Radiotelephony procedures
Rev. 15a — page content was last changed November 28, 2009
consequent to editing by RA-Aus member Dave Gardiner www.redlettuce.com.au
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Radiotelephony proceduresRev. 15a — page content was last changed November 28, 2009 consequent to editing by RA-Aus member Dave Gardiner www.redlettuce.com.au |
| VHF radiocommunications | |
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Transmissions from aircraft stations operating in Class G airspace are generally of three types. The first is an information broadcast, for which an acknowledgement is not expected, where — for traffic separation purposes — a pilot informs all other stations in the vicinity, of her/his whereabouts and intentions. The second type is a station-to-station call, where a pilot requests specific information from another aircraft station or a 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 a 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 in the form of broadcasts made as part of the requirement that pilots take all reasonable steps to ensure that they do not cause a danger to other aircraft being operated in the vicinity of the aerodrome. Many of these transmissions are mandatory and regulations dictate their timing, content and structure. Other transmissions are discretionary but the format should conform with the standard broadcast structure. 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 remember: INFORMATION DISSEMINATION IS VITAL FOR SAFE FLIGHT OPERATIONS. Before proceeding further with this module it is advisable to read the CASA draft Advisory Circular AC 91-220(0) 'Operations at non-controlled airfields'. Note: the term 'non-controlled' aerodrome or airfield is synonymous with 'non-towered'. |
5.1 Operations in the vicinity of airfieldsCommon traffic advisory frequenciesThose public-use non-towered aerodromes that have a reasonable number of daily movements are assigned a particular VHF frequency (by Airservices Australia), on which all aircraft make positional broadcasts when operating in the vicinity of that airfield. This designated frequency is known as the common traffic advisory frequency or CTAF (see-taff) and is shown in the ERSA entry for that location. The frequency is also on VNC, VTC and ERC-L charts next to the airfield ID, shown as 'CTAF frequency'; for example 'CTAF 118.6'.An aircraft is 'in the vicinity' of a non-towered aerodrome if it is within a horizontal distance of 10 nautical miles; and within a height above the aerodrome that could result in conflict with operations at the aerodrome. Carriage of VHF radio is usually not mandatory within the vicinity of a non-towered aerodrome — though highly recommended — but all radio-equipped (hand-held or fixed installation) aircraft, including ultralights, must make the prescribed broadcasts on the CTAF. If the CTAF shown in ERSA or on the charts is followed by (R), for example CTAF 118.6 (R), then the carriage and use of VHF radio — confirmed to be functioning on the designated frequency — is required for all aircraft operating in the vicinity. There are fewer than 100 CTAF (R) airfields in Australia, all of which usually have scheduled regional RPT movements. 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. If operating in the vicinity of any airfield within Class G airspace that does not have a designated CTAF, then the default Multicom frequency 126.7 MHz should be used; the Flight Information Area [FIA] frequency must not be used. When planning a flight into an airfield not listed in ERSA, it is advisable to check the frequency being used with the airfield operator — there are unlisted airfields where a dedicated airfield frequency, other than 126.7 MHz , still exists; see specific frequencies. This particularly applies to airfields supporting glider operations. Unicom servicesAny Unicom service that exists would be a private 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, operating on the airfield frequency, 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 2006 there were just two non-towered aerodrome operators (Broome and Ayers Rock) providing a 'certified' ground-to-air radio information service on the CTAF(R) 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 sub-section 3.2. Operating times, call signs and any special procedures will be shown in the aerodrome ERSA entry. |
5.2 Prescribed radio procedures at non-towered airfieldsCommunication requirements when operating in the vicinity of a non-towered aerodrome are defined in AIP ENR 1.1 sections 56 to 65 — "Operations in Class G airspace". These only relate to mandatory broadcasts and 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.If you don't hear or see any other traffic in the area do not assume there is none and neglect to make your mandatory calls — or even the discretionary calls referred to in 'Discretionary broadcast formats'. The following broadcasts are mandatory for all aircraft on a CTAF (R) and for all radio-equipped aircraft on other CTAFs. 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 national annual fly-in. Arrival and transit broadcastsAll aircraft reaching the vicinity of an aerodrome within Class G airspace must monitor the airfield frequency and make these broadcasts on that frequency:
Broadcasts within the circuit
Final approach broadcasts for straight in approaches
Departure broadcastsAll aircraft operating from a non-towered aerodrome must monitor the airfield CTAF and make the following broadcasts on that frequency:
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5.3 Prescribed CTAF broadcast formatsAll VFR broadcasts from an aircraft station in Class G are quite simple, having much the same content presented in much the same sequence:
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'. Transit call format
Inbound call format
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:
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 you could use the local time minutes and append the term 'LOCAL TIME' to the message; i.e. 'INBOUND ESTIMATE BOURKE ON THE HOUR LOCAL TIME'. Joining circuit call format
Turning downwind call formatThe 'turning downwind' call should be made when starting the turn onto the downwind leg — if the circuit was joined crosswind or if the aircraft is doing circuits and bumps (touch 'n goes).
Turning base call formatThe '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.
Turning final call formatThe 'turning final' call should be made when starting the turn onto final.
Finals report format for straight-in approachesThe '3 mile final and 1 mile final ' calls must be made at the corresponding distance from the runway threshold. The 3 mile and 1 mile final reports are roughly equivalent to the 'turning base' and 'turning final' reports.
Clear of runway call formatThis call that you have turned off the runway particularly helps a following aircraft on a straight-in approach or where a rise in the runway obscures the view of an aircraft preparing to take-off.
Taxiing call formatThe 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.
Entering runway call formatThe '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 or final legs to be prepared to go around in the event that there is a conflict.
Aircraft should remain at the runway holding point until all checks are complete and the runway and the approach are 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. Broadcast etiquetteThere are a few unwritten rules that greatly aid understanding by those maintaining a listening watch on the frequency:
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5.4 Discretionary broadcast formatsAlthough 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 mandatory calls.Going around call formatIf it is necessary to abort the landing and conduct a go-around, a broadcast may be helpful to others.
Airborne call formatAfter take-off and turning on course, an airborne report may be helpful to other aircraft if the departure is in a contra-circuit direction
Requesting informationThere 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:
5.5 Communicating with Unicom or CA/GRS stationsWhen 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'):
The informal response from the ground operator might be:
Before taxiing at an airfield with an Unicom or CA/GRS service an information request might take this form:
The response from the ground operator might be:
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5.6 CTAF response callsMaintaining 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 both courteous and good airmanship for recreational pilots to allow priority to RPT, 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.
5.7 En route proceduresClass G airspaceThere 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 para 60.1."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:
So what's the 'appropriate' frequency? This could be:
Class E airspaceAs 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. |
5.8 Acquiring weather and other information in-flightAirservices 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:
AERISAERIS is a network of 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. More information will be found in ERSA GEN-FIS-1. ATISATIS 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.AWISAustralian 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. For the access telephone numbers and the VHF frequencies look for 'location information' on BOM's Aerodrome Weather Information Service (AWIS) page; if a user name is requested use 'bomw0007' and the password 'aviation'. 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. FlightwatchFlightwatch 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 non-controlled 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:
 Acquiring QNHIt 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:
5.9 The Radar Information Service [RIS] Transponder-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 radar information service on the appropriate ATC frequency. The RIS 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 RIS, so that ATC monitor your flight progress and can also help you avoid Class C or D 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.
Position information and flight following request call format
5.10 Sourcing frequency informationThe 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.
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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 |
 The next section of the VHF radiocommunications guide outlines safety and emergency procedures |
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