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Rev. 45a — page content was last changed 1 February 2013
|Flight Planning and Navigation|
The four elements of aerial navigation are position, direction, distance and time — and distance/time is ground speed.
The four parameters for assessing the performance of a navigation system are: integrity, accuracy, availability and continuity of service. If a particular navigation system is demonstrated to satisfy all four parameters for a flight phase then it may be classified as a sole-means navigation system — for that phase. When operating under the day visual flight rules [day VFR], en route navigation by map reading and visual reference to the ground satisfies all four parameters for all flight stages of a sole-means navigation system.
There are four navigation techniques used in flight under the visual flight rules — pilotage, dead reckoning, position-fixing and homing. Pilotage and dead reckoning are the primary navigational techniques for pilots of light recreational aircraft and, like many air navigation terms, they are centuries-old nautical terms.
The first steps in flight planning entail selecting a safe route, plotting it on a chart, checking the status of airfields along the route, ascertaining general weather conditions and calculating preliminary fuel requirements.
Elrey B. Jeppesen in the 1920s, for the early air mail pilots in the USA, were just notes about the landmarks along a route. As accurate aerial charts became available then aerial dead reckoning became much more refined.
Map reading is the essence of pilotage. It entails: a continuous in-flight survey of the planned route (pre-plotted on the chart); identification of the upcoming chart features on the ground (i.e. reading from map to ground); and determining the actual location relative to the planned position. Following the determination of that position (and thus the actual path over the ground) dead reckoning is then used to determine the 'navigation solution':
Only when uncertain of your position will it be necessary to note prominent ground features and their relative positions, and then find those features on the map; i.e. reading from ground to map. Map interpretation is an acquired skill. An inability to relate the map to the ground features in view is a common experience on the initial attempts. Some find it very difficult to master. In the more remote, and rather featureless, areas of Australia what seem to be major features on the surface may not be shown on the chart, and vice versa. Dead reckoning [DR] is deriving the current position, or a future position, mathematically from a planned position or the last known position. DR for light aircraft is, or should be, essentially simple navigation by clock, compass and mental arithmetic. Most of the DR for RPT and military aircraft is done within the electronic circuitry of advanced navigation systems such as inertial navigation systems [INS], which calculate a new position, from the previous position, about 100 times per second.
DR has a limitation in that errors in plotting or wind velocity estimation or course steering and timing are cumulative, and the true position of the aircraft can't be verified unless it can be determined by pilotage (landmark reference) or some other position fixing technique. En route navigation using the GNSS' module. The non radio-based position-fixing techniques are celestial — star sights or sun sights. Charles Lindberg's pioneering 33.5 hour 1927 New York-Paris flight was mostly dead reckoning with some star sightings, when he could see them. Supplementary navigation techniques' section.
Note: in addition there is a module describing 'Electronic flight planning and the electronic flight bag'.
digitised NATMAP 250K map on a Windows desktop or laptop in the initial planning stage when you need more surface detail than that provided by a WAC. Google Earth may also be handy in locating or verifying the position of small private strips/ landing grounds.
Route construction is often done the day before planned departure, or even earlier if an extensive cross-country flight is planned.
With a soft pencil and a rule, draw a preliminary line on the chart between your departure and destination — you may have to overlap charts, but be aware that WAC and VNC are at different scales. Check along the line for areas to be avoided; i.e. 'tiger country' — rough, forested or hilly areas where there is a limited availability of open, cleared, flat land for an emergency landing. If possible, avoid long stretches of featureless terrain and also designated remote areas. If you are using a WAC, check the relevant ERC-L for CTR, PRD and CTAF aerodromes and mark them on the WAC. Note any other airfields near the line. Now decide which areas of terrain to avoid and find a suitable diversion around them. If that diversion takes you quite a distance from the direct line then so be it; it won't make that much difference to the total distance flown. If there are areas of scenic or other interest evident on the chart, you might plan to overfly them — even if it does makes a zigzag path. Airservices Australia Flying Guides and Publications contains a lot of information to assist in planning flights around Sydney, Melbourne, Brisbane, Canberra, Adelaide and Perth to avoid violations of controlled airspace; look for the link to 'Visual guides'.
Note that on VTCs any area where the elevation does not provide at least 500 feet clearance between the terrain and the lower limit of the overlying CTA is tinted purple; such areas must be avoided. You may also find that when threading your way around CTRs, the clearance between the terrain and the overlying CTA may be so limited that all aircraft in Class G would be flying at much the same low height and tracking over the same ground, — this provides the conditions for a mid-air collision. Also in such terrain there is a significant possibility of strong lee downflows. Never plan to fly such routes unless a reasonable visibility is forecast and the winds around 3000 feet amsl are below 20 knots.
The Australian Transport Safety Bureau Web site contains a research report in PDF format Limitations of the See-and-Avoid Principle, which is recommended reading.
When planning to track near a CTR be aware that you must apply a tracking tolerance — offsetting it at least one nautical mile from the boundary of controlled airspace — if flight is planned below 2000 feet agl, or two nautical miles if between 2000 and 5000 feet agl; watch out for the overlaid CTA steps. A VHF radio is advisable when planning to operate close to a CTR because it is good airmanship to let them know you are there — if a heavy RPT aircraft is being let down overhead there is always a chance of being caught in sinking wake turbulence. Also if you do get caught between rising terrain and a lowering cloud base you can always call Air Traffic Control and inform them that you "require entry" to pass through the edge of the CTR because of deteriorating weather. ATC are always very helpful but unauthorised entry into the CTA or CTR (the dreaded 'violation of controlled airspace' or VCA) is a safety hazard and may earn a substantial fine. Read the article 'Lost in controlled airspace' in the online version of CASA's magazine Flight Safety Australia: November - December 2001 issue. Also see Airservices Australia's document 'Safety net: safe operations around controlled airspace'.
You need to find readily recognisable point locations or waypoints for monitoring flight progress and/or to mark the points of diversion and consequent turning points. Suitable waypoints are airfields with formed runways, major road junctions, small towns, grain silos near rail lines, intersecting line features and distinctive permanent water features — though in drought conditions such features may not be obvious. You may also see some highly visible linear features — roads, railways, rivers, beaches — that roughly parallel your intended track for a reasonable distance. Plan a track divergence to intercept and then follow such line features — and be aware of the 'Rules of the Road' that require aircraft to track to the right of a line feature, or when flying within a valley or any air traffic lane. In the more remote areas of Australia the distances between verifiable landmarks are great and in such cases the only viable route is to follow sealed roads. Mark all the turning points on the chart, joining them to form the route segments of the required track. These turning points will also be used as fuel consumption checkpoints. Generally speaking, a route that provides the best visual fixes and reasonably short segments is the best option.
Measure the total track distance using the scale (in nautical miles) printed on the map or alternatively use the latitude graticule printed along the meridians; each mark is one minute of latitude or one nautical mile. The printed scale is easier to read and thus less prone to errors. (You can buy a ruler scaled in nautical miles for use with WACs, VNCs and VTCs online from the Airservices Australia online store navigation and planning accessories — and buy a protractor at the same time. ) Divide the total track distance by the cruise speed to get an approximate total time required. If the total time required is greater than the known maximum sector time, then the flight must be broken into two or more sectors by introducing refuelling stops at appropriate distances. This probably necessitates replanning the waypoints so that one or more coincide with an airfield with assured and suitable fuel supplies. Re-plot the route if necessary.
If the total time required is less than the maximum sector time, then the first-cut plan for the route to be followed may be viable — but we have not yet taken into account the effects of wind, which may be considerable; these are covered in the next module. Forecast weather and winds should be ascertained as close to the planned departure time as possible, but it is advisable to obtain a preliminary weather forecast the evening before the flight. If a very long flight is planned it is advisable to watch the weather patterns for a few days prior to the trip. Any NOTAM applicable to the area in which you intend to operate should also be obtained at that time. See section 3.6.
In some circles that's termed IFR — not Instrument Flight Rules but 'I Follow Roads/Railways' meaning you plan to keep prominent line features in sight throughout the flight. It's a good philosophy if you are only interested in pilotage and not the challenge of dead reckoning. This purely pilotage technique doesn't preclude the requirement for proper pre-flight planning — it's just that there will tend to be a lot more heading changes than otherwise, and estimation of ground speed and re-estimation of arrival times are a bit rougher.
The 'I Follow Roads' technique is different from the need to plan dead reckoning flights in remote areas of inland Australia so that they track along or near major roads — which may be the only verifiable landmarks in otherwise featureless or uniform terrain. There is a corollary in that aircraft operating under the Instrument Flight Rules must also track along designated air routes when flying from A to B, and these air routes may not be the straight line track between departure and final destination.
CTAF airfield which is not certified or registered. Some aerodromes have a locally operated facility — a universal communications facility [UNICOM] usually on the CTAF (but it may be on another frequency) — which provides information on local conditions. If such a facility is operating at a CTAF airfield it is possibly unwise to enter the circuit if not VHF-equipped, as other aircraft operating in the area may not be as vigilant as they should. For more information see R/T communications and procedures in the 'VHF radiocommunications guide'.
Public airfields are usually owned by a local government body and landing permission is generally not required, although it is always wise to check. Private airfields usually cannot be used without prior permission from the owner, except in an emergency — even then there may be problems with trespass. Landing and parking charges apply at many airfields.
If the airfield is not shown in ERSA it will be a small private operation — possibly with a listing in the Australian Aircraft Owners and Pilots Association publication 'Airfield Directory', which has details of about 2000 airfields, including whether prior landing permission is required. If an airfield is not listed in ERSA or the AOPA Airfield Directory, then it is most unwise to contemplate using it without contacting the owner. Even if landing permission is not required, you should always pre-check with the owner/operator about hazards and conditions. It is too late to find out the surface has been softened by rain when you are up to the axles and about to flip over or find out about the wire across the landing path by striking it.
Using a Google Earth image — found by the location latitude and longitude coordinates — may be a useful source of visual information for airstrips that don't appear in ERSA.
CAR 92 'Use of aerodromes' states in part: A person must not land an aircraft on, or engage in conduct that causes an aircraft to take off from, a place that does not satisfy ... the following requirements ... is suitable for use as an aerodrome for the purposes of the landing and taking-off of aircraft ... and, having regard to all the circumstances of the proposed landing or take-off (including the prevailing weather conditions), the aircraft can land at, or take-off from, the place in safety. The civil aviation advisory publication CAAP 92-1 (1) 'Guidelines for aeroplane landing areas' expands the CAR 92 'circumstances' to be considered by ' setting out factors that may be used to determine the suitability of a place for the landing and taking-off of aeroplanes. Experience has shown that, in most cases, application of these guidelines will enable a take-off or landing to be completed safely, provided that the pilot in command: (a) has sound piloting skills; and (b) displays sound airmanship'.
CASA have produced two advisory publications to support CTAF procedures and provide guidance on a code of conduct to allow greater flexibility for pilots when flying at, or in the vicinity of, non-towered aerodromes. These Civil Aviation Advisory Publications (available on this website) are: CAAP 166-1 'Operations in the vicinity of non-towered (non-controlled) aerodromes' and CAAP 166-2 'Pilots responsibility in collision avoidance in the vicinity of non-towered (non-controlled) aerodromes by 'see and avoid'.
Note that the 'ultralight' term used in the CAAPs when recommending a 500 feet circuit height, refers only to those minimum aircraft which have a normal cruising speed below 55 knots, or thereabouts.
CASA has produced an online interactive learning tool titled 'Operations at, or in the vicinity of, non-towered (non-controlled) aerodromes' which is now available at CASA online learning.
Also read 'Operations at non-controlled airfields' and 'Safety during take-off and landing'. The current ERSA should be fully consulted; particularly check the circuit procedures, stated hazards and whether the airfield is certified or registered, thus requiring use of VHF radio. micro-meteorological and dust hazards. Check runway directions and expected wind conditions, and be wary of airfields with single runways; crosswind conditions may be beyond your aircraft's capability. Be particularly wary of airfields with 'one-way' strips — they are extremely tricky, if not outright dangerous, for those not familiar with any topographic turbulence, sink or other atmospheric hazards that could exist. Low-lying strips may be badly softened by rain or inundation. The availability and location of suitable fuel should be checked. Remember, just because your assessment concludes that you can safely land at a particular airfield it does not guarantee that you will be able to take-off safely.
Note: ERSA location indicator codes. all Australian licensed, and most unlicensed, airfields are assigned a four-letter identity, where the first letter is 'Y' (e.g. Albury = YMAY). Navigation aids such as an NDB or VOR have a three-letter code (e.g. Eildon Weir VOR = ELW) and visual waypoints marked on charts have a three or four-letter code (e.g. Eldorado = ELDO).
Before undertaking a cross-country flight, the pilot must know the total usable fuel capacity and the rate of consumption at the planned cruising speed. The fuel consumption rates supplied by engine/aircraft manufacturers, unless contained in a formal pilot's operating handbook, must be viewed somewhat sceptically; they may be achievable with an 'as new' engine cruising at the best endurance power setting, but are not reflective of the consumption at a more useful cruise speed, say that at 75% power. Fuel must be allowed for consumption at the departure airfield, for the climb and for circuit delays and landing at the destination or an alternate airfield. In addition, the pilot is required to plan a fixed fuel reserve. The reserve amount planned is a matter of personal discretion and the capacity of the fuel tank. It should not be less than 30 minutes in good flying conditions but a greater amount — perhaps 60 minutes — when there is any doubt about the wind velocities or other conditions.* This reserve should not be planned for use; i.e. whether the aircraft is finally landed at the planned destination or the alternate airfield there ought to be at least 30 minutes fuel in the tanks. The fixed fuel reserve concept still applies even if the planned flight is just a local flight terminating at the departure airfield — or a session of circuits and touch'n go's.
*Note: The CASA civil aviation advisory publication CAAP 234-1 'Guidelines for aircraft fuel requirements' provides information and guidance on the fuel requirements for aircraft required by CAR 234. CAAP 234-1 suggests a 45 minute fixed fuel reserve for piston engine VFR aeroplanes. For recreational aircraft perhaps 45 minutes for engines of 70 hp and above and 30 minutes fixed reserve for the smaller engines (the 2-stroke and 4-stroke half-VW designs of 'low-momentum ultralight aeroplanes' tend to provide less 'time in the tank'), but read CAAP 234-1.
When planning a cross-country flight, the objectives are to arrive at the planned destination safely with a reasonable reserve of fuel in hand and without affecting the safety of others while en route; or even creating a possibility that safety might be affected. But remember the first rule of aviation — fly the aeroplane at all times, navigate when able and always be a few minutes ahead of the aeroplane. When navigating a very light aircraft, and particularly an open-cockpit ultralight, a person's capacity for mental arithmetic is not as good as it is when sitting at home. Nor is it easy — or maybe even possible in a weight-shift control aircraft — to manipulate navigation tools in flight and it is very difficult to handle charts, pencils and notepads in the cockpit. Pre-flight preparation should be directed towards reducing and simplifying the in-flight work load.
You should have a good acquaintance with the flight envelope of the aircraft, both with and without a passenger. In particular you must know the optimum cruise speeds obtained when cruising at, say, 75% power plus the proven fuel consumption, in litres per hour — at that throttle setting and aircraft weight. Calculate the maximum sector time allowable by dividing the total usable fuel capacity by the hourly consumption to find hours; then deduct 30 minutes reserve fuel to arrive at the maximum advisable sector time. For example let's say our aircraft has a fuel capacity of 66 litres with 64 litres usable; proven consumption at 70 knots normal cruise is 16 litres/hour. Then maximum sector time is 64/16 = 4.0 hours or 240 minutes; less 30 minutes fuel reserve = 210 minutes. Never equate fuel consumption with distance, only time.
Light aircraft consume 40% or 50% more fuel in a maximum power climb than at a normal cruise setting. It is normal practice to initially climb away at best rate of climb speed (Vy) until a safe height is reached, then airspeed is allowed to increase to a suitable en route climb speed, while maintaining maximum allowed climb power, until the cruise altitude is reached. The extra fuel consumption during the climb can be estimated from the normal rate of climb achieved. For example, rate of en route climb 250 feet/minute = four minutes per 1000 feet, then extra fuel consumed (~50%) is two minutes fuel per 1000 feet climbed. This extra fuel will be used whatever power setting is used in the climb; it is the chemical energy exchanged for the potential energy of height.
There are several articles in the online version of CASA's magazine Flight Safety Australia that are recommended reading. Look under 'Fuel management' in our categorised index of the articles of particular interest to recreational pilots in Flight Safety Australia.
(A larger 141 kb plot image is available. It will open in a new browser window.)
The chosen route utilises the 100 nm of low (elevation about 300 feet amsl) country, extending eastward from the departure airstrip where atmospheric conditions are likely to be less turbulent, with an east-west railway as a good line reference. There are two sentinel hills (Warraway Mountain) south of the rail line and about 75 nm east of Oxford that will provide a distinctive landmark for a turning point. The elevations shown are 895 and 987 feet, thus rising about 600 feet above the surrounding plain. All elevations on the WAC are in feet. We also note that there are two good alternate airfields in the vicinity, Lake Cargelligo and Condobolin, and find that the latter is 58 nm east of Warraway Mountain while Lake Cargelligo is 20 nm south-east of that hill (off the map image). Checking ERC-L(5) we find there is no special use airspace — restricted or danger areas — in the vicinity of our planned operation.
About 50 nm north-east of Warraway Mountain and at the top of the watershed is a distinctive road junction, suitable for the second waypoint. Note the figure 1584 in bold type, just above the road junction — this indicates the highest elevation (Mt Susannah) in that WAC grid section. Similarly the figure 1528 just to the right of the junction indicates the location of the highest elevation in the neighbouring grid section. Thus we will have good indication of track holding from quite a distance if we appear to be tracking towards a position midway between those high points. Also there is a road about 20 nm north-east of Warraway Mountain, which we will cross at right angles, to provide a good ground speed check.
The last segment is a 30 nm run following the valley downslope direct to Tottenham, which, from ERSA, has an elevation of 780 feet. There is a cautionary note in ERSA that a significant animal hazard (kangaroos?) exists on the airfield. Tottenham should be readily recognised from a distance by the distinctive pattern of minor roads, the rail line coming from the south-east and terminating at Tottenham, plus the mine (indicated by the crossed pick and hammer symbol) and a large grain silo. The symbol for the latter is difficult to see but it is right against the western edge of the purple circle indicating the airfield. The total distance of the three route segments is about 155 nm, very little more than the straight line route and much easier pilotage.
The approximate sector time will be 155 divided by our 70 knot cruise = 2.2 hours or 132 minutes, well within our maximum sector time of 210 minutes. Thus the flight will be viable — if the weather is favourable.
Checking ERC-L(5) the relevant Melbourne FIS communications frequencies are ML 124.9 for the first two legs and ML 123.9 for the final.
• Centre the protractor on Oxford, ensure that the protractor is aligned with the chart meridians and read off the bearing to the first waypoint — about 094° true.
• Centre the protractor on Warraway Mountain and read off the bearing to the second waypoint — about 061° true.
• Centre the protractor on the road junction and read off the bearing to Tottenham — about 040° true.
• Note that you can use the face of the protractor shown on the left as an erasable drawing surface.
• Using a scale ruler to measure the length of each route segment we find they are 74, 52 and 33 nm respectively.
engine performance a cruise altitude, where the throttle is fully open and the engine is delivering 65%–75% power, is indicated.
Before we can proceed further we must:
First light/last light; the official times for 'first' and 'last' light are purely a mathematical calculation and do not take into account diminution of light caused by terrain shadowing, cloud overcast, haze or mist. In southern Australian winter conditions it may be advisable that lengthy VFR flights should be planned to conclude at least one hour before the official last light.
Airservices Australia provides an online forecast service for 30 or so aviation forecast areas — ARFORs — shown on the PCA. First we need to locate our flight area on the PCA — outlined in green on the PCA section shown and thus located in ARFOR 22.
The black grid on the PCA is the individual WAC coverage so our planned flight area (outlined in green) is more or less contained in WAC 3457 but we would certainly need to also take along WAC 3356 adjoining the northern edge of WAC 3457.
Weather forecasts, NOTAMs and other pre-flight information are downloadable from Airservices Australia's [AsA] NAIPS Internet Service [NIS], 'a multi-function, computerised, aeronautical information system. It processes and stores meteorological and NOTAM information as well as enabling the provision of briefing products and services to pilots and the Australian Air Traffic Control platform'. NIS is accessed through the internet with any web browser or access may be integrated within flight planning software. The Bureau of Meteorology provides all the weather products to the NIS. The old AIS/MET service is, or will be, discontinued.
You must register with AsA before you can access the NIS. You are required to create a 'user name' and a password. If you don't have an ARN or Pilot Licence Number leave that field blank, don't use your RA-Aus or other sport and recreational organisation membership number, it may conflict with someone's Aviation Reference Number. Download the NIS user documentation
When registered, you can log in; enter user name and password, and then click the required link. If you choose 'Area Briefing' you can select up to 5 briefing areas by clicking on the map or by entering the required areas or sub areas (4-digit codes) in the entry boxes, place a check in the 'Head Office Notam — summary' request box, enter the validity period and then click on the 'Submit' button. Alternatively, click on the Area Directory link to select any of the area or sub areas from the the directory list. An area briefing provides area meteorological information, NOTAM and meteorological information on aerodromes, NOTAM for restricted areas within the selected area, and relevant Flight Information Region meteorological and NOTAM information. The aerodrome meteorological information is in the form of Meteorological Reports [METAR] and Aerodrome Forecasts [TAF]. We will look at the meteorological information in the flight plan preparation module for which I have downloaded an area 22 ARFOR and added some comments (this opens in a new browser window).
Plain English conversions of current ARFOR, METAR and TAF for all Australian ARFOR areas are available from Ian Boag's website. However pilots must still get the NOTAM from the Airservices site. Also student pilots should be aware that the ability to decode the BOM information will be tested in some of the aviation examinations. Bear in mind that CAR 120 imposes penalties for use of forecasts that were not made with the authority of the Director of Meteorology or by a person approved for the purpose by CASA and it may be that plain English conversions are not authorised by the Director or CASA.
The times of first light and last light for any Australian location are accessed from the opening page — click 'First Light-Last Light'. Current UTC date and time may be derived with the 'Time Zone Converter (Local To UTC)'.
aviation weather services page. The colour images from the BoM's Weather Watch Radar Network indicate the intensity of atmospheric precipitation overlaid on a surface map for an area up to 512 km radius from the radar. The radar images are updated every 10 minutes or so and the latest four images can be rolled into a progressive display that gives an indication of the development and velocity of such weather phenomena. The weather radars provide the most accurate and up-to-date rain and storm information, and should always be checked prior to a flight within areas covered by the radars. Lightning trackers such as Weatherzone provide useful information on current storm location and movement.
Online learning' page in the Education section. Each tutorial topic takes 5–10 minutes to complete and the whole tutorial can be completed at your own pace.
OnTrack is a series (currently 12) of online, interactive guides to VFR operations in and around controlled airspace associated with six Class D general aviation aerodromes plus six Class C CTRs. They are accessible from the 'OnTrack' page in the Education section.
OnTrack features interactive maps with added visual terminal chart (VTC) information utilising video, audio, pop-up alerts and text. OnTrack is not of much interest to most RA-Aus pilots because, unlike the Visual Pilot Guides, the Class C and Class D bypass routes don't seem to be included (yet?).
Five Visual Pilot Guides are accessible from the 'Visual Pilot Guides' page in the Pilot guides & information section, the last revision was 13 December 2010. These publications are pdf format guides to VFR operations near Australia's major cities. The main purpose is to facilitate route planning into or from the Class D general aviation aerodromes — which is not of much interest to most RA-Aus pilots. However the guides also help familiarise recreational aviators with the recommended VFR routes, altitudes and VHF frequencies that provide safe navigation around and under the Class C and Class D airspace steps, military control zones and restricted areas.
CASA's Visual Flight Rules Guide (November 2011 version) is now only available in pdf format, downloadable in six sections and accessible from the Pilot guides & information section.
Safety-related videos may be viewed at the CASABriefing YouTube channel.
|Stuff you don't need to know
• DR was born in the early days of oceanic sailing vessels. Every hour or two during the voyage the log (a quadrant shaped piece of wood weighted to float upright with an attached log-line knotted at intervals) was dropped over the stern of a vessel under way and the vessel's speed was reckoned from the amount of line paid out over a particular period of time. In 1637 an English mathematician and navigator, Richard Norwood, calculated that the spacing between knots should be 47.25 feet with a 28 second sand glass used as the timer. If you do the calculation, using the then estimated 6075 feet to the nautical mile, you will see that the number of knots that passed over the stern rail during the 28 second period equals the ship's speed in nautical miles per hour — hence knots. The log was presumed to be 'dead in the water'; i.e not dragged by the ship or affected by tide, drift or current. Each reading was marked on a log-slate and, during each watch, the course, speed and distance reckonings — adjusted for tide and current estimates — were entered in the logbook.
(Note: some obviously non-nautical people reckon that 'dead reckoning' is a diminutive of 'deduced' reckoning, but I reckon their reckoning is wrong. According to the Oxford English Dictionary the term 'dead reckoning' first appeared in print in 1613 in a work titled 'Magnetic Bodies' written by one M. Ridley; so the term has been in use for at least four centuries. The term also appeared in Richard Norwood's work, The Seaman's Practice, published in 1637.)
Groundschool — Flight Planning & Navigation Guide
|Module 4 of the Flight Planning & Navigation Guide discusses the effects of wind on heading and groundspeed|
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