of 15* and until a Student Pilot Certificate is issued. Up to three hours dual instruction can be undertaken before applying for a Student Pilot Certificate and a further six hours dual instruction may be flown while waiting for the document. However, an intending student can apply for RA-Aus membership and issue of a Student Pilot Certificate, before selecting a particular flight school, by downloading the form Application for membership – Student Pilot Certificate from the RA-Aus website and returning it to the RA-Aus office. If the applicant is under 18 years of age a parent must also sign the application.

    *Note: thus a person would have to be at least 14 years old before it is practicable to commence flight training; in all Australian states the minimum age for a learning to drive permit is 16.

    Generally, as long as you are in reasonable physical and mental condition — equivalent to that needed to hold (and maintain) an Australian private vehicle driver licence — you can become a member of a sport and recreational aviation association and learn to fly an Australian sport and recreational aircraft, just for the fun of it, and at your own pace and convenience. Your medical fitness does not need to be confirmed by a designated aviation medical examiner, nor do you need a medical certificate from your own general practitioner; but you must sign a declaration that your medical fitness is at least equivalent to that needed for the driver licence. For more information on the physical condition required for the private vehicle driver licence see 'Assessing fitness to drive'.

    A student pilot must possess a RA-Aus Operations Manual (which will be issued automatically by RA-Aus on joining) and a log book, and it is recommended that a study manual is also purchased. There are a number of titles available or you can use the tutorials on this website. You may also wish to purchase maps and other reference materials. When you start training, the school should issue you with a training package that contains flight notes produced by the school including a Pilot's Operating Handbook* or aircraft Flight Manual for the training aircraft and a study manual.

    *Note: a Pilot's Operating Handbook is a basic form of aircraft Flight Manual established by the United States General Aviation Manufacturer's Association in 1975.

    The RA-Aus Operations Manager may refuse to accept an application for a Student Pilot Certificate or a Pilot Certificate if it is known that the applicant has a history of aviation regulation contravention or flying activities that might bring the good name of RA-Aus and its members into disrepute.

    2. Ground and flight programs at flight training facilities All forms of flight are potentially hazardous, but the skills of safe flight can be readily mastered by anyone who has the necessary enthusiasm and motivation, and consequently willing to devote some effort to it. Remember the regulations expect that you are an 'informed participant'; being a person aware of the risks involved in a particular form of sport and recreational aviation and willing to accept those risks.
    The training programs at flight training facilities [FTFs] comprise a ground study program and an in-flight program, but much of the ground study program is usually done in your own time, under direction from your instructor. The principles learned on the ground are assimilated in the flight program so that you, the student pilot, should always be comfortably aware of the consequences of each of your actions, or inactions. Each in-flight lesson entails flight time of about 45 minutes plus pre-flight and post-flight briefings; thus the total time at the FTF for each flying lesson will be about two hours. Flight training will be conducted in both the airfield circuit area and a local training area designated by the school; except if a cross country navigation exercise [navex] is involved. The flight time for a longer navex may be 90 minutes or more. You can of course opt for two flying lessons in each day; i.e. a full time schedule. More than two in-flight lessons in one day is probably unproductive, as are lesson durations that exceed 45 minutes — excepting an advanced navex.

    3. Outline of the flight training program
    The Australian Civil Aviation Safety Authority [CASA] Flight Instructor Manual issue 2 (December 2006) is available in PDF format (89 pages) and although it is intended primarily for flight instructors, a student will find it is well worth studying. The manual is written for 3-axis fixed wing aeroplanes but the programs for weight-shift trikes and powered parachutes are similar. The exercise sequence outlined in the CASA manual is as follows: Familiarisation with the aeroplane and air experience Preparation for flight Taxiing Operation of controls Straight and level flight Climbing Descending Turning Stalling Sideslipping Take-off Approach and landing Spin prevention and spiral dives First solo Emergency and special procedures Pilot navigation Instrument flying Night flying The RA-Aus syllabus is similar, though the last two items covering instrument flying and night flying are not included in any sport and recreational flight training program because such aircraft are prohibited to fly in meteorological conditions that mandate flight by instruments only, nor may they be flown after last light or before first light.

    The ground study program, though broad-ranging, does not require any particular educational qualification except for reasonable proficiency in spoken and written English. It covers — in general terms — the theory of flight, the atmosphere and aviation meteorology, aircraft instruments, engine handling, radio communication procedures, flight planning and navigation, air law and basic (level 1) aircraft maintenance plus coping with emergencies.

    The diagram below shows an indication of the practical and exam components required to attain the Pilot Certificate. Note that the hours shown represent the legal minimum required. More often than not, most student pilots will take longer than this to achieve competency before they can first fly solo, and before they can attempt the Pilot Certificate flying test.  
    The end of the ab initio training period could be regarded as reaching a competence level equivalent to that required for the day VFR private pilot licence; i.e. Pilot Certificate plus the navigation, communications and passenger endorsements. Perhaps you should not aspire to acquire extra endorsements until you have around 50 hours solo experience in your logbook – unless there is a pressing need to do so. Note that the HP (high performance) and LP (low performance) endorsements listed in the image under 'Other endorsements' are no longer relevant.

    4. Competency, ground and flight tests
    All aspects of your performance and progress should be measured objectively, and continuously, against a competency standard required by RA-Aus. There are only three ground examinations and one formal flight test involved in the initial program. The first ground examination is a simple test on the rules of the air (i.e. the traffic rules), which must be passed before your first solo flight. The second is the RA-Aus Basic Aeronautical Knowledge (BAK) test, which must be passed before the Recreational Aviation Australia Pilot Certificate can be issued.

    Also prior to issue of a Pilot Certificate, the student pilot must pass the RA-Aus examination on human factors, airmanship and decision-making.

    The written examinations are generally 'multiple choice', which require you to select one clear answer from three or four possible answers. Your instructor will endeavour to make sure you know your subject beforehand. Also, the flight tests are only undertaken when your instructor believes you have acquired the necessary competencies and recommends to the facility's Chief Flying Instructor [CFI] that you are ready, so you will not be undertaking a flight test unless you are most likely to pass. The flight test is conducted by the CFI to formally assess your airmanship and ability to manipulate the aircraft safely. The Chief Flying Instructor is responsible to the association's Operations Manager — and to you of course — for your ground training, your flight training and your safety at all times.
      After success in the flight test and BAK you are qualified, in one of the three major RA-Aus aircraft groups (i.e. Group A 3-axis, Group B weight-shift trikes or Group D powered parachute) to fly within a radius of 25 nautical miles from the airfield. You are not yet qualified to carry passengers. There are two other Pilot Certificate aircraft group ratings; Group F for foot-launched backpack engine-powered parachutes with an empty weight exceeding 70 kg (HGFA are responsible for the aircraft of 70 kg or less) and Group C for combined control (i.e. combined weight-shift and aerodynamic control inputs) aircraft.
    Incidently, Australia has a long history in flight training. The first pilot or aviator's certificate was issued 17 November 1911, by the Aerial League of Australia, to William Hart for satisfactory completion of the certificate flight test — five continuous figure eights within a 500 metre circuit. It wasn't until 1921, after the 1921 Air Navigation Act came into being (and the establishment of a network of 60 landing grounds for the aerial mail services was commenced), that government-controlled civil pilot's licence and aircraft register systems were introduced "to reduce reckless flying and the number of air fatalities".

    The first Commercial Pilot's Licence was issued in 1921, by the newly established Department of Civil Aviation, to Norman Brearley, ex-WW1 pilot and founder of Australia's first regular airmail and passenger service — West Australian Airways which later became Australian National Airways and, finally, Ansett-ANA.

    5. Certificate endorsements
    When a newly qualified, 3-axis group A pilot receives their Pilot Certificate, it may carry endorsements reflecting the configuration of the aircraft type in which the person trained or is qualified. Those initial endorsements may be: tail wheel; for aircraft with a tail wheel or tail-skid undercarriage rather than the normal nose wheel undercarriage; and perhaps two-stroke engine; if training in an aircraft with a two-stroke engine rather than the normal four-stroke. If you wish to undertake flights that will take you more than 25 nautical miles from the original point of departure you must get a navigation or cross country endorsement. This entails both a flight test and a written examination covering flight planning, meteorology, navigation, and flight rules and procedures. Also you must have accumulated a minimum 10 hours cross country navigation flight training including a minimum two hours solo navex experience.

    You need to gain some familiarity with the control, advisory and information services available from the various air traffic service units of Airservices Australia. Instruction will be provided in the on-line acquisition of weather briefings and current advisory notices to airmen [NOTAM] from Airservices Australia and the Bureau of Meteorology.
       For safety all pilots should obtain a radio operator endorsement, which also allows you more freedom, and ease, of flight — for instance if you want to visit our annual fly-in. It only entails some study of the radio communications procedures in Class G airspace and at non-controlled aerodromes, and a written and oral test by an RA-Aus instructor. In most FTFs you will start learning some radio procedures from your first flight.
    You can qualify for a passenger carrying endorsement to your Pilot Certificate after you have a total of 10 hours solo (i.e. as pilot in command [PIC]), which must include two hours in a RA-Aus two-seat aircraft. The CFI has to be convinced of your personal maturity and you also have to do a flight test to check that you know how to look after your passenger. The pre-flight planning of fuel requirements, passenger and baggage arrangement, assessment of runway and air density conditions, calculation of aircraft weight and balance, and the physical pre-flight airworthiness checking of the aircraft is emphasised, to ensure the flight will be operated safely. All RA-Aus flight training facilities offer the navigation, passenger and radio endorsements.

    At the conclusion of the basic program you, as a certificated RA-Aus pilot, will be fit to carry out the level 1 maintenance; to check the aircraft's airworthiness by reviewing the maintenance release and maintenance log; to do the daily and pre-flight inspections of the aircraft. If you also have the cross country endorsement then you can also fly — in daylight and reasonable weather under the visual flight rules [VFR] — anywhere within Australia. Generally you will be restricted to fly below 10 000 feet above mean sea level, to stay within Class G airspace unless you fulfil some specific requirements of Airservices Australia (the air traffic management organisation), and not fly over towns in some recreational aircraft categories, or designated remote areas, or other prohibited or restricted areas. For fuller airspace information see RA-Aus/HGFA/ASRA powered aircraft flight operations and the other material on that web page.

    6. Fees charged by the FTF
    The flight hours required by an individual vary, particularly according to the flight frequency, i.e. generally someone flying just three or four hours each month will need more hours than someone flying three or four hours every week. Most people, not undertaking a full-time schedule, achieve the Pilot Certificate within 3–5 months.

    For a person who is not the holder of a valid International Civil Aviation Organisation (ICAO) pilot licence (which in Australia would be a CASA licence), RA-Aus regulations require a minimum 20 hours general flying training, including a minimum of 5 hours flying as pilot in command, i.e. solo, before the Pilot Certificate flight test and if this minimum was achieved then the total flying costs would be around A$3000 to A$4000 including the Australian Goods & Services Tax. (The schools charge from $150 to perhaps $220 per flight hour depending on the type of aircraft employed and other factors.) But the typical student time is 15–20 hours flying with an instructor and 8–10 hours solo flying and, like learning to drive, a few students will take a lot longer to achieve a satisfactory competency level in all the required training sequences. The costs you will incur depend chiefly on flight hours and the aircraft type flown. Check the flight training facilities for the FTFs near you, or near where you plan to take a vacation. Accessing the flight school websites may provide comparative information on rates for their types of training aircraft.

    Instead of charging an hourly rate, some FTFs may offer a fixed-price package, or a package negotiated to fit your needs, which you should assess carefully — bearing in mind the range of qualification times mentioned in the preceding paragraph.

    There will also be out-of-pocket expenses for purchase of study manuals and navigation materials. Perhaps you should also consider purchasing your own helmet and communications headset early in your training period.

    In this guide I have included the text of a brochure issued to prospective clients by a flight training facility. You should read this document, which rightly points out that when selecting a flight school, there are aspects other than fees to be considered. Advice is given on setting goals, picking aircraft types to train in, getting started, selecting a school and hints on how training actually happens.

    Not particularly highlighted in the school brochure is the need for the student to be happy with the instructor's personality and training style — not easy to assess on initial contact. The training should reinforce your view that your decision to learn to fly is a wise one and not be a de-motivating experience. Expect value in return for your expenditure — if you are not happy with the customer service provided by the FTF, inform the CFI of your needs; if you are still dissatisfied, take your custom to another school.

    It is also important that the student takes responsibility for their own learning and, with that in mind, I have included a document, titled "Learning to fly: a students viewpoint", written by Dr Carol Richards, a recreational aviation enthusiast and former RA-Aus board member who did much to develop the Airservices Australia–RA-Aus flight training scholarship program for young people.
    7. Costs charged by Recreational Aviation Australia
    Before you can be issued with an RA-Aus Student Pilot Certificate or Pilot Certificate you must be a member of Recreational Aviation Australia and carry the third party legal liability insurance protection. This has been arranged by RA-Aus to cover members for damage to other people's property or person.

    The RA-Aus fee schedule issued July 2014, including GST, is:
    Student pilot joining fee: $210.00; which includes the issue of the Student Pilot Certificate, third party insurance cover, Operations and Technical Manuals, first 12 months RA-Aus membership and 12 months subscription to the monthly Sport Pilot magazine. This journal is the official means of RA-Aus board and executive communication to the members of the association. Issue of Pilot Certificate on qualification: no charge Pilot Certificate endorsements: no charge Annual Pilot membership renewal: $210.00
    (which includes third party insurance cover, amendment service for the Operations and Technical Manuals, and the annual subscription to the monthly journal Sport Pilot.)  
    8. Airfield security ID
    An aviation security identification card [ASIC] must be worn by all persons who need access to the secure parts of some Australian aerodromes. A flight school will advise if students need an ASIC and the RA-Aus staff will handle an ASIC application. The RA-Aus fee for this members-only service is $200, which includes the service charges from the various police, security authorities and the card manufacturer. Download the application form.

    9. After you get your Pilot Certificate
    Most pilots do not buy their own aircraft initially but prefer to join a club where members can hire an aircraft from an associated school, usually paying a flight time hourly charge. One thing about joining a club, you will be well entertained when the members get together to swap tall stories! There are quite a number of sport and recreational clubs in Australia but they normally tend to focus on one aircraft class — 3-axis powered aeroplanes, sailplanes, gyroplanes, hang gliders, trikes, powered parachutes and so on. Your initial RA-Aus Pilot Certificate usually covers only that aircraft group rating in which you qualified.

    If you wish to extend the category of recreational aircraft that you are qualified to fly you will need further instruction in the chosen group before that aircraft group rating can be added to your Pilot Certificate. You can also add endorsements for formation flying, waterborne/amphibian operations and others — so there is ample potential to spread your wings. I will cover this in the advanced flight training section of this guide.

    To continue holding an RA-Aus Pilot Certificate you must remain a financial member of RA-Aus, remain medically fit and undertake a biennial ultralight flight review [BFR] with a Senior Instructor or Pilot Examiner. This two-yearly review helps pilots identify any deficiencies in competency which may have developed. See the Operations Manual section 2.07, subsections 4–5.

    Whether you extend your qualifications or not, you will experience a whole new world of fun with many varied activities within the recreational aviation community. Some of the internet discussion forums may provide rewarding participation.

    10. Pilot licence or pilot certificate?
    To compare the RA-Aus training program with the general aviation program for their Private Pilot Licence we recommend you visit CASA's Learning to fly page. While there, look at the 'Licence Requirements and Entitlements' section.

    Some Australian-designed aircraft, such as the Jabiru, may be registered as a sport and recreational aviation aircraft or as a general aviation aircraft. In fact, many Jabirus are used in flying training organisations from both camps so it is easy to compare the cost of attaining a Private Pilot Licence with that of attaining an RA-Aus Pilot Certificate.

    It is interesting to note that in September 2004, the United States Federal Aviation Administration [FAA] introduced their Sport Pilot Certificate which seems to be having a beneficial impact on US recreational aviation and the associated aircraft manufacturing/distribution industry, with more than 5000 SPCs current in early 2014. The FAA Sport Pilot Certificate is very similar to the RA-Aus Pilot Certificate — the same driver's licence medical standard, the same minimum dual (15) and solo (5) training hours before qualification, and the same concept of only one passenger and maximum aircraft weights — 600 kg for a landplane, 650 kg for a seaplane.

    Since about 1998 CASA has been proposing the introduction of a Recreational Pilot Licence (RPL) within the General Aviation environment. This came into being on 1 September 2014. The RPL is, in many respects, similar to the RA-Aus Pilot Certificate and might provide an alternate path for those who might wish to join sport and recreational aviation without going along the RAAO path. This is not the 'parallel path principle' laid out in the proposed CASR Part 103, implementation of which has also been expected for a number of years. The proposed RPL is based on the USA's existing (but most unsuccessful) Recreational Pilot Certificate, where only about 200 US pilots (just 0.03% of all US pilots) were still certificated 22 years after the introduction of the classification. The FAA's Sport Pilot Certificate has been much more successful.

    Note: the International Civil Aviation Organisation (ICAO) documentation uses the term 'pilot licence' and the British Commonwealth nations of Canada, Britain and Australia employ the 'licence' term for the various pilot qualification documents issued by national airworthiness authorities — such as the Australian Civil Aviation Safety Authority. A 'licence' is a permit from a government authority to do something, which could be to go fishing or to go flying. The United States Federal Aviation Administration uses the term 'airmen certification', e.g Sport Pilot Certificate, Recreational Pilot Certificate, Private Pilot Certificate etc. A 'certificate' is a document issued by an authority that formally attests to the fulfilment of the requirements — or the achievement of the proficiencies — necessary for certification. The Australian recreational aviation administration organisations issue Pilot Certificates on qualification.

    11. Procedure for holders of a valid pilot licence
    Holders of a valid aeroplane pilot licence (e.g. PPL, CPL, ATPL) who wish to obtain an RA-Aus Pilot Certificate can undertake conversion training at an RA-Aus flight training facility to gain familiarity with the flight characteristics of very light aircraft. Prior to undertaking the flight test for the issue of a Pilot Certificate and endorsements, an applicant must complete such dual training as deemed necessary by a CFI and, in any case, shall have not less than 5 hours experience, in an aeroplane registrable with RA-Aus, which shall include a minimum of one hour solo. Of course, licence holders converting to powered parachutes or weight-shift aircraft may need considerably more than five hours of training.

    Holders of a pilot licence which is no longer valid because the period of effectiveness of the last biennial flight review or class 2 medical certificate has lapsed, are also eligible to apply for the Pilot Certificate, however it is likely that lack of recency will affect the conversion flight time necessary. An aviation medical certificate is not required but an RA-Aus pilot must be medically fit to a standard equivalent to that required to hold a private motor vehicle driver's licence in Australia. For more information on the physical condition required for a private vehicle driver licence see 'Assessing fitness to drive'. It is the responsibility of all Pilot Certificate holders to report to RA-Aus any change in their health status which would cause them to be below that minimum health standard required.

    Persons who have not completed their PPL training may utilise their GA training hours towards the RA-Aus Pilot Certificate. However, this depends on acquiring in excess of the minimum 20 hours experience including a minimum of 5 hours solo and the candidate must also demonstrate to the CFI that they successfully meet the standard for the issue of an RA-Aus Pilot Certificate. It may also be necessary to do the RA-Aus Basic Aeronautical Knowledge written test.

    Read paragraph 2 of the Flight Crew Certificate document in the Operations Manual. Email the RA-Aus Operations Manager or telephone 02 6280 4700 to discuss your needs.

    12. Airservices Australia — RA-Aus flight training scholarship program
    The aims of the Airservices Australia/RA-Aus joint scholarship program are to:
    introduce young people to the sport of recreational aviation develop responsible and safe flying attitudes offer a basis of aviation knowledge for advancement and careers in recreational, military or general commercial aviation assist young people to complete their flying training at minimal cost encourage young people to become active long-term members of the recreational aviation community. For more information visit the RA-Aus GYFTS page.

    The next module in this 'Joining sport and recreational aviation' series is an outline of the 'air experience flight'.

    1. Can I learn to fly a sport and recreational aviation aircraft?
    Of course you can. Generally, as long as you are in reasonable physical and mental condition — equivalent to that needed to hold (and maintain) an Australian private vehicle driver licence — you can become a member of a sport and recreational aviation association and learn to fly an Australian sport and recreational aeroplane, just for the fun of it, and at your own pace and convenience. Your medical fitness usually does not need to be confirmed by a medical certificate, but you must sign a declaration that your medical fitness is at least equivalent to that needed for the driver licence. For more information on the physical condition required for the private vehicle driver licence see 'Assessing fitness to drive'.

    However 'reasonable fitness' is all that is required to fly a hang-glider or paraglider and the backpack-motorised versions of those gliders that have an empty weight less than 70 kg.

    You may start flying training at any practicable age but for powered aeroplanes there is an age restriction requiring a person to be at least 15 years old before they can make their first most memorable flight — as 'pilot-in-command', i.e. 'to go solo'. Consequently the minimum age for commencing powered aircraft flight school is at least 14 years. There is no upper age limit — for those who maintain their private vehicle driver licence fitness level.

    2. What sort of aircraft are included?
    Aircraft categories
    An 'aircraft' is defined as 'any machine or craft that can derive support in the atmosphere from the reactions of the air, other than the reactions of the air against the earth's surface [i.e. hovercraft]' and includes 'lighter-than-air' craft [e.g. non-powered hot-air balloons and powered airships] and 'heavier-than-air' craft. The latter includes the power-driven aeroplanes, helicopters and other rotary wing craft, the non-powered gliders and sailplanes plus power-assisted gliders and sailplanes.

    Australian sport and recreational aviation offers a considerable range of aircraft categories, in any of which you can commence, or expand, your flight experience. There is a wide range in the acquisition cost of an aircraft, ranging from around A$4000 for a secondhand hang-glider in airworthy condition to perhaps A$150 000 for a top-of-the-range, carbon-fibre structure, two-place aeroplane fitted with up-market electronic flight instrumentation, navigation and communications systems.

    The following aircraft class descriptions, particularly the weights, are in accordance with Australian regulations; other nations will differ: the lighter-than-air aircraft — non-power-driven hot-air balloons and power-driven hot-air airships the unpowered gliders — hang gliders, paragliders and sailplanes (in the regulatory context, a sailplane is a glider whose empty weight exceeds 70 kg) the power-driven heavier-than-air aircraft spectrum: the very light-weight end (empty weight 70 kg or less) — the small framed wing, one-person, foot-launched, motorised harness (i.e. the engine is not attached to the frame) — plus the light-weight, wheeled cart — powered hang gliders (PHG) and the backpack-motorised, foot-launched powered paragliders (PPG). The PPG and PHG motors are typically 100-200cc, 12-30hp 2-strokes weighing around 16-27 kg and consuming 2-4 litres of fuel per hour. in the middle — the one- and two-place, wheeled carriage, powered parachutes (PPC) low-momentum, single-place, three-axis control, ultralight aeroplanes or weight-shift control trikes; that may be factory-built, or privately-built from commercially-supplied kits or plans, or privately-built from your own design; and must weigh less than 300 kg fully loaded the fixed-pitch rotor, home-built or factory-built, light gyroplanes at the top-weight end — one- and two-place, power-assisted sailplanes and 'motor gliders'. the heavier (up to 600 kg fully loaded), weight-shift control trikes the two-place, rotary-wing gyroplanes (which may be factory-built or home-built from factory-supplied kits) that conform to a 'Light Sport Aircraft' airworthiness certification standard and weigh less than 600 kg fully loaded the generally two-place, fixed-wing, three-axis control aeroplanes* (which may be factory-built or home-built from factory-supplied kits) in various classes that could weigh up to 650 kg fully loaded *Most sport and recreational aeroplanes are designed as 'landplanes', being equipped with a shock-absorbing, wheeled undercarriage for take-off and landing on solid surfaces. However many of those landplanes can be readily converted to 'seaplanes' by replacing the wheeled undercarriage with a pair of fixed, non-shock-absorbing, strutted floats; thus providing the buoyancy required for waterborne operations — at the cost of perhaps a 20% decrease in performance due to the weight and drag of the float undercarriage. This seaplane configuration is usually described as a 'floatplane'. Aeroplanes specifically designed for waterborne operations generally do not have floats, rather the fuselage underbody is shaped as an enclosed, high-speed, hydrodynamically-efficient boat hull; thereby achieving buoyancy with a minimum increase in weight and drag. They utilise small wing-tip floats for waterborne stability. Such seaplanes are flying-boats and, like the floatplanes, are single-engined. A very few seaplanes are mono-hulled floatplanes, see the Lazair electric floatplane. Many seaplanes are also equipped with wheeled landing gear, repositionable into cavities in the hull or the floats during both flight and waterborne operations, while providing an 'amphibian' capability for launching into water, climbing ashore or for solely land operation.

    There is another unpowered aircraft category — gyrogliders — that are not regarded as 'free-flying' aircraft because they are towed behind a land vehicle. They obtain their lift by the reaction of a rotor and are often referred to as 'rotor kites'. Parasails are similar and are also towed but usually by a boat. Both parasails and gyroglider operations are limited by CAO 95.14 to heights not exceeding 300 feet above surface level and there is no requirement for membership of any administration organisation or for formal training. The aircraft flight control and power control systems
    To achieve low cost, light weight and high performance the aircraft design, structural engineering and manufacturing processes involved in producing the airframe, power systems, flight instruments, navigation and communication electronics may be quite complex, but the aircraft operating systems are not.

    The basic flight control systems of the aircraft range through: none for the hot-air balloons; rudder steering control only for the hot-air airships the hang gliders have 'weight-shift control' (i.e. body shift) by the pilot moving their body fore-and-aft or sideways relative to a simple, fixed, triangular control bar and frame system rigidly attached to the wing. The pilot's harness is attached to a hang-point on the tubular metal wing keel structure the microlights/trikes have a similar but more complex 'weight-shift control' system that entails the movement of the whole carriage (that is attached to a suspension joint on the keel of the wing) relative to a control bar. the paragliders (PG and PPG) and powered parachutes have a very simple ram-air parawing system — hand-operated steering/braking toggles or foot-operated steering pedals plus limited weight-shift assistance the sailplanes, aeroplanes and gyroplanes have foot-operated rudder pedals and a hand-operated control column or 'stick', that together provide the three-axis (yaw, roll and pitch) aerodynamic moving control systems. The chemical energy control systems employed are: the propane-burner buoyancy (thus height within the wind gradient) valve system/s of the hot-air balloons and hot-air airships; and the petrol-engine controls of the airship for speed control. the petrol-engine controls of the powered, propeller-driven aircraft, providing their ability to maintain height or to climb, without dependence on atmospheric uplift plus their ability to select an airspeed within a performance range. Once a sport and recreational petrol engine has been started the basic engine operating control is a hand-operated or foot-operated throttle – the same as a road vehicle. Currently there is considerable testing of battery-powered electric motors for aircraft propulsion.

    Persons with physical disabilities should note that — unlike a road vehicle — the placement of the hand/foot operated aerodynamic controls usually cannot be changed in the training aircraft, though it may be possible in your own aircraft. Weight-shift controlled aircraft have only the hand-operated flight control bar; steering when on the ground is normally foot-controlled, but this can be altered to hand-control in your own aircraft. See David Sykes solo England-Australia trike flight.

    3. Who runs sport and recreational aviation?
    The role of the Civil Aviation Safety Authority
    'The primary function of the Civil Aviation Safety Authority (CASA) is to conduct the safety regulation of civil air operations in Australia and the operation of Australian aircraft overseas by means that include, amongst other things, developing, promulgating and implementing appropriate aviation safety standards and effective enforcement strategies to secure compliance with those standards, conducting comprehensive aviation industry surveillance and regular reviews of the system of civil aviation safety, and carrying out timely assessments of international safety developments. CASA also has a range of other safety-related functions, including, amongst other things, providing safety education and training programmes and aviation safety advice designed to encourage a greater acceptance by the aviation industry of its obligation to maintain high safety standards; fostering an awareness in industry management and the community generally of the importance of aviation safety and compliance with the civil aviation legislation; and promoting consultation and communication with all interested parties on aviation safety issues.'

    There are five Australian recreational aviation administration organisations (RAAOs) – each with specialist knowledge and insight into a particular sector of the sport and recreational aviation industry – that provide the flight training for their sector. The RAAOs operate under a deed of agreement [i.e. a contract] with the CASA for the self-administration of that sector. The organisations 'exist to oversight member activities and assure CASA that activities are being conducted safely and in accordance with CASA approved procedure manuals. CASA needs to be fully confident that RAAOs have the risk treatment and governance capacity to provide the safety outcomes required. The Sport Aviation Self Administration Handbook 2010 provides further detail on CASA's expectations for RAAOs and their board members in ensuring that self administration is providing a safe environment for sport aviators*, as well as other airspace users and people and property on the ground.'
    (*Note: sport and recreational aviators and the single passenger allowed, are regarded (in a regulatory sense) as informed participants in the activity being pursued. An informed participant is aware of the risks involved in a particular form of sport and recreational aviation and is willing to accept those risks. How do you make a passenger aware of the potential risks inherent in sport and recreational aviation so he/she can make an informed decision about their participation? Various warning placards must be displayed in the aircraft cockpit but that's hardly sufficient. What if the passenger is legally a child, how can children be considered 'risk-informed'?)

    The arrangement with CASA is that the RAAOs are responsible for the day to day enforcement of standards and operational rules in accordance with the individual RAAO's CASA-approved rules and procedures manuals. Such rules and procedures are designed to meet CASA's required safety outcomes for the 27 000 association members. CASA oversights the RAAOs via their sport aviation office, the Self-administering Sport Aviation Organisations Section, which is part of the Office of the Director of Aviation Safety. That oversight includes creation, and monitoring of, systems for the enhancement of RAAO governance and of safety effectiveness.

    RAAOs set the training and skill standards required of flight instructors and of student pilot members; the latter to qualify for issue of a Pilot Certificate and subsequent endorsements to the certificate. RAAO Pilot Certificate holders are not required to hold any type of CASA Pilot Licence. You cannot learn to fly — or continue to fly once qualified — unless you are a financial member of the relevant organisation. Unfortunately this means that if your interests extend over several sectors, you will have to be a paid-up member of several RAAOs.

    Generally RAAO members won't come into contact with CASA officers, however, officers from the Self-administering Sport Aviation Organisations Section do carry out 'ramp check' inspections on pilot and aircraft after landing or before take-off at any airfield where sport and recreational aircraft are operating; see 'Staying within the rules'. The flight training recreational aviation administration organisations
    RAAOs are 'not-for-profit' associations of like-minded individuals that administer their sector for the benefit of Australian recreational and sport aviation in general and their membership in particular.

    The regulatory authorisations involved may be: acceptance of a factory-built or home-built/kit-built aircraft type into their jurisdiction issue of the certificate of registration required for aircraft over 70 kg empty weight issue of aircraft airworthiness certificates (where applicable) issue of pilot certifications and other qualifications issue of aircraft maintenance qualifications ongoing approval of associated flying training and maintenance training facilities oversighting membership activities enforcement action where members are in breach of the rules.  
    The five ab initio ('from the beginning') flight training RAAOs are:
    The Gliding Federation of Australia (GFA) was formed in 1949 and became Australia's first national aviation self-administration organisation in 1953. GFA administers the higher performance, higher cost sailplane sector — recreational and regional/national/international competitive soaring*. GFA is an organisation of about 86 clubs contained within five regions with a total membership around 12 000. The clubs have a considerable authoritative role within GFA, on top of their supportive and social roles. About 1200 sailplanes, power-assisted sailplanes and motor-gliders are associated with the GFA. The sailplanes are the only 3-axis control aerobatic aircraft in the RAAO administered sector of sport and recreational aviation.

    *Soaring is the art of using only atmospheric uplift (orographic ascent, convection or solitary wave and lee wave motion) — that is greater than the aircraft's sink rate in normal circling flight — to gain height. The aircraft may then glide some distance losing height until another source of lift is used to regain it and so on until a considerable distance has been travelled — thermal soaring for example. If a source of orographic lift is available from a raised topographic feature such as a coastal cliff, escarpment, hill, ridge or mountain, then height can be maintained for a considerable time, but within one location — ridge and hill soaring.

    The paragliders, hang gliders and sailplanes have soaring ability and the competitive nature of gliding produces finely honed pilots who have a high appreciation of atmospheric motion, as sources of lift (i.e. ascending air) but also as sources of risk.
      The Hang Gliding Federation of Australia (HGFA). Formed in 1978, administers the lower performance, lower cost glider sector — hang gliding and paragliding (including motorised hang gliding and motorised paragliding). HGFA is also one of the two RAAOs (RA-Aus is the other) that administer powered weight-shift control trikes or microlights — occasionally used for tug-launching of hang gliders. There is a strong national and international competitive FAI hang gliding scene. HGFA has about 2500 members, 44 commercial flight schools and 50 clubs located throughout Australia.
      The Australian Ballooning Federation (ABF). Formed in 1978, administers recreational, adventure and competitive FAI lighter-than-air private balloon flying. ABF is also responsible for hot-air airships. There are about 350 hot-air balloons on the Civil Aviation Safety Authority's aircraft register, equally split between private and commercial ownership. There are 5 regional associations/clubs.
      Recreational Aviation Australia (RA-Aus), formed in 1983 (see the history), administers the powered light recreational aeroplane scene in Australia, including seaplanes, weight-shift control trikes and powered parachutes (PPC). The weight-shift control trikes are also administered by the HGFA. There is no FAI competitive flying or Colibri badge program. RA-Aus has grown to a membership of around 10 000 persons who own and operate about 3400 aircraft with a current market value around $135 million. There are commercial flight schools in about 180 Australian locations with some 450 instructors. There are about 100 recreational clubs, performing a supportive and social role, which — unlike the GFA and HGFA organisations — act quite independently of RA-Aus, although many are affiliated with RA-Aus. See the RA-Aus mission statement.

    Note: in September 2014 CASA introduced their Recreational Pilot Licence (RPL) which is based on the United States Federal Aviation Administration's* Recreational Pilot Certificate and very similar in concept to the RA-Aus Pilot Certificate. The RPL authorises a person over 16 years of age to pilot a single-engine aircraft that has a maximum certificated take-off weight of not more than 1500 kg, by day under the visual flight rules – if the aircraft is engaged in a private operation. The aircraft must be listed on the Australian civil aircraft register, not an RAAO aircraft register. The same Australian private vehicle driver licence medical conditions apply. Persons on board is generally limited to one passenger plus the pilot. For more information see the CASA RPL information brochure. A Recreational Pilot Licence holder may not act as pilot-in-command of an RA-Aus registered aircraft unless that pilot is also a RA-Aus member and a RA-Aus Pilot Certificate holder.

    *The Recreational Pilot Certificate was introduced by the FAA in 1989, following pressure from the American Aircraft Owners and Pilots Association, but was never successful; after 22 years there were only about 200 recreational pilot certificates in existence, about 0.03% of the 625 000 FAA certificated pilots in the USA. The experience in the USA perhaps indicates that the RPL may not be a resounding success though, in Australia, it is a stepping-stone on the way to qualifying for the Private Pilot Licence (PPL). Also it does provide the means by which an RA-Aus pilot certificate holder can readily obtain a CASA pilot licence.
      The Australian Sport Rotorcraft Association (ASRA) administers gyroplanes and gyrogliders. Although the term 'rotorcraft' encompasses both gyroplanes and helicopters, the organisation administers gyroplane operations only. There are about nine regional clubs associated with the organisation with about 40 flight instructors in the clubs.  
    Sport aviation RAAOs and associations within General Aviation
    The term General Aviation (GA) describes the sector of Australian aviation that includes both private flying and commercial aviation (but not scheduled airline transport) and thus a significant number of professional pilots. GA is mostly administered directly by the CASA. GA aircraft operate both within controlled airspace and outside controlled airspace and under the 'visual flight rules' or the 'instrument flight rules'. There are several GA groups with some association with sport aviation.
    The Australian Parachute Federation (APF) RAAO was formed in 1960 to administer and represent Australian Sport Parachuting. Skydiving clubs were first formed in Australia in 1958. There is much to learn in the sport — skydiving (i.e. stable, controlled freefall), formation skydiving, wingsuiting, canopy formation and other variations. APF states that some 70 000 people undertake 'tandem' jumps each year.
      The Australian Warbirds Association Limited self-management organisation was incorporated ' to bring together aircraft owners, operators, restorers, maintainers, historians and enthusiasts to share their passion for ex-military aviation and to promote and preserve Australia's proud military aviation heritage.' AWAL is the very successful self-administration body for around 400 warbirds in the 'Limited' certification category, ranging from Tiger Moths to jets. Some owners offer 'Adventure Flying' to paying passengers.
      The Sport Aircraft Association of Australia (SAAA) RAAO is an association of around 1400 'aviation enthusiasts assisting each other to build, maintain and operate sport aircraft. We educate members to continuously improve safety outcomes.' The members aircraft are registered by CASA in the Experimental category. The association has similar aims to, but not the same breadth of, those of the US Experimental Aircraft Association (EAA).
      The Australian Aerobatic Club (AAC) was 'formed to foster interest in the sport by providing opportunities to train and compete. The AAC is responsible for the administration of the sport of aerobatics in Australia' and is affiliated to FAI via its ASAC membership.
      The Seaplane Pilots Association of Australia is an independent organisation with about 450 members around Australia; membership is free. General Aviation pilots predominate but RA-Aus pilots participate.  
    Other sport and recreational aviation RAAOs and associations
    The Model Aeronautical Association of Australia (MAAA) RAAO is the Australian governing body for aeromodelling and is affiliated to FAI via ASAC. In a regulatory sense model aircraft are regarded as small unmanned aerial vehicles (UAVs) used for sport and recreational purposes only.
      The ABF, GFA, HGFA and APF are members of the Air Sport Australia Confederation (ASAC), which was formed in 1989 as a national confederation of sport and recreational aviation organisations to act as a lobbying body in respect to Commonwealth and State goverments and Commonwealth aviation authorities. ASAC is also Australia's representative on the Fédération Aéronautique Internationale. ASRA and RA-Aus are not ASAC members.  
    FAI: the world air sports federation
    Founded in 1905, FAI is the Fédération Aéronautique Internationale; the international governing body for air sports and aeronautical world records. Participation in FAI-recognised competitions requires entry of pilot particulars into the FAI data base and issue of an FAI sporting licence number — if a pilot wants to be included on the FAI World Pilot Ranking.

    The FAI Sporting Code consists of the General Section and a number of specialised sections, one for each air sport. The Code deals with three major areas: firstly, organised sporting events such as championships and competitions, secondly, records, and thirdly the validation of specified performances for Certificates of Proficiency or Colibri badges. See FAI Sporting Code section 10 ' Microlights and Paramotors'.
    Balloons and airships Aeroplanes Gliding Aeromodelling Parachuting Aerobatics Hang gliding and paragliding Astronautic records Rotorcraft Microlights* and paramotors Human powered aircraft Unmanned aerial vehicles Solar-powered aeroplanes *In FAI classifications a 'microlight' is defined as a fixed- or flexible-wing, powered aircraft with gross weight not exceeding 300 kg if single-place and 450 kg if two-place plus stall speed not exceeding 65 km/h (35 knots). National interpretations of the term vary considerably, though the European Joint Aviation Authorities' definition is the same as the FAI.

    4. Where can I fly?
    Normally, aircraft administered by one of the five flight training RAAOs may freely operate over land under the day visual flight rules [VFR] and outside controlled airspace [OCTA] at heights below 10 000 feet above sea level. The total volume of airspace available for sport and recreational aviation (included between the average land mass elevation of 1100 feet and 10 000 feet above sea level) is some 20 million cubic kilometres. Of course sport and recreational pilots usually would not choose to fly over densely forested, mountainous terrain (except at the periphery) or through any dangerously remote inland areas. Flight over cities and towns is generally forbidden.

    However, the problem is to locate suitable aircraft operating areas at a reasonable distance from home. Unpowered hang gliders and paragliders tend to operate in groups with ground crews and generally need elevated sites for foot-launching, coupled with suitable areas for landing that also provide reasonable road access for the recovery crew. Powered hang gliders, powered paragliders and powered parachutes don't need an elevated site for launching, only a suitable, but not large, open field for launching and recovery and it is feasible for flights to be operated independently. Sailplanes must operate from fairly large, open airfields suitable for aero-tow, vehicle-tow or winch launching and there must be a well-drilled group from the club ensuring that all aspects of every launch and recovery go smoothly and are completely safe. GFA regulations do allow for 'independent operators' (motor-gliders for example) but they are still tied to a club.

    Sport parachutists must operate in groups and in drop zones authorised by the Civil Aviation Safety Authority.

    Aeroplane, gyroplane and trike pilots tend to operate quite independently (perhaps 20% are club members), occasionally arranging joint flights, 'get-togethers' or 'fly-ins'. All such aircraft can operate from normal airfields, most can operate from reasonably large and smooth paddocks, some — the short-landing and take-off (STOL) aeroplanes — can operate from small, rough, sloping sites, see the Snowy Plain airstrip.
    5. The 'exemption' legislation enabling recreational aviation
    Aviation in Australia is a highly regulated activity but in sport and recreational aviation much of the day-to-day enforcement of standards and operational rules is undertaken by the RAAOs. So eight Civil Aviation Orders (CAOs) exist to provide recreational aviation with the necessary operating exemptions from some sections (listed within each CAO) of the Civil Aviation Regulations but, of course, all other current legislation could apply to RAAO registered aircraft and RAAO certificated pilots. Excluding CAO 95.14, the content of the seven remaining CAOs has been made as uniform as possible.

    These exemption CAOs are:
    CAO 95.4 for GFA sailplanes CAO 95.8 for HGFA hang-gliders and paragliders (including powered variants) CAO 95.12 plus CAO 95.12.1 for privately operated ASRA gyroplanes with empty weight not more than 250 kg (95.12) and maximum gross weight not more than 600 kg (95.12.1) CAO 95.14 for parasails and gyrogliders (membership of an RAAO is not required ) CAO 95.54 for ABF hot-air balloons and hot-air airships CAO 95.10 for RA-Aus and HGFA low-momentum ultralight aircraft between minimum 70 kg empty weight and 300 kg maximum loaded weight at take-off CAO 95.32 for RA-Aus and HGFA weight-shift controlled aeroplanes [aka trikes or microlights] and for RA-Aus powered parachutes, with variable gross weights up to 650 kg CAO 95.55 for the larger 3-axis controlled RA-Aus aeroplanes, with variable gross weights up to 650 kg. If you are interested in the structure of Australian aviation legislation read the document 'An overview of the legislative framework enabling recreational aviation'.

    6. Becoming a member of the RA-Aus powered light recreational aviation community
    The self-administered RA-Aus aviation community is distributed Australia-wide; chiefly operating throughout rural and regional districts and, naturally enough, with a concentration in the eastern states. The safety and the rights of 10 000 members are the core concern of the association. Membership is drawn from most socio-economic groups, the average age is around 50, with a preponderance of males throughout all age groups.

    The low participation rate of younger Australians in all forms of powered sports and recreational aviation is a national shortcoming that RA-Aus recognises and aims to improve. See the RA-Aus — Airservices Australia flight training scholarship program.

    If you don't know anyone associated with RA-Aus recreational aviation then it is probably best to make the acquaintance of a club or training facility or you could contact an RA-Aus state representative or a staff member to discuss your introduction into our community. More information is available in the RA-Aus flight training outline section of this guide.

    The members' monthly journal 'Sport Pilot' will give you some insight into sport and recreational aviation. Available on the RA-Aus website or posted to members, it is the official medium for communication to the membership, containing the President's report on policy implementation progress and monthly reports from the CEO, the Operations Manager or the Technical Manager plus the latest Airworthiness Notices and Service Bulletins. It also contains articles of general interest and a 'members aircraft for sale' section.The magazine is available to non-members via annual subscription from the RA-Aus on-line shop.

    Another opportunity to get a broad view of this form of recreational aviation is at NATFLY, the annual four-day Easter (Friday through Monday) get-together at Temora aerodrome in New South Wales. Around 25% of the 3400 RA-Aus registered aircraft attend the event. The national fly-in also provides a venue for Australian manufacturers and importers to introduce new and forthcoming aircraft and aviation products. NATFLY allows the opportunity for home-builders to display their finished projects and, perhaps, win one of the achievement awards. Also view the history of the 'Come and Get It Trophy' for an insight into some 10 000 km flights (within Australia) undertaken by sport and recreational pilots.

    The typical RA-Aus member is a 50-year old male who has always wanted to experience 'seat-of-the pants' flying, is now relatively free of family, work pressures have reduced somewhat, has some mechanical or practical aptitude, enjoys reasonable health and lives in a rural, regional or outer capital city area where there is a non-towered airfield in the district or there is suitable space for an airstrip. There is a tendency for that typical member to have had some past association with the defence forces and quite a few are, or have been, general aviation or airline pilots. But of course there is a wide variance from the 'typical' within the 10 000 RA-Aus members.

    Should you decide to join RA-Aus you can download the necessary Application for Membership – Student Pilot' and return it to the RA-Aus office — or a flight school can provide the form and process the paperwork.

    The RA-Aus sister self-administration association, the Hang Gliding Federation of Australia, also supports powered light recreational aviation in the form of CAO 95.10 and CAO 95.32 trikes and as self-launching gliders — hang gliders with a lightweight, perhaps 15 hp, two-stroke engine plus propeller in the rear of the harness boot (hang-motors), paragliders with a backpack engine and propeller (paramotors), and lightweight trikes (nanolights). The empty weight of machines in the self-launching group must be under 70 kg to avoid classification within CAO 95.10 and CAO 95.32.

    Recreational aircraft amateur builders
    About 40% of RA-Aus members are owners, co-owners or owner-builders of sport and recreational aircraft. Nearly half the aircraft with current RA-Aus registration are homebuilt and, at any time, there are a substantial number under construction. Such aircraft are either designed by the builder; for example, Daryl Patterson's 'SE5A', built from plans — Peter Franks' 'Jenny', or built from commercially supplied kits — Peter Loveday's 'Storch'.
    Home builder, and RA-Aus Life Member, Lynn Jarvis's Sonex aircraft received the award for best overall aircraft at NATFLY 2004.
    The balance of this 'Joining sport and recreational aviation' guide describes learning to fly in the sector of aviation administered by Recreational Aviation Australia Incorporated. That sector includes home-built or factory-built, 3-axis control, single-engine aeroplanes including seaplanes, weight-shift control 'trikes' and powered parachutes. These aircraft may be one- or two-place with a gross weight up to 600–650 kg. The next module in this series is an outline of flight training for pilot certification in RA-Aus 3-axis aeroplanes, trikes or powered parachutes including an estimate of costs.

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