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VHF radiocommunications

Radiotelephony communications and procedures
in Class G airspace


Rev. 26c — page content was last updated 25 July 2014 to incorporate AIP Book 21 August 2014 changes.
  
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Transmissions from aircraft stations operating in Class G airspace are generally of three types. The first is an advisory broadcast (for which an acknowledgement is not expected) when — for traffic separation purposes — a pilot informs the other stations in the vicinity who are listening-out, of her/his whereabouts and intentions. The second type is a station-to-station call, where a pilot requests specific information from the Airservices Australia flight information service, another aircraft station or an aerodrome ground station. The third type is a response to another aircraft or ground station where specific information is supplied in response to a request, or in response to an advisory broadcast when a potential traffic conflict is perceived.

Most transmissions by aircraft in Class G will be made when in the vicinity of non-controlled airfields and usually in the form of broadcasts made in accordance with the requirement (stated in CAR 166C) that pilots 'must make a broadcast ... whenever it is reasonably necessary to do so to avoid a collision, or the risk of a collision, with another aircraft ...' operating in the vicinity. Transmissions to avoid collision, or the risk of a collision, are mandatory. Other broadcasts are discretionary, but their format should conform with a standard broadcast structure.


Note: in the AIP Book, the term 'should' implies that users are encouraged to conform with the procedure, whereas the imperative term 'must' (or 'shall') means that the procedure is mandatory. All procedures/requirements defined as mandatory within AIP are (or should be) supported by CARs or CAOs.

To minimise frequency congestion it is desirable that transmissions are kept to the minimum, both in application and in content, and that 'aviation English' is used. But bear in mind that dissemination of important safety information is vital. Pilots must judge when and what transmissions should be made in the interests of both safe, expeditious traffic flow and minimum frequency congestion. All transmissions must be short but understandable, bearing in mind that Australian idiom may not be comprehensible to all persons receiving the transmission. Be aware the Australian flight training industry attracts many students from overseas and all pilots should do what they can to support that industry and its students.


      Content


5.1 Communications in the vicinity of airfields in Class G airspace

Common traffic advisory frequencies
If a public-use non-controlled* aerodrome has a reasonable number of daily movements Airservices Australia assigns a discrete VHF frequency to that site, which all aircraft should (not must, see AIP ENR 1.1 para 21.1.14.1) monitor when operating in the vicinity of that airfield.
  • This discrete frequency is known as the common traffic advisory frequency or CTAF (see-taff) and is shown in the ERSA entry for that location and is also depicted on the VNC, VTC and ERC-L aeronautical charts – next to the airfield ID as 'CTAF frequency'; e.g. 'CTAF 118.6'.

  • However, if an airfield or a private airstrip is depicted on the VNC, VTC, ERC-L or WAC aeronautical charts, without a discrete CTAF being shown, then the default 'Multicom' frequency of 126.7 MHz should be used.

  • The larger 'broadcast areas' are defined airspace volumes in Class G airspace for which a discrete CTAF has been allocated. (That discrete CTAF could be 126.7 MHz.) All operations, including those at aerodromes (charted or uncharted) and any landing ground, within this area shall use that CTAF as the broadcast frequency. See AIP Book ENR 1.4 section 3.2. Broadcast area lateral boundaries are shown on the aeronautical charts with a note stating "For operations in this area SFC – (altitude) use CTAF (frequency)". The area around the Avalon, Vic control zone is an example. The lateral and vertical limits are defined on the charts; the default vertical limit is 5000 feet amsl.

  • In all other cases the flight information area frequency should be used at non-controlled aerodromes or landing grounds.

*Note: the Civil Aviation Regulations define and use the term 'non-controlled aerodrome', however Airservices Australia's AIP book has been erroneously using the USA term 'non-towered aerodrome' for some time (the term is or was also used in some advisory publications) but, as the 'non-towered aerodrome' term is not yet supported by legislation, all references were deleted from AIP or replaced by 'non-controlled aerodrome' effective 21 August 2014.

CARs 166, 166A, 166B, 166C, 166D and 166E establish the regulatory environment for operations at non-controlled aerodromes.

If an aerodrome air traffic control tower does not maintain a 24-hour 7-day service CAR 166D allows CASA to classify any of those aerodromes as a designated non-controlled aerodrome during the periods when the control tower is unmanned. The 'designated' term prescribes mandatory carriage and use of radio on the airfield frequency.

CAR 166C defines the responsibilities and mandatory actions for broadcasting on VHF radio when operating in the vicinity of a non-controlled aerodrome. When planning a flight into an airfield not listed in ERSA, it is advisable to check the frequency being used with the airfield owner/operator — there are unlisted landing areas where a dedicated airfield frequency, other than the multicom 126.7 MHz , may still exist but is not shown on the aeronautical charts; see specific frequencies. This particularly applies to airfields supporting glider operations. CTAFs are usually not monitored by Air Traffic Services.

An aircraft is 'in the vicinity' of a non-controlled aerodrome if it is within a horizontal distance of 10 nautical miles from that aerodrome and at a height above the aerodrome that could result in conflict with operations at the aerodrome. The height dimension of the aerodrome's airspace is a rather nebulous concept — few light aircraft pilots would be familiar with the potential flight path profiles of fast-moving RPT aircraft conducting their normal 'straight-in' or 'circling' approaches or their climb-out; so the upper and lower 'vicinity' limits (at various distances from the airfield with allowance for terrain elevation) are difficult to judge. Perhaps 5000 feet amsl could be regarded as the height limit of the airspace at most CTAF aerodromes – but aerodrome elevation must be taken into account.

The 10 nm radius of the 'vicinity' encloses more than 1000 square kilometres of territory which is likely to contain other airfields, private airstrips (and paddocks) used for recreational operations and agricultural work, any of which may, or may not, appear in ERSA or other airfield guides. When aerodromes are in close proximity they are usually allocated the same CTAF, but that is not always so and only the pilot can judge the best time to make the appropriate frequency changes when operating in the vicinity of more than one landing area.

CAR 166E requires that, if the aerodrome listing shown in ERSA FAC describes the airfield as 'CERT' or 'REG' or 'MIL' or is a 'designated non-controlled aerodrome'*, then the carriage and use of VHF radio — confirmed to be functioning on the designated frequency — is mandatory for all aircraft operating in the vicinity and, of course, the pilot of an RA-Aus aircraft must hold a RA-Aus radio operator endorsement. There are about 300 such civilian certified or registered airfields in Australia, all of which usually have scheduled regional RPT movements. I have compiled a listing in text file format of those CASR Part 139 certified aerodromes [184] and registered aerodromes [120] but it will not reflect current status, so check ERSA. Carriage of VHF radio is usually not mandatory within the vicinity of the other non-controlled airfields — unless a temporary notam is current — though highly recommended. But all radio-equipped (hand-held or fixed installation) aircraft must maintain a listening watch and must be prepared to broadcast on the CTAF or the Multicom frequency 126.7 MHz.

*Note: prior to about 2006 'designated non-controlled aerodromes' were commonly known as 'CTAF(R)s'; in the 1990s they were 'MBZs' – mandatory broadcast zones.

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-controlled aerodromes. These Civil Aviation Advisory Publications (available on this website) are: CAAP 166-1 'Operations in the vicinity of non-controlled aerodromes' (August 2014) and CAAP 166-2 'Pilots responsibility for collision avoidance in the vicinity of non-controlled aerodromes using 'see and avoid' (December 2013).

Note that the 'ultralight' term as 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 (i.e. non-controlled) aerodromes' which is now available at CASA online learning.

About 100 Australian aerodromes are equipped with an Aerodrome Frequency Response Unit [AFRU] or 'bleepback' — a device that transmits an automatic aural response when a pilot transmits on the CTAF, thus confirming that the pilot is on the correct airfield frequency. AFRU features are explained in AIP GEN 3.4 sub-section 3.4.
Accessing AIP Book and ERSA
Airservices Australia publishes online versions of the AIP Book, SUPS, AICs and ERSA at www.airservicesaustralia.com/publications/aip.asp (click the 'I agree' button to gain entry). To find a particular section of AIP or ERSA you have to click through a number of index pages. The section/subsection/paragraph numbering system was designed for a readily amendable looseleaf print document, so you may find it a little confusing as an online document.
Unicom services
Any Unicom (universal communications) service that exists would be a private non-ATS aeronautical station licensed by ACMA that may provide — on pilot request — basic wind, weather and perhaps some traffic advisory information in plain language, but certainly not a traffic separation service. Unicom may be provided by the aerodrome operator, the local refueller or an airline representative during RPT operational periods. Any Unicom facility and call-sign would be indicated in ERSA. Refer to AIP GEN 3.4 sub-section 3.3.

The advantage of Unicom to recreational pilots may be that the service (if it operates on the CTAF) provides some additional information and thereby confirmation of the correct frequency selection and operation of the radio. Unicom communications always take second place to pilot-to-pilot communications on the CTAF.
Certified air/ground radio services [CA/GRS]
In 2011 there remained just one non-towered aerodrome operator (Ayers Rock) providing a 'certified' ground-to-air radio information service on the CTAF to all aircraft operating in the vicinity. This service is usually provided where, and when, there is significant RPT traffic. They are not an Airservices Australia sponsored service but the radio operators 'have been certified to meet a CASA standard of communication technique and aviation knowledge appropriate to the services being provided.'

For recreational aviation the service is similar to a Unicom service but the CA/GRS operator will most likely provide better traffic information. For more details read AIP GEN 3.4 section 3.2. Operating times, call signs and any special procedures will be shown in the aerodrome ERSA entry.

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5.2 Radio procedures at non-controlled airfields

Communication requirements when operating in the vicinity of a non-controlled aerodrome are defined in AIP Book ENR 1.1 section 21 table 'Summary of broadcasts - all aircraft at non-controlled aerodromes'.

The following seven broadcasts are 'recommended', meaning that the operational decisions regarding their use are then properly left to the pilot. The pilot is expected to conduct operations in an airmanlike manner in accordance with the existing environment and traffic conditions. There may be requirements detailed in the ERSA entry for a particular airfield that vary from the standards detailed below. Some temporary variation in the following procedures may also be stipulated, via NOTAM or AIP supplement, for special events; e.g. the annual Birdsville Race meeting or the RA-Aus Easter weekend national fly-in at Temora.
Arrival and transit advisory broadcasts
VFR aircraft reaching the vicinity of an aerodrome within Class G airspace, and intending to land, must monitor the designated airfield frequency (otherwise the multicom frequency) and should make these broadcasts on that frequency:
  • an inbound broadcast — by 10 nautical miles from the airfield
  • a joining circuit broadcast immediately before joining the circuit
  • if making a straight-in approach, broadcast on final approach not less than 3 nm from the threshold
  • if joining on base leg, broadcast joining base leg prior to joining on base.
(Note: straight-in approaches and joining the circuit on the base leg, though acceptable, are not recommended procedures.)

If intending to operate in the vicinity of an aerodrome, rather than land, the aircraft must monitor the appropriate frequency and broadcast:
  • (a) if in transit, an overflying report — by 10 nm from the airfield.
  • (b) if operating from a private airstrip less than 10 nm from the aerodrome, an intentions report once airborne.
Regulations recommend a transit report if the flight path passes in the airfield vicinity at a height that 'could result in conflict with operations'. A high-performance aircraft departing from an airfield could attain 5000 feet agl before reaching the 10 nm boundary so caution would dictate a transit report advisable even if cruising altitude is above 5000 feet agl — and an airfield should not be overflown at any height less than 3000 feet agl. If you don't hear or see any other traffic in the area do not assume there is none and neglect to make any calls.
Departure advisory broadcasts
All aircraft operating from a non-towered aerodrome must monitor the airfield CTAF and should make the following broadcasts on that frequency:
  • immediately before, or during, commencing taxiing to the runway, make a taxiing broadcast
  • broadcast immediately before entering runway.
Broadcasts within the circuit
The AIP no longer defines any mandatory or recommended broadcasts such as 'turning downwind', 'turning base', 'turning final' or 'clear of runway'. Instead CAR 166C states: 'The pilot must make a broadcast ... whenever it is reasonably necessary to do so to avoid a collision, or the risk of a collision, with another aircraft ...'

A turning final broadcast should be regarded as mandatory. It is often difficult to see a stationary aircraft, vehicle or even line marking operators on the runway, let alone an aircraft on a straight-in approach. Most mid-air collisions occur on approach where a faster aircraft descends upon the aircraft in front (see 'Further online reading') and collisions do occur on runways after landing. The turning final call does provide a warning at a time when the aircraft turning is most visible.

The necessity for a turning base or other circuit call are matters of judgement that depend upon the amount and type of traffic, separation and flow. The more ordered it is the fewer the calls needed. On the other hand, if there are no other aircraft heard or seen in the circuit then there will be minimum chance of frequency interference or frequency congestion — and it will be safer — if every possible call is made.

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5.3 Prescribed CTAF broadcast formats

All VFR broadcasts from an aircraft station in Class G are quite simple, having much the same content presented in much the same sequence:
  1. The location
  2. Who I'm calling
  3. Who I am
  4. Where I am
  5. What my intentions are
  6. The location repeated
Expressed in the official manner:
  1. Location (The general area, usually an airfield name)
  2. Called station/s ID (Who I'm calling)
  3. Calling station ID (Who I am; i.e. aircraft type and registration)
  4. Calling station position (Where I am, usually in reference to the airfield)
  5. Calling station intentions (What my intentions are)
  6. Location repeated
For a broadcast transmission there is no specific station being called; you are just addressing all those aircraft stations (and possibly ground stations) in the vicinity who are maintaining a listening watch on the CTAF. The called station ID is usually "TRAFFIC" and presumably this is meant to include ground aeronautical stations and aeronautical mobile stations, rather than just aircraft stations.

If you are making a broadcast call where you are asking a question and hope for a response then the called station ID would be "ANY STATION" or "ANY TRAFFIC" preceded by the location name.

The calling station ID is the aircraft call-sign which, for RA-Aus aircraft, already includes the aircraft type. For a General Aviation aircraft the calling station ID is the three-letter aircraft registration, so the aircraft type must be added; e.g. PIPER WARRIOR/ALPHA YANKEE CHARLIE.

In the following example broadcasts the location is 'TANGAMBALANGA' and the aircraft call-sign is 'THRUSTER ZERO TWO EIGHT SIX'.
Taxiing call format
The taxiing call notifies all aircraft that you are about to taxi to a runway, and particularly alerts any other ground traffic that is taxiing to or from a runway to be vigilant for traffic movements.
  1. [location] TRAFFIC
  2. CALL-SIGN
  3. TAXIING RUNWAY (number)
  4. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • TAXIING RUNWAY TWO FIVE
  • TANGAMBALANGA
Entering runway call format
The 'entering runway' call alerts any traffic in the circuit or clearing the runway that you are about to use the runway for take-off. The call particularly alerts aircraft on base leg or straight-in approach to be prepared to go around in the event that there is a conflict.
  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. ENTERING RUNWAY (number)
  4. (Intentions or the departure quadrant)
  5. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • ENTERING RUNWAY TWO FIVE (or ENTERING AND BACKTRACKING RUNWAY TWO FIVE)
  • FOR CIRCUITS or DEPARTING TO THE SOUTH
  • TANGAMBALANGA

Aircraft should remain at the runway holding point until all checks are complete and the runway and the approach are seen to be clear — then make the ENTERING RUNWAY broadcast. If there has been a significant delay between the entering runway broadcast and commencement of take-off then a ROLLING call may be helpful to aircraft on the approach. The format would be the same as the entering runway call but with the word ENTERING replaced with ROLLING. If you decide to abandon the take-off after entering the runway then broadcast ABANDONING TAKE-OFF plus your intentions regarding vacating the runway. If you intend taxiing to an exit keep to the left of the runway — just in case!
Inbound call format
  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. (Position — reported as the distance and the compass quadrant from the aerodrome) (altitude)
  4. (Intentions)
  5. Location repeated
For example:
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • ONE TWO MILES NORTH-EAST / TWO THOUSAND FIVE HUNDRED
  • INBOUND or INBOUND FOR A STRAIGHT-IN APPROACH RUNWAY TWO FIVE
  • TANGAMBALANGA
Straight-in approaches are acceptable but not recommended. If you intend to make a straight-in approach that intention should be included in the initial inbound broadcast.

Some aircraft may report their position in terms of magnetic bearing from the airfield or the VOR radial. Such information is officially acceptable but the compass quadrant format is advisable, being readily understood by all and quite sufficient to alert other aircraft.

Note that the word 'altitude' does not precede 2500; the figures are unlikely to be confused with anything else. Do not precede the altitude figures with the word 'AT' — which is reserved to specify time. When on descent the altitude might be expressed as 'DESCENDING THROUGH (altitude)'; e.g. 'ONE TWO MILES NORTH-EAST / DESCENDING THROUGH FOUR THOUSAND FIVE HUNDRED'. Also note that we have transmitted the location twice, which is always required as there may be several airfields within range on the same frequency, and doubling up the name helps to clarify the transmission. If the airfield name is short, or similar to another airfield within range (say 60 nm), then additional mention of the location may be appropriate; as in the following:
  • BOURKE TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • ONE THREE MILES NORTH-EAST BOURKE / TWO THOUSAND FIVE HUNDRED
  • INBOUND
  • BOURKE
If your groundspeed is low and it will take some time to reach the circuit area it may be advisable to add your estimated time of arrival to the intentions. If so, it is conventional for the time to be expressed in minutes past the hour, in which case the previous call might be: 'INBOUND ESTIMATE BOURKE AT FOUR FIVE'. If you estimate your arrival will be near enough to the hour then the call would be 'INBOUND ESTIMATE BOURKE ON THE HOUR'.

Don't forget aviation times are UTC so the minutes in local time do not coincide with the minutes in UTC when the time difference in the area includes a half-hour — Central (Australia) Standard Time, for example. In such instances it may be advisable to append the word 'ZULU' to the time in UTC minutes — or best use the local time and append the term 'LOCAL TIME' to the message; i.e. 'INBOUND ESTIMATE BOURKE ON THE HOUR LOCAL TIME'.
Transit call format
  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. (Position — reported as the distance and the compass quadrant from the aerodrome) (altitude)
  4. (Intentions)
  5. Location repeated
For example:
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • ONE TWO MILES SOUTH TANGAMBALANGA / MAINTAINING THREE THOUSAND FIVE HUNDRED
  • OVERFLYING TO THE NORTH
  • TANGAMBALANGA
The broadcast indicates the intent to maintain 3500 feet while overflying the area on the way north.
Joining circuit call format
  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. JOINING (position in circuit – upwind, crosswind or downwind) (location) (runway)
  4. (Intentions)
  5. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • JOINING DOWNWIND RUNWAY ZERO SEVEN
  • TANGAMBALANGA
It is only necessary to state intentions if you are not intending to land and turn off the runway. If you are intending to do a few circuits first then the transmission is:
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • JOINING CROSSWIND RUNWAY ZERO SEVEN
  • FOR CIRCUITS (or 'FOR TOUCH-AND-GO' if you don't intend to turn off the runway)
  • TANGAMBALANGA
Final approach report format for straight-in approaches
The 'final approach' call must be made at not less than 3 nm from the runway threshold.

  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. FINAL APPROACH (runway)
  4. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • FINAL APPROACH RUNWAY ZERO SEVEN
  • TANGAMBALANGA
or
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • FINAL APPROACH RUNWAY ZERO SEVEN
  • BACKTRACKING AFTER LANDING
  • TANGAMBALANGA
Clear of runway call format
This call that you have turned off the runway particularly helps where a rise in the runway obscures the view of an aircraft preparing to take-off.
  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. CLEAR OF RUNWAY (runway number)
  4. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • CLEAR OF RUNWAY ZERO SEVEN
  • TANGAMBALANGA
Turning downwind call format
Although not mentioned in AIP the following 'in-circuit' broadcasts may be made if the circuit traffic situation warrants use of any of them.

A 'turning downwind' call could be made when starting the turn onto the downwind leg — if the circuit was joined crosswind or if the aircraft is doing touch-and-goes.

  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. TURNING DOWNWIND (runway)
  4. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • TURNING DOWNWIND RUNWAY ZERO SEVEN
  • TANGAMBALANGA
Turning base call format
The 'turning base' call should be made when starting the turn onto base, as it provides a more precise location for sighting and a banked aircraft is more visible.

  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. TURNING BASE (runway)
  4. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • TURNING BASE RUNWAY ZERO SEVEN
  • TANGAMBALANGA
If you are doing a right-hand circuit it is advisable to say so in the transmission, for example 'TURNING RIGHT BASE'.
Turning final call format
The 'turning final' call should be made when starting the turn onto final.

  1. (Location) TRAFFIC
  2. CALL-SIGN
  3. TURNING FINAL (runway)]
  4. (Intention)
  5. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • TURNING FINAL RUNWAY ZERO SEVEN
  • TOUCH-AND-GO
  • TANGAMBALANGA
If you are doing circuits then you should add the intention 'TOUCH-AND-GO'; or if this is the last landing of a session of touch-and-go circuits then "FULL STOP' so that any following aircraft doing circuits-and-bumps can make the allowance for runway separation.
Broadcast etiquette
There are a few unwritten rules that greatly aid understanding by those maintaining a listening watch on the frequency:
  • First ask yourself; "Is this call really necessary?"

  • Mentally compose your message using aviation English (but no jargon), before operating the press-to-talk switch, thus avoiding a transmission containing 'umms' or 'aahs' or long pauses. Transmit once and transmit succinctly!

  • Listen out for a second or two before transmitting so that you don't broadcast over someone else.

  • Ensure you operate the press-to-talk switch before you start speaking; otherwise you are going to cut off the first word or part of it, probably making the broadcast useless to others. This is particularly so because the first word of the transmission is required to be the location.

  • Speak distinctly and at a normal level (speaking loudly will distort the transmission) and at a normal pace (no-one appreciates a clipped, rapid-fire broadcast from the would-be 'hot-shot' pilot); and don't run the words together. Usually the microphone is designed to be squarely in front of the lips and 1–3 cm from them.

  • Ensure the transmission system is of reasonable quality, properly maintained and operated in accordance with the manual.

  • Avoid using superfluous words like 'IS taxiing', 'IS entering' or 'TRACKING for Holbrook' or 'PLEASE' or 'THANKS'. The term 'tracking' is usually only associated with a VOR radial or magnetic track; e.g. TRACKING ZERO TWO ZERO.

  • Don't use non-aviation English phrasing such as '(call-sign) TURNS base' instead of '(call-sign) TURNING base'. Such phrasing is confusing — particularly to students — and may grate on other listeners; consequently the listener may not absorb the information and the broadcast has no value. Avoid confusion and annoyance!

  • Ensure you are not inadvertently transmitting because of a stuck microphone switch. It is very annoying to others, possibly adding to stress and detracts from airfield safety . It can be extremely embarrassing to yourself, and perhaps costly, if you happen to be transmitting the cockpit conversation.

  • Listen carefully to any message being transmitted so that you fully understand it.

  • If you don't understand a transmission ask for a repeat — AIRCRAFT CALLING SAY AGAIN.

  • And remember your own transmission must not include:
    • profane or obscene language
    • deceptive or false information
    • improper use of another call-sign.
And do not attempt to avoid landing fees by sneaking in without using the radio. Such actions are stupid but may be criminally reckless.

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5.4 Discretionary broadcast formats

Although radio calls should be kept to a minimum, there are times when traffic circumstances indicate some extra or discretionary calls would be helpful to all in maintaining safe separation; or when you do something unusual such as a go-around or back-tracking after landing. Discretionary calls may be shorter than standard calls.
Going around call format
If it is necessary to abort the landing and conduct a go-around, a broadcast may be helpful to others.
  1. (location) TRAFFIC
  2. CALL-SIGN
  3. GOING AROUND (runway number)
  4. Location repeated
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • GOING AROUND / RUNWAY ZERO SEVEN
  • TANGAMBALANGA
If the go-around was necessitated by something that may affect other aircraft then add information to the broadcast; e.g.
  • GOING AROUND / RUNWAY ZERO SEVEN OBSTRUCTED BY LIVESTOCK
Departure call format
If, for example, you had been practising touch-and-goes and are now leaving the circuit it may be helpful to other aircraft to inform them of your intentions to depart the circuit.
  1. [location] TRAFFIC
  2. CALL-SIGN
  3. DEPARTING (runway) (turn) (departure quadrant)
  4. Location repeated
For example:
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • DEPARTING FOR HOLBROOK
  • TANGAMBALANGA
There is a possibility that the word 'TO' might, in some circumstances, be confused with the numeral 'TWO' — or the word 'FOR' be confused with the numeral 'FOUR' — so some care is needed when composing a transmission.
Requesting information
There are occasions when a request for information from other aircraft is appropriate. For example, when approaching an airfield and no traffic has been heard on the airfield frequency but you would like to know what runway is in use — possibly by non-radio aircraft. In this case use the call ANY STATION (location) thus:
  • ANY STATION TANGAMBALANGA
  • THRUSTER ZERO TWO EIGHT SIX
  • REQUEST RUNWAY IN USE TANGAMBALANGA
The response from a general aviation aircraft on the ground or in the circuit might be:
  • THRUSTER ZERO TWO EIGHT SIX
  • ALPHA YANKEE CHARLIE
  • TANGAMBALANGA RUNWAY ZERO SEVEN IN USE
And the acknowledgment:
  • RUNWAY ZERO SEVEN
  • THRUSTER ZERO TWO EIGHT SIX

5.5 Communicating with Unicom or CA/GRS stations

When inbound to an airfield with a Unicom or CA/GRS service, an information request might take this form (the Unicom call-sign is generally the location plus 'UNICOM'; the CA/GRS call sign will be location plus 'RADIO'):
  • TANGAMBALANGA UNICOM
  • THRUSTER ZERO TWO EIGHT SIX
  • ONE FIVE MILES SOUTH-EAST INBOUND FOR LANDING
  • REQUEST WIND AND TRAFFIC INFORMATION TANGAMBALANGA

The informal response from the ground operator might be:
  • "THRUSTER ZERO TWO EIGHT SIX — TANGAMBALANGA UNICOM — WIND IS ZERO SIX ZERO AT TEN KNOTS — A WARRIOR IS DOING CIRCUITS AND A DASH EIGHT INBOUND FOR A STRAIGHT-IN APPROACH ON ZERO SEVEN"
There is no requirement to read back any of the information communicated but without a reply the ground operator is left wondering, so the acknowledgment:
  • ROGER
  • THRUSTER ZERO TWO EIGHT SIX

Before taxiing at an airfield with an Unicom or CA/GRS service an information request might take this form:
  • TANGAMBALANGA RADIO
  • THRUSTER ZERO TWO EIGHT SIX
  • REQUEST WIND AND TRAFFIC INFORMATION TANGAMBALANGA

The response from the ground operator might be:
  • THRUSTER ZERO TWO EIGHT SIX — TANGAMBALANGA RADIO — WIND IS ZERO FIVE ZERO ABOUT FIVE KNOTS — NO KNOWN TRAFFIC
And the acknowledgment:
  • ROGER
  • THRUSTER ZERO TWO EIGHT SIX
Thruster 0286 would then make a taxiing broadcast when appropriate.

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5.6 CTAF response calls

The difficulty for an inexperienced pilot is what to do — and say — in response to a broadcast from another aircraft that is perceived as a possible traffic conflict; particularly in an environment when high-speed turbo-prop RPT aircraft are operating.

Maintaining situation awareness is a must for all pilots. All pilots must be aware of the positions and intentions of all other traffic in the vicinity, and — to determine possible traffic conflicts — able to project the likely movements of such traffic. This is not easy for anyone, particularly so if insufficient information is being provided. This is aggravated when aircraft are conducting straight-in approaches, so extra vigilance must be maintained, remembering the straight-in approach may be on the longest runway rather than the into-wind runway — or it might even be an 'opposite direction' landing.

You must maintain a mental plan of the runways and associated circuit patterns, and overlay that with the current positions and announced intentions of other traffic. You must include the possibility of abnormal events; e.g. where is the missed-approach path for the turboprop aircraft currently on a straight-in approach on the longest runway? And you must keep other traffic informed of your intentions.

Caution. When something unexpected happens in the circuit, for example a broadcast from another aircraft indicates you may be on a collision course, then naturally you will swivel around to locate the other aircraft. In these conditions there is a tendency to be distracted from flying the aeroplane — a dangerous position when at low speed and low altitude, particularly so if turning base or final. See 'Don't stall and spin in from a turn'.

Although a recreational aircraft may have the right of way in a particular traffic situation, it is environmentally positive, courteous and good airmanship for recreational pilots to allow priority to RPT, agricultural aircraft, firefighting and other emergency aircraft, or for that matter any less-manoeuvrable heavy aircraft.

The following is an example transmission from an aircraft on downwind which, after making a downwind broadcast, has monitored a straight-in approach call from an RPT turboprop and is now advising all traffic of the intent to extend its downwind leg and then follow the turboprop in — at a safe interval to avoid wake turbulence.
  • TANGAMBALANGA TRAFFIC
  • THRUSTER ZERO TWO EIGHT SIX
  • EXTENDING DOWNWIND / RUNWAY ZERO SEVEN
  • NUMBER TWO TO SAAB ON STRAIGHT-IN APPROACH
  • TANGAMBALANGA
An article — Talk Zone— in the May–June 2001 issue of CASA's Flight Safety Australia discusses CTAF radio procedure problems. Substitute 'CTAF' for the 'MBZ' references in the article.

5.7 En route procedures

Class G airspace
There are no mandatory reports for VFR aircraft operating en route in Class G airspace. Thus after departing the airfield vicinity, such aircraft are only required to maintain a listening watch on the 'appropriate frequency' and announce if in potential conflict with other aircraft — see AIP ENR 1.1 section 44.

"ALL STATIONS (location)" instead of "(location) TRAFFIC" may be used for the called stations ID (refer AIP ENR 1.1 para. 68.4); for example:
  • ALL STATIONS MAITLAND AREA
  • THRUSTER ZERO TWO EIGHT SIX
  • REQUEST ADVICE ON THE WEATHER CONDITIONS IN THE VFR LANE TO GLOUCESTER


So what's the 'appropriate' frequency? This could be:
  • the local Flight Information Area frequency — if so, calls to the Flight Information Service would be directed to Flightwatch which service is provided by either MELBOURNE CENTRE or BRISBANE CENTRE. If close to a major airport then perhaps (for example) SYDNEY RADAR. Frequency information blocks depicting Class E and G area frequencies, and the frequency boundaries, are included on the ERC-L, VNC and VTC charts.

  • a listening watch could be maintained on the International Distress Frequency 121.5. See 'Can it ever be appropriate to monitor 121.5 MHz en route?';

  • a listening watch could be maintained on other specific frequencies;

  • if below 3000 feet agl then perhaps listen out on Multicom 126.7 MHz ;

  • when passing in or near the vicinity of a non-controlled aerodrome the designated frequency (otherwise 126.7 MHz or the FIA frequency ) for that airfield should be monitored to gain information on area traffic.
Class E airspace
As in Class G there are no mandatory reports for VFR aircraft operating en route in Class E airspace. Such aircraft are only required to maintain a listening watch on the 'appropriate frequency' and advise any potential conflict to the aircraft involved or to ATC. The choice of frequency would be much the same as in Class G with the addition of the appropriate ATC frequency. The latter must be used to take advantage of the Radar Information Service usually available in Class E.

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5.8 Acquiring weather and other information in-flight

Airservices Australia's Air Traffic Service [ATS] and the Australian Bureau of Meteorology provide several means of obtaining a limited amount of weather and other information while airborne:
  • AERIS — the Automatic En Route Information Service network
  • ATIS — the Automatic Terminal Information Service at some aerodromes
  • AWIS — the Aerodrome Weather Information Service at some aerodromes.
  • FLIGHTWATCH — the on-request Flight Information Service [FIS] provided by ATS.
Further FIS information is contained in AIP GEN 3.3 section 2 and in the Flight Information Services section of ERSA GEN-FIS.
AERIS
AERIS is a network of 14 VHF transmitters that continually transmit routine weather reports for major Australian airports and a few other significantly sited aerodromes. Such information could be a guide to actual weather at airfields in the vicinity of those major airports. CASA has issued the following pilot guide showing the location of AERIS transmitters, the expected VHF coverage for aircraft at 5000 feet, the VHF frequencies and the aerodromes for which weather reports are available from each transmitter. See AIP GEN 3.3 section 2.8 and AIP GEN 3.5 section 7.4. More information will be found in ERSA GEN-FIS-1.

AERIS


ATIS
ATIS is provided on either a discrete COMMS frequency or the audio identification channel (NAV band between 112.0 and 117.975 MHz) of an aerodrome navigational aid — generally in a control zone, but again such information could be a guide to actual weather at other airfields in the vicinity. The availability and frequency of the ATIS is specified in the ERSA airfield data. The continuous information broadcast includes the runway in use, wind direction (degrees magnetic) and speed, visibility, present weather, cloud and QNH. See AIP GEN 3.3 section 2.7.
AWIS
Australian Bureau of Meteorology automatic weather stations [AWS] are located at about 190 airfields. All the stations are accessible by telephone and about 70 are also accessible by VHF NAV/COMMS radio. The access telephone numbers and the VHF frequencies of the AWS can be found by entering the 'Location information' page and downloading the pdf for the relevant state. The information is also available in the aerodrome facilities section of ERSA and in the ERSA MET section.

The AWIS uses pre-recorded spoken words to broadcast the current observations collected by the AWS — surface wind, pressure, air temperature, dew point temperature and rainfall. (For example, call 08 8091 5549 to hear the AWS aerodrome weather at Wilcannia, NSW.)

In both the ATIS and AWIS reports, wind direction is given in degrees magnetic. This is because they are associated with aerodrome operations where runway alignments are in degrees magnetic, and conformity makes the crosswind estimate easier. Wind direction in all the text-based meteorological reports and forecasts is given in degrees true.

At aerodromes where ceilometer and vismeter sensors are available, the AWIS will report cloud amount, height and visibility but the reliability of such observations is limited — the AWIS broadcasts the aerodrome weather derived from the AWS instrumentation and without any human input. The wind direction is expressed in degrees magnetic to the nearest 10°. Note that some of the VHF frequencies are in the NAV band; i.e. the broadcasts are on the airfield VOR frequency. More information is available in the MET section of ERSA online.
Flightwatch
Flightwatch is the call-sign of the on-request service — contained within Airservices Australia's FIS — which provides information of an operational nature to aircraft operating in Class G airspace. Whether Flightwatch is able to respond to an information request from an RA-Aus aircraft depends on workload and whether the requested information is readily available to the Flightwatch operator contacted — for example, the actual weather at the smaller airfields.

The Flight Information Areas and FIS frequencies are depicted in ERC-L.

An information request to Flightwatch should take the following form — note the Flightwatch operator may be managing quite a number of frequencies so the FIA frequency used (for example 119.4 MHz) must be included in the transmission:
  • BRISBANE CENTRE FLIGHTWATCH
  • THRUSTER ZERO TWO EIGHT SIX
  • ONE ONE NINE DECIMAL FOUR
  • REQUEST ACTUAL WEATHER LISMORE
Acquiring QNH
It is not mandatory for VFR aircraft to use the area QNH whilst en route. You may substitute the current local QNH of any aerodrome within 100 nm of the aircraft. Or, if the local QNH at the departure airfield is not known, you can — while still on the ground — just adjust the sub-scale so that altimeter reads the airfield elevation.

Local QNH of airfields within 100 nm of the route might be acquired from AERIS, ATIS or AWIS; otherwise, area QNH can be obtained from Flightwatch:
  • BRISBANE CENTRE FLIGHTWATCH
  • THRUSTER ZERO TWO EIGHT SIX
  • ONE ONE NINE DECIMAL FOUR
  • REQUEST QNH AREA TWO TWO

5.9 The Surveillance Information Service [SIS]

Class E Airspace diagramTransponder-equipped VFR aircraft operating in Class E or Class G airspace within the ATC radar coverage (the tan and green colours in the map approximate the lower level coverage) may request a no-cost radar/ADS-B information service [SIS] on the appropriate ATC frequency. (SIS was formerly known as the Radar Information Service [RIS].) The SIS is available to improve situation awareness by providing traffic information and position information or navigation assistance. VFR pilots may also request an ongoing 'flight following' service from SIS, so that ATC monitor your flight progress and can also help you avoid controlled airspace. The requested service will be provided subject to the controller's current workload — their primary responsibility is towards IFR aircraft — but there is usually no problem, particularly if you have filed a flight plan. Refer to AIP GEN 3.3 section 2.16 for the general procedure and remember that you still must comply with CAR 163A which states:

'Responsibility of flight crew to see and avoid aircraft
When weather conditions permit, the flight crew of an aircraft must, regardless of whether an operation is conducted under the Instrument Flight Rules or the Visual Flight Rules, maintain vigilance so as to see, and avoid, other aircraft.'


Position information and flight following request call format
  1. (Location) CENTRE
  2. CALL-SIGN
  3. (Altitude) (general vicinity) (destination)
  4. REQUEST POSITION INFORMATION AND FLIGHT FOLLOWING
It is probably advisable to make a short contact call first then when the 'go ahead' response is received send the message.
  • MELBOURNE CENTRE
  • THRUSTER ZERO TWO EIGHT SIX
  • THREE THOUSAND / VICINITY ROMSEY FOR POINT COOK
  • REQUEST POSITION INFORMATION AND FLIGHT FOLLOWING
RIS will ask you to 'squawk ident' and when your aircraft is identified will assign an unique transponder code plus the navigation information. When navigation assistance and flight following is no longer required advise SIS.

5.10 Sourcing frequency information

The FIS frequencies to be used in Flight Information Areas and the frequencies at airfields (plus NDB and VOR frequencies) are either contained in ERSA or shown on PCA, ERC-L, VNC and VTC charts. The following table summarises the communications information available from those sources.

    PCAERC-LVTCVNCERSA
VHF coverage at 5000 feettick                
VHF coverage at 10000 feettick                
HF network sector frequenciestick                
SIS frequencies     tickticktick    
Flightwatch frequencies     ticktickticktick
FIA boundaries     tickticktick    
FIS frequencies at airfields                 tick
Airfields where FIS contact possible from ground     tick            
Airfield Unicom frequencies                 tick
VOR/NDB frequencies and ID     ticktickticktick
CTAFs     ticktickticktick

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Groundschool — VHF Radiocommunications Guide

| Guide content | Abbreviations and acronyms |

| 1. Transmitter licensing | 2. R/T phrasing | 3. VHF characteristics and radio operation |

| 4. Microair 760 transceiver | [5. R/T procedures] | 6. Safety and emergency procedures |

| 7. Aviation Distress Beacons | 8. Understanding SAR services |


Next — safety procedures The next section of the VHF radiocommunications guide outlines safety and emergency procedures


Copyright © 2003–2014 John Brandon     [contact information]

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