5.4.1 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.

5.4.2 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.

5.4.3 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

For example:

• 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

For example:

• 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

For example:

• 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

For example:

• 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

For example:

• 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

For example:

• 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

For example:

• 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

For example:

• 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.

5.4.4 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

For example:

• 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

5.4.5 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.

5.4.6 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.

5.4.7 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.

5.4.8 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.

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

5.4.9 The Surveillance Information Service [SIS]

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 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.

5.4.10 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.

	PCA	ERC-L	VTC	VNC	ERSA
VHF coverage at 5000 feet
VHF coverage at 10000 feet
HF network sector frequencies
SIS frequencies
Flightwatch frequencies
FIA boundaries
FIS frequencies at airfields
Airfields where FIS contact possible from ground
Airfield Unicom frequencies
VOR/NDB frequencies and ID
CTAFs

STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

5.5.1 Communications when in difficulties

Assess the probable outcomes of the available alternative actions

When a non-instrument rated recreational pilot realises that he/she is likely to be in difficulties (very low on fuel, lost or in failing light, encountering low cloud and rising terrain) or is already in difficulty (the engine or a control circuit has failed), the top priorities are: (a) fly the aircraft, (b) continue flying the aircraft whilst running through the pre-planned emergency drills and (c) decide the best landing area. During this period an assessment must be made of the probable outcome in terms of possible injury and/or survival following the landing.

• If the aircraft is a low-momentum type, is normally controllable, pilot only onboard, visibility is okay and the area is clear terrain with a normal rural population density and road infrastructure, then the landing should not be life-threatening to a reasonably competent pilot. If unable to remedy the fault on the ground, the pilot won't have to walk far to find assistance. In this circumstance many recreational aircraft pilots, particularly those in single-seat taildraggers, would not consider communicating any form of alert except, perhaps, to advise an accompanying aircraft. This brings to mind the RA-Aus pilot who underwent three forced landings, due to engine stoppages, on one journey to NATFLY before he finally made it.
• On the other hand if the pilot is experiencing control difficulty, or the terrain is rough and/or heavily treed, or in a more remote area, or the type of aircraft is such that it is likely that the landing cannot be carried out without some risk of occupant injury then the pilot would be well advised to initiate a distress broadcast — a MAYDAY call — even if there is little time available.
  
  Distress is defined as a situation where — in the opinion of the pilot in command — an aircraft (or vessel, vehicle or person) is in grave and imminent danger and requires immediate assistance. The word 'Mayday', an anglicised version of the French 'm'aider' [help me], was adopted in 1927 as the standard radiotelephony distress call.

The VHF frequency chosen, at the pilot's discretion, depends on circumstances and should be that which is most likely to provide a quick response or rapid assistance at the scene. The first choice response station will usually be Brisbane or Melbourne Centre on the flight information area frequency or a terminal area frequency. If aircraft height is such that Air Traffic Services are not contactable and the frequency already tuned is a CTAF and other aircraft or a Unicom operator are known to be listening out then use that frequency (but bear in mind CTAFs are not monitored by Air Traffic Services). In very remote areas another option is the international VHF voice distress frequency of 121.5 MHz, which, though also not monitored by Air Traffic Services, is continually monitored by RPT aircraft and others with a good citizen attitude and the communications equipment capability to monitor more than one frequency; see Boyd Munro's comments.

But the pilot's primary task is to fly the aircraft while selecting the best landing site and minimising risk to all persons; it is not productive to stall the aircraft while attempting to change frequencies (or just to find an appropriate frequency) or communicate, and you certainly don't want to risk dropping a hand-held transceiver.

Requesting assistance

There are circumstances that make some form of alert or urgency communication advisable, even if the pilot doesn't want to ask for help or feels a bit embarrassed about it. (But — in my book — better red than dead.) The pilot who is encountering difficulties might decide to request assistance from the ATC on-request flight information service Flightwatch — if contactable on the flight information area frequency — advising the difficulty, the aircraft's approximate location and the pilot's intentions: without the pilot initiating an emergency status. The Flightwatch operator may arrange to directly assist or may decide to treat the situation as an emergency and declare the appropriate emergency phase — uncertainty, alert or distress. See AIP GEN 3.6.

The call format might be:

• FLIGHTWATCH*
• THRUSTER ZERO TWO EIGHT SIX
• EXPERIENCING NAVIGATION DIFFICULTIES IN DETERIORATING VISIBILITY
• REQUEST NAVIGATION ADVISORY

*Note: ERSA-GEN-FIS 3.2 indicates it is not necessary to prefix the generic 'Flightwatch' callsign with the callsign of the ATC unit e.g. 'Brisbane Centre'.

If the pilot considers there is some uncertainty and/or urgency in the situation, and that assistance may be needed, then he/she may decide to advise of an urgency condition and initiate a PAN-PAN broadcast — stating the nature of the alert, pilot's intentions and assistance desired. Pan derives from the French 'panne' meaning 'breakdown'.

Declaring an emergency in an appropriate situation displays good airmanship — and people do like to help. Read the article 'Salvation from above' in the January–February 2001 issue of the Australian Civil Aviation Safety Authority's Flight Safety Australia magazine. A categorised index of articles of interest to recreational pilots contained in Flight Safety Australia since 1998 is available on this site.

The VHF urgency and distress calls

PAN-PAN and MAYDAY calls are internationally recognised emergency transmissions that initiate ICAO prescribed procedures and offer decided advantages to the pilot in difficulties.

• Distress calls have absolute priority over all other communications on that frequency, and the word MAYDAY commands immediate radio silence. Radio silence should continue until listeners have determined that communication has been properly established between the station in distress and a responsible authority, and that assistance is being provided.
• Similarly PAN-PAN urgency communications have priority over all other communications except distress calls.
• The Flightwatch flight information service or the ATS alerting service will immediately acknowledge any distress or urgency message received, coordinate communications and alert the Australian Search and Rescue organisation [AusSAR] on receipt of a distress call.
• If any station monitoring a distress or urgency message becomes aware that Flightwatch either has not received the message or, having received it, cannot establish contact with the originator, that station has a responsibility to contact Flightwatch and/or the aircraft, and offer assistance — possibly as a relay station — which may entail remaining in the area.
• There is an understanding that "In an emergency requiring immediate action, the pilot in command may deviate from any rule ... to the extent required to meet the emergency." However, you would need to ensure that any such departure doesn't cause risk to someone else. Nothing in the CASRs acts to protect the pilot against civil liability in the case of damage to persons or property. Also declaration of an emergency while entering an active restricted area does not guarantee safe passage.
• For transponder-equipped aircraft also see transponder emergency procedure.

MAYDAY call format

To remove any uncertainty whether a monitored call is an emergency call, it is most advisable to precede the call with the recognised priorities PAN-PAN or MAYDAY, then transmit as much of the following detail as circumstances allow — bearing in mind the pilot's first priority is to fly the aircraft. If experiencing controllability problems or an engine failure when close to the surface, there won't be much time to bother about formal communication formats.

If time is available, distress calls have the preferred format:

1. Priority = MAYDAY (repeated three times)
2. Calling station ID (repeated three times, if time permits) and aircraft type
3. Nature of distress
4. Calling station position, heading and altitude
5. Intentions
6. Other useful information

For example, with an engine failure over rough, hilly terrain:

• MAYDAY MAYDAY MAYDAY
• THRUSTER ZERO TWO EIGHT SIX / ZERO TWO EIGHT SIX / ZERO TWO EIGHT SIX
• ENGINE FAILURE
• ESTIMATED POSITION THREE ZERO MILES SOUTH EAST ALBURY / HEADING EAST / NOW DESCENDING THROUGH THREE THOUSAND
• INTEND FORCED LANDING IN MITTA VALLEY
• TWO POB / THRUSTER ZERO TWO EIGHT SIX / MAYDAY

Note the last line includes the information that there are two persons on board [POB] and repeats the call sign and the MAYDAY priority. It might help an Air Traffic Services operator, managing several frequencies, if the frequency in use was also transmitted.

PAN-PAN call format

Urgency calls have the preferred format:

1. Priority = PAN-PAN (three times)
2. Called station ID
3. Calling station ID and aircraft type
4. Nature of emergency
5. Calling station estimated position, altitude and heading
6. Request or intentions

Utilising GPS

If the pilot in distress is able to communicate, or has established contact, a functioning GPS is a great advantage to everyone concerned, because the pilot is then able to provide a latitude and longitude position probably accurate to 100 metres. Consequently any search only entails a direct flight to that position by one aircraft. Some distress beacons also include Global Positioning System input capability.

Other communication means

UHF citizen's band [CB]. In rural and outback areas, particularly in the vicinity of the arterial roads, there is widespread usage of UHF CB radios by truck drivers, four-wheel drive vehicles, road crews, mustering crews and fencers. There are 40 CB channels located between 476.425 and 477.400 MHz in 0.025 MHz steps. The road vehicles listen out on channel 40, and channels 5 and 35 are emergency frequencies. Some VHF handheld transceivers might include UHF CB capability and there is quite a good UHF repeater system (channels 1–8/31–38) established in Australia.

A cellular mobile communication device may be useful in advising your situation to others. An individual's ability to make radio frequency transmissions in the Australian cellular mobile communications 850, 900, 1800 and 2100 MHz bands is legitimised by the Radiocommunications (Cellular Mobile Telecommunications Devices) Class Licence 2002.

An activated mobile communication device in a high-speed aircraft may cause channel interference across cells, but in July 2010 the Australian Communications and Media Authority [ACMA] amended the class licence (which previously prohibited the airborne use of mobile communication devices) to allow operation of a mobile communication device in an airborne aircraft above an altitude of 10 000 feet or, perhaps, 20 000 feet, but only to communicate with a licensed public mobile telecommunications base transceiver station (a 'pico cell' such as those used in large buildings) onboard the aircraft with connection to telecommunications satellites. A control unit blocks onboard devices from terrestrial signals. Under these conditions the mobile devices in the aircraft operate at very low power.

So, the class licence authorises persons to use mobile communication devices in aircraft if they are in an airliner equipped with a 'pico cell' unit (and operating under a public telecommunications service licence). The class licence does not authorise the use of any other form of mobile communication device in any airborne aircraft at any altitude. However, in an emergency safety has priority so airborne pilots might contact the ATC centres by mobile 'phone. The telephone numbers of the state ATC centres and the SAR hotline (1800 215 257) are given in ERSA GEN-FIS 'Use of mobile 'phones in aircraft' — store the numbers in your 'phone.

For recommended actions during and following an emergency please read all of the ERSA Emergency Procedures Section ERSA EMERG; particularly the 'Activation of ELT' and the survival sub-sections.

5.5.2 Distress beacons and AusSAR

ELTs, EPIRBs and PLBs

In a life-threatening situation the pilot may activate a radio distress beacon when approaching, or on, the surface. The signal from the beacon will be detected by the specialised search and rescue system — Sarsat (Search And Rescue Satellite Aided Tracking system) and the Russian Cospas. The satellite-mounted Cospas-Sarsat receivers monitor only the global distress frequency, 406.025 MHz and are reputed to have been involved in more than 7000 rescues since the system was introduced in 1982. Analogue transmissions might also be picked up by nearby aircraft — regular passenger transport aircraft usually continually monitor the 121.5 MHz frequency and military aircraft monitor 243.0 MHz.

In the Australian aviation regulatory environment, the generic name for distress beacons is Emergency Locator Transmitters [ELTs]. ELTs are usually a fixed installation within larger aircraft, but may be demountable. When armed, ELTs are designed to be activated automatically (perhaps by a g-switch) under a high-impact deceleration; or they can be manually activated by the pilot. (Unfortunately ELTs may not survive a high impact landing or the antenna may be disconnected in a lesser accident.)

Similarly, the generic name for 406.025 MHz maritime environment beacons is Emergency Position Indicating Radio Beacons [EPIRBs]. The significant difference between EPIRBs and ELTs is that the former are buoyant and work at their best when floating freely and upright, while the ELTs work best on land — though they should be waterproof. The most expensive EPIRB is the 'float free' or 'float-to-the-surface', automatically activated maritime only type. Smaller, lanyard-equipped, manually operated, category 2 EPIRBs are designed to be placed in the water and allowed to float upright.

Personal Locator Beacons [PLBs] were originally designed for personal use by ground travellers in a rugged environment or by those recreational sailors who don't venture very far out to sea — they probably float but perhaps not upright. The manually activated, pocket-sized, analogue PLBs were extensively used by recreational pilots — among many other users.

In the Australian aviation scene PLBs and manually activated EPIRBs are classified as portable ELTs so, for aviation regulatory purposes, the ELT term encompasses fixed-installation ELTs and portable ELTs; the latter being the digital PLBs and the manually activated digital EPIRBs. Recreational aviation pilots carry PLBs or, if undertaking significant water crossings, should carry the personal EPIRBs that can be attached to a lifejacket or to clothing.

(The term ELB [Electronic Locator Beacon] is sometimes used but this term is no longer defined in aviation regulations or by the Australian Maritime Safety Authority — which has search and rescue responsibility in the Australian region — so the term has no valid usage and adds to the confusion between aviation and AMSA definitions. ELBs were once in use as a 121.5 MHz beacon but their transmission format was not satellite-compatible and production ceased in the early '90s.)

The now superseded analogue versions of PLBs/personal EPIRBs transmitted on the 121.5 MHz voice frequency and simultaneously on 243.0 MHz, but not 406.025 MHz. For aural recognition and homing that continuous wave transmission is modulated with a swept tone sounding like a two-tone siren and audible via a VHF transceiver. The 121.5 or 243.0 MHz transmission is used as a short range homing signal by search aircraft or surface vehicles. On 1 February 2010 the class licence for the 121.5/243.0 MHz distress beacons was finally withdrawn by the Australian Communications and Media Authority [ACMA], consequently it is now illegal to use those beacons for any purpose.

On land there might be a requirement that PLBs/EPIRBs, when activated, must be placed in the centre of a ground mat formed from a sheet of aluminium kitchen foil, about 120 cm square — which provides the 56 cm radius ground plane. Read 'Activation of ELT' within the emergency procedures section of ERSA.

Remember the requirement (AIP GEN 3.6 para 8.2) that pilots should monitor 121.5 MHz before engine-start and after engine-shutdown, to check for the 'two-tone siren' distress transmissions — and to ensure that your own beacon is not activated inadvertently.

Distress beacons have been used in Australian aviation for at least 45 years and are an essential item for pilots who fly in sparsely populated areas, and for vehicle drivers who operate in remote areas. The buyer of a distress beacon should be well aware of how to keep it secure and to use it correctly, effectively, and only when in a life-threatening situation; also how to finally dispose of it without possibly causing costly problems to AusSAR. For beacon disposal instructions see beacons.amsa.gov.au/batteries-disposal.html.

The 406.025 MHz ELTs

On 1 February 2009, the Cospas-Sarsat satellites ceased processing distress signals on 121.5 MHz and now only process signals from the 406.025 MHz digitally-encoded PLBs, ELTs or EPIRBs. So, search (and rescue) for persons using the 121.5 MHz only units is totally dependent on time-consuming, expensive and difficult — and possibly dangerous — air and ground searches.

The digitally-encoded PLBs, ELTs and EPIRBs that operate on 406.025 MHz, quickly provide position accuracy to within 5 kilometres or so using satellite trilateration. If the beacon has an integrated GPS input the location coordinate data are transmitted to the satellite, pinpointing the site to within 100 metres or less. This makes redundant the search portion of the rescue operation and greatly aids rapid recovery; and rapid recovery is vital when the aircraft occupants are injured or in difficult circumstances. The 406.025 MHz beacons generally also transmit a low power analogue 121.5 MHz final stage aircraft homing signal; for example, the Australian MT410G PLB at left.

When activated the 406.025 MHz beacons send a 0.4-second data packet every 50 seconds. The packet includes a 15 hexadecimal character beacon identity code plus the country/SAR authority code within a 30 hexadecimal character distress message. That message is retransmitted by the satellite to the two AMSA ground stations. The hexadecimal identity code, marked on the unit as purchased, must be known to AusSAR's database, and linked to your personal and aircraft details. Part of the functional working of the 406.025 MHz beacon search and rescue system is having the owner of the beacon register it with the Australian Maritime Safety Authority [AMSA].

Requirement to register and carry 406.025 MHz beacons

The requirement for an Australian aircraft to carry an approved distress beacon or emergency locator transmitter is stated in CAR 252A (as amended 1 February 2009). Every two-place recreational aircraft operating beyond 50 nm from their departure point is required to carry a 406 MHz beacon registered with AMSA. Single-place aircraft are amongst those exempted in CAR252A, so carriage of a beacon is not mandatory for CAO 95.10 aircraft — but it is certainly wise to do so.

So, recreational pilots should acquire a 406 MHz beacon with internal GPS input (for example, the MT410G costs about $650) and register that beacon. In order to make the process of registration and upkeep of details easier, AMSA have an online registration program. This system is available to all beacon owners to use and there is no charge for its use; go to beacons.amsa.gov.au to register your unit and to find more details regarding how to purchase PLBs. AMSA will provide a registration sticker to be placed on the unit, the stickers provide owners and Flight Operations Inspectors with proof of current registration.

The ELT registration must be renewed every two years and a new sticker attached to the device; see 'Renewing your registration'.

Note: if a beacon has been activated inadvertently, switch it off and notify the Rescue Coordination Centre Australia by calling 1800 641 792 to ensure a search and rescue operation is not commenced. There is no penalty for inadvertent activations.

According to their website — 'since its inception in 1982 the Cospas-Sarsat System has provided distress alert information which has assisted in the rescue of 26,779 persons in 7,268 distress situations [land, sea and air]. In 2008 only, the System provided information which was used to rescue 1,981 persons in 502 distress situations. The locations of these events are depicted on the map below.'

For further general information, the next page in this guide is a document Aviation Distress Beacons written some time ago by David McBrien of AusSAR.

Personal flight tracking systems

There are several flight tracking systems available which allow interested parties to follow the progress of a flight via the internet. For example, Spidertracks is a system developed in New Zealand that uses a small (12×6×3 cm) demountable transceiver in the aircraft (with its own GPS engine) to send location, heading, speed, altitude reports at nominated time intervals — via the Iridium satellite global communications network — to a host computer, which users can access via the internet. The display includes flight track, reporting times and locations overlaid on a Google Earth map. There is a facility available which will activate email or text notification — to a user-nominated person or group of persons — if three contiguous reports are missed. Cost may be a problem.

Australian Search and Rescue (AusSAR)

If a registered civil aircraft issues a MAYDAY call, or is seen to crash away from a controlled aerodrome or is reported missing, Australian Search and Rescue has national responsibility for coordinating the search and rescue. In addition, AusSAR monitors satellite-intercepted signals via two ground stations in Australia and one in New Zealand. AusSAR is responsible for delivering search and rescue coordination in response to an activated distress beacon within AusSAR's area of responsibility — which covers all the Earth's surface between 75° East and 163° East and roughly 10° South to 90° South.

Further information is contained in the document Understanding SAR services.

5.5.3 Aircraft radar beacon transponders

Mode A/C transponders

Transponders are specialised radio devices that form the airborne part of the Air Traffic Control Radar Beacon System [ATCRBS "at-crabs"].

Transponders respond to a 1030 MHz interrogation pulse, from an air traffic control secondary surveillance radar [SSR], by returning a high-energy 1090 MHz pulse that strengthens the radar return signal. Lower power primary surveillance radar [PSR] exists only within about 50 nm of the major civilian and military airports but such radars don't interrogate airborne transponders. SSR range is at least 100 nm from the radar unit, depending on target height. The surveillance (i.e. computer-aided search and track) radars provide only bearing and distance from the radar site, target height is provided by the airborne transponder.

In addition, the response from transponders fitted to smaller civilian aircraft normally consists of a 12-bit ATC assigned identity/status code plus a 12-bit altitude reading (in units of 100 feet) which appear on the controller's SSR screen with the aircraft 'paint'. Civilian units with this identity (Mode A) plus altitude encoding (Mode C) interrogation response capability are known as Mode A/C transponders, sometimes they are referred to as 'Mode 3A/C'; the '3' just refers to a US military classification. The transponders receive the Mode C altitude data from altitude encoding devices.

The 12-bit Mode A identity code is separated into four three-bit numerals using octal rather than decimal notation. Thus each numeral will be in the range 0–7; i.e. the numerals 8 and 9 will not appear in any identity/status code. The standard four-digit non-discrete identity code 'squawked*' by VFR aircraft is '1200' (all non-discrete codes end in '00') until radio contact with Air Traffic Services, who might then instruct the pilot to squawk a particular discrete (i.e. individual) code; e.g. 4367. The maximum number of discrete identity codes available for assignment at any one time is about 4000 (in decimal notation).

*(Note: the 'squawk' term originated in Britain early in the second World War when the Chain Home early warning radar network was used for the first ground controlled fighter interception system against incoming air raids. The RAF fighters were equipped with a rudimentary 'identification friend or foe' (IFF) transponder, code-named 'Parrot'. When the ground controller required a flight or squadron to switch on their transponders the instruction was "Squawk your parrot". Conversely, "Strangle your parrot" to switch off.)

Mode A/C transponders have a very important 'identify' [IDENT] or 'special position identification' [SPI] facility which, when operated, momentarily adds an additional bit to the '1200' non-discrete identity code, or whatever discrete code is being used by the pilot. That causes the aircraft's 'paint' to brighten or change colour on the controller's display. So, for example, when the controller wishes to locate a particular aircraft on the display screen, among all those currently squawking '1200', the controller will request the pilot to "squawk ident"; i.e. operate the 'ident' button, knob or spring-loaded toggle switch. Pilots must not squawk 'IDENT' unless told to do so by ATC or when first squawking an emergency code.

The non-discrete transponder squawk codes (for emergency use only) are:

• 7700 emergency
• 7600 VHF communications failure
• 7500 unlawful interference (i.e. hijacking).

See transponder emergency procedure below.

Mode S transponders

The Mode A/C radar surveillance system is rather limited. The Mode S transponders, carried by regular passenger transport aircraft, use their National Airworthiness Authority [CASA for Australian aircraft] assigned permanent 'ICAO 24-bit Aircraft Address'. The 24 binary digits allow a total of 16.8 million individual addresses; thus every aircraft can be permanently assigned a unique address, generally based on the aircraft's country of registration and issued by their National Airworthiness Authority. Consequently, those aircraft can be selectively addressed by ground stations or other aircraft for transfer of information as digital data. This message format is called Mode S (for 'selective address') but the transponders also have the normal Mode A/C functions.

*Note: Binary, octal, decimal and hexadecimal numerical notation. Our everyday decimal numbering system has a base of ten with 10 markers 0–9. Octal and hexadecimal notation refer to versions of computer numerical display that assist human perception of the binary digit representation used in computers. Binary numbering is base-2 with two states (on or off) per binary digit (bit) representing 0 and 1. Octal notation is base-8 with eight markers 0–7 and uses one group of three bits to represent any of the eight numerals 0–7. The hexadecimal (or hex) numbering system is base-16 with 16 markers 0–9 plus A–F, the latter representing the decimal numerics 10 through 15. A decimal number of '255' is represented by the hex number 'FF'. Hexadecimal uses one group of four bits to represent any of the sixteen numerals 0–15 rather than the 8-bit byte normally used for alphanumeric coding.

For Australian aircraft the ICAO 24-bit Aircraft Address code, also known as the 'Mode S Transponder Code is usually stated in 6-digit hexadecimal notation format. All Australian civil aircraft with a Mode S transponder installed are required to have a registered permanent ICAO 24-bit Aircraft Address assigned; this is accomplished by emailing CASA at aircraft.register@casa.gov.au who will assign a permanent ICAO 24-bit Aircraft Address code for that aircraft in the range '7C0000' to '7F0000'. For RA-Aus registered aircraft the code may be entered into a Mode S transponder by the aircraft owner; for aircraft with national registration (i.e. VH) the code must be entered into a Mode S transponder by an appropriately trained and rated licensed aircraft maintenance engineer (LAME), or CASA authorised person, at the time of transponder installation and re-tested at 2-year intervals.

Note: only the CASA assigned aircraft address should be entered into the 24-bit hexadecimal field otherwise there is the possibility of duplication of aircraft addresses. If a CASA-assigned aircraft address has not been entered and verified in a Mode S transponder then the unit may only be operated in A/C mode.

Also, as with the Mode A/C transponders, the Mode S transponders have an identification function that may be known as 'Aircraft Identification', 'Flight Identification' or 'FLIGHTID'. This Aircraft Identification may be no more than seven alphanumeric characters but, for RA-Aus registered aircraft, CASA require the Aircraft Identification to be five alphanumeric characters consisting of the four numeric digits of the aircraft's registration mark preceded by the letter 'R' (for RA-Aus) without hyphens or included spaces, e.g. Jabiru 24-7147's identification is 'R7147'. For RA-Aus aircraft the Aircraft Identification is a permanent code, for other aircraft it may be entered/changed by the pilot as required.

In Australia, prior to 2010, there was no Mode S secondary surveillance radar network so the main Mode S transponder function was to allow aircraft equipped with Traffic Alert and Collision Avoidance Systems [TCAS] to communicate directly with each other, thereby enabling mutual resolution of potential traffic conflicts. The transponders – in combination with a GNSS receiver – periodically 'squitter' a burst of data containing tracking information such as the aircraft's position, altitude, vector and velocity. (Squitter means a rapid R/F emission.) Such transponders also act as the aircraft's digital modem terminal for data upload/download and distribution.

Mode S can also provide faster, more accurate ATC surveillance, provided the ground SSRs are of the fast, single-pulse interrogation Mode S type. The non-Mode S Australian SSRs are now in the process of replacement, both in the main city hubs and en route.

When interrogated by a Mode S SSR a Mode S transponder replies with its Flight Identification plus its ICAO Aircraft Address, plus other relevant data.

From February 2014 an aircraft that is newly registered (or that is modified by having its transponder installation replaced) and that is operated in Class A, B, C or E airspace, or above 10 000 feet amsl in Class G airspace, must carry a serviceable Mode S transponder, but that Mode S transponder is not required to have the 'extended squitter' hardware and software (known as '1090ES') to transmit Automatic Dependent Surveillance–Broadcast [ADS-B] data. The term 'extended squitter' refers to an additional [112-bit] ADS-B data packet, which is part of the enhanced Mode S transponder data link standards for ADS-B. The 1090ES satellite-based surveillance and traffic management system is currently implemented for Australian airspace above 29 000 feet. See the Australian ADS-B implementation program.

TCAS

The Traffic Alert and Collision Avoidance Systems [TCAS II], fitted to all Australian RPT aircraft exceeding 30-passenger capability, also send out Mode C interrogation pulses in the same manner as an SSR, and use the interrogation responses broadcast from aircraft Mode A/C transponders (within a range of 14 nm) to determine collision risk. (TCAS computers determine the velocity vector of an aircraft within range — ascertaining distance by the response time, bearing by a directional antenna and altitude from the 12-bit reading encoded in the response.) If there is no altitude given then the computer can only provide a traffic alert rather than a 'resolution advisory' recommending a particular action to the pilot. TCAS II won't detect an aircraft fitted with an operating Mode A-only transponder.

TCAS systems also utilise their Mode S-capable transponders to transfer data between aircraft TCAS systems for mutual resolution of traffic conflicts, or to provide a data upload/download link with a ground station. For a description of TCAS read the article 'Collision Avoidance' in the April 1999 issue of the Australian Civil Aviation Safety Authority's Flight Safety Australia magazine.

Transponder operating regulations

For traffic separation purposes all aircraft — including recreational aircraft — operating in Class A, C and E Australian airspace, or in any airspace above 10 000 feet, must be fitted with an operating Mode A/C transponder. If an aircraft is transponder-equipped the unit must be operated constantly, whether in controlled or non-controlled airspace. There are some exemptions in Class E if the aircraft's electrical system is not capable of continuously powering a transponder. No aircraft may operate in Class E within 40 nm of a Class D tower without a functioning transponder. For further information see controlled airspace. A recreational aircraft operating in Class E should check with Air Traffic Control to confirm that the transponder is functioning correctly.

Normal operating procedure:

1. After engine-start turn the transponder mode switch from 'OFF' to 'STBY' (standby) to warm up the unit — which may take a couple of minutes. When the transponder is in 'STBY' it will not respond to an SSR interrogation. Set the identity code '1200' unless advised otherwise by ATC.

2. Before take-off turn the mode switch to 'ALT' (altitude) rather than the 'ON' position. Unless ATC instructs you to do so there is really no need ever to use the 'ON' position. The 'ON' position directs the transponder to respond only to a Mode A interrogation. When 'ALT' is selected, even if there is no altitude encoder fitted, the transponder will still return a response pulse to a Mode C interrogation coming from a ground radar or from a TCAS aircraft, but without any altitude data of course. Leave the switch in the 'ALT' position until turning off the runway at the destination, unless the identity code is to be changed during flight; in which case place the unit in 'STBY' mode while the change is being effected.

3. For further information on operation of transponders see AIP ENR 1.6 subsection 7.

A user's manual for the Australian Microair T2000 transponder may be downloaded from the Microair website.

Transponder emergency procedure

For any transponder-equipped aircraft within radar coverage — say, up to 100 nm from the SSR site for lower altitudes — and whether outside (or underneath) controlled airspace, the ATC radar emergency service will provide navigation assistance if the aircraft is in distress or experiencing navigational difficulties.

In an emergency situation the pilot should select the emergency status code 7700, operate the 'IDENT' function and, if possible, contact the service on the overlying en-route area control frequency shown on the ERC-L, call-sign CENTRE; e.g. BRISBANE CENTRE.

• PAN-PAN PAN-PAN PAN-PAN
• BRISBANE CENTRE
• THRUSTER ZERO TWO EIGHT SIX / ZERO TWO EIGHT SIX / ZERO TWO EIGHT SIX
• EXPERIENCING NAVIGATION DIFFICULTIES IN DETERIORATING VISIBILITY
• REQUEST POSITION [or NAVIGATION] ADVISORY
• SQUAWKING 7700

Deviation into an active restricted zone

Should an aircraft be forced to deviate into an active restricted zone due to the weather — without an ATC clearance — then the pilot must declare a PAN-PAN, squawk 7700 and broadcast on 121.5 MHz and on the appropriate ATC frequency. ATC will declare an 'Alert Phase'.

The declaration of an emergency will not guarantee safe passage in a hazardous restricted zone.

Mode C transponder maintenance

RA-Aus aircraft owners should note that transponders with an active altitude reporting facility (altitude encoding altimeter or a blind encoder) must be maintained in accordance with CASA regulations not RA-Aus regulations. CAO 100.5 appendix 1 requires that the system is tested by a CASA-licensed maintenance engineer at intervals not exceeding 24 months or after any change/modification to the altitude reporting system component(s) or interwiring. Code 2100 is used by maintenance personnel for testing purposes.

5.5.4 Can it ever be appropriate to monitor 121.5 MHz en route?

The following was written by Boyd Munro of Air Safety Australia

121.5 is the International Distress Frequency. A recent survey by Air Safety Australia has revealed that few Australian pilots monitor 121.5, apart from those who work or have worked for an airline, and those with significant overseas experience. I got a big surprise from this, because I always monitor 121.5 en route without even stopping to think why. It’s just something I do, like getting dressed before I leave the house in the morning.

Remember that “monitor” in this context means “listen without talking”. The survey also showed that the term “monitor” is quite widely misunderstood.

For the most part we Australian pilots are not trained to monitor 121.5 when flying en route, but there are powerful reasons why we should.

1. We are instantly available to another pilot who experiences an emergency in the air, or crashes but still has a working radio and calls on the International Distress Frequency. This is not merely good airmanship, it is responsible citizenship.

2. We can pick up ELT signals, so if another pilot crashes we can bring help to him. ELT signals are also picked up by satellites [this capability ceased 1 February 2009 ... JB] but hours can elapse before one of those satellites passes over the accident site, and if the ELT’s antenna was damaged in the crash the high-flying satellite may not be able to pick up the signal at all. Airmanship/citizenship again.

3. We can be contacted at any time. For example “Aircraft at position X, you are entering restricted area R123 and will be intercepted unless you make a 180 turn and leave the area forthwith.”

4. All airlines monitor 121.5 en route.

5. ICAO requires that all aircraft monitor 121.5 at all times in areas where ELTs must be carried (which includes the whole of Australia).

6. ICAO recommends that all aircraft monitor 121.5 at all times to the extent possible.

7. If you crash and survive but are injured, 121.5 is, overall, the best frequency to use to summon assistance. A call on 121.5 is almost always answered anywhere in the world except in the polar regions. That’s because of the large number of good airmen and good citizens who monitor 121.5 when flying en route.

8. An intercepting aircraft is required by ICAO Annex 2 to call us on 121.5 before shooting us down.

Until 27th November 2003, the Australian recommendation (it was never a requirement) was that we should monitor the “Area Frequency” whilst en route VFR. The Australian recommendation now is that we monitor an appropriate frequency.

One practical benefit of monitoring 121.5 as opposed to the old “Area Frequency” is that 121.5 is almost silent. The only transmissions ever heard on 121.5 are those relating to distress or an aircraft which ATC has “lost” or transmissions made unintentionally (when the pilot intended to transmit on a different frequency). There is not the noise and distraction that occurs on an area frequency, leaving the pilot better able to fly the aircraft and maintain a good lookout.

Air Safety Australia urges all members to become familiar with monitoring 121.5 when flying en route, and then to always consider 121.5 when choosing which frequency to monitor when flying en route.

When you monitor 121.5 for the first time, remember that it is a silent frequency. Don’t make any transmissions on it unless you experience an emergency or you are responding to another aircraft which is experiencing an emergency and has transmitted on 121.5

Boyd Munro, 19th March 2004

STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

Distress beacons have been used in aviation for many years and, with some flights now being conducted without the lodgement of flight plans or flight notes or reporting progress, there is increasing importance on having an effective distress beacon as a means of last resort to alert the SAR system that you are in grave and imminent danger. The carriage of aviation distress beacons has been the subject of much debate in the past and this article is designed to bring readers up to date on some of the related issues.

The Cospas-Sarsat System

The Cospas-Sarsat satellite based system provides distress alerting and location information to search and rescue (SAR) authorities in the aviation, maritime and land environments. The system, which has been in operation since 1982, was originally designed to service a discrete distress frequency on 406.025 (generically stated as 406) MHz but the requirement was expanded to include a service on the aviation distress frequency of 121.5 MHz. In the case of the latter, the physical characteristics of the radio frequency and the output signal mean that there is coarser resolution with beacons operating on this frequency compared to those operating on the higher frequency. There has been major penetration of the 121.5 MHz beacons into non-aviation environments because of their relatively low cost.

The Cospas-Sarsat space component comprises a minimum of four Low Earth Orbit SAR (LEOSAR) satellites in polar orbit (two Russian Cospas satellites and two US SARSAT satellites with some reserve units) which monitor 121.5 and 406 MHz. Additionally, the Sarsat satellites monitor 243 MHz which is the military aviation distress frequency. More recently, a number of 406 MHz repeaters have been added to satellites in an equatorial geostationary orbit (termed 'GEOSAR') which provide a supplementary source for near instantaneous alerting of a distress alerting signal should the LEOSAR satellites not have the source in view. A more detailed explanation of the Cospas-Sarsat System can be obtained from the Cospas-Sarsat website.

Australia, through Australian Search and Rescue (AusSAR), is responsible for operating the nodal Cospas-Sarsat ground segment in the South West Pacific region. This is done by monitoring satellite intercepted signals from three ground stations, termed Local User Terminals (LUTs), in Albany, Bundaberg, and Wellington (NZ). With 121.5 MHz signals, the three elements in the process (ie the beacon, the satellite and the ground station) must be in view of each other. This is often termed 'local' coverage. With the 406 MHz signal, the satellite has the capacity to time tag the digital information and repeat it when it is next interrogated by a LUT. Through this means, 406 MHz beacons provide 'global' coverage.

Beacon Terminology

There have been a number of conventions used in the past to describe the various types of distress beacons that have been available in the market place. The current [1999] practice is to use Emergency Locator Transmitter (ELT) to describe those that are fitted to an aircraft, Emergency Position Indicating Radio Beacon (EPIRB) to describe those that are designed to float when immersed in water, and Personal Locator Beacon (PLB) to describe the portable units that are designed for personal use.

Compatibility of Older Technology Beacons

The 1960s saw the emergence of aviation distress beacons that operated on 121.5 MHz. These beacons met the FAA TSO C91 standard and provided an audible tone on the frequency with the likelihood that other aircraft or air traffic services in the area would intercept it and become aware that an aircraft was in distress. A large number of aircraft were fitted with crash activated fixed ELTs during this period and many commercial operators carried the man-portable Electronic Locator Beacons such as the Garret Rescue 99. These systems are not covered by the Cospas-Sarsat system and continue to rely on the aviation sector for SAR alerting purposes.

When a decision was taken to extend the Cospas-Sarsat system to include 121.5 MHz, the standard pertaining to aviation beacons was revisited and a new standard (FAA TSO C91A) was set making the beacon emission suitable for intercept by satellite. The new standard was not made retrospective and many aircraft in Australia still have non-Cospas-Sarsat compatible units fitted.

Benefits of Later Technology Beacons

The 121.5 MHz beacons in current production are relatively lightweight and inexpensive (with lower end of the market PLBs costing in the vicinity of $A200). They provide an affordable alternative to the more expensive 406 MHz beacons, (which currently [1999] cost from $A1600 but expected to get cheaper) but at an operational cost. There are also 406 MHz beacons being released on the market that have an embedded GPS and automatically report the beacon position in digital form via the satellite system when activated.

A comparison of the 121.5 MHz versus 406 MHz beacon technologies is shown below:

As a result of the location of the three LUTs servicing the Australian region, there are approximately fifty satellite passes serviced per day by AusSAR which results in a typical coverage area and average times for detection of a 121.5 MHz beacon.

It should be noted that there are areas, mainly in open ocean areas, around the world where there are gaps in 121.5 MHz coverage. Specific areas not covered of interest to Australia include the Antarctic area, the western Indian Ocean, the southern two thirds of Africa, the mid-southern Pacific Ocean and a gap on the regular Australia to United States air route between the Wellington and Hawaii ground sites. The gap in the southern two thirds of Africa is being addressed in two ways. The first is through ICAO which has mandated that international carriers are to be equipped with 406 MHz beacons when operating in Africa and the second is the planned location of a new LUT site in South Africa which is expected to be operational by late 1999.

The major implications for general aviation aircraft operating in Australia using 121.5 MHz beacons is that if the beacon is of the older type, then there is a reliance on other aircraft to detect the 121.5 MHz signal and raise the alarm. This may be problematic in many parts of Australia as only the larger commercial aircraft regularly monitor this frequency. If the beacon is Cospas-Sarsat compatible, the system will generally detect the signal but produce an ambiguous fix position either side of the satellite pass. Follow-on passes, collateral information, or the use of aircraft to investigate both possible positions are used to refine the correct distress beacon position.

This evolution takes time and the accuracy of the Cospas-Sarsat derived position is less accurate than with the more technically advanced 406 MHz beacon which usually provides an accurate position on the first pass. These beacons are also encoded with the details of the registered owner and, through the GEOSAR supplementary repeaters, provide near instantaneous advice that an emergency situation exists prior to a Cospas-Sarsat satellite pass. If an embedded GPS is fitted, a position will be passed along with this initial alert advice. The time critical nature of an adequate response is a major consideration when considering the safety of life.

Recent ICAO Decisions

The ICAO Council agreed in March 1999 that new aircraft operated on extended flights over water or flights over designated land areas shall be equipped with a 406 MHz beacon from 1 January 2002 and existing aircraft will be required to carry them from 1 January 2005. The Council also agreed to write to the Cospas-Sarsat governing body recommending that satellite processing of 121.5 MHz signals cease from 1 January 2009. [This came into effect February 2009] There is an expectation that the international maritime community will follow this lead.

A decision regarding the carriage of distress beacons by domestic aircraft in Australia rests with CASA. The FAA has announced that, at this stage, it plans not to mandate the carriage of 406 MHz beacons for general aviation aircraft. One of the major reasons for this position is that emerging technologies may have the potential to offer better and more cost effective solutions for this sector of the industry. There has also been some discussion that, given the dense aviation environment experienced in the US, that 121.5 MHz beacons may remain an effective option without the need for satellite monitoring given that all large commercial operators guard this frequency.

However, this is not the case in Australia where many remote operations are conducted without SAR details being lodged and where there is a reliance on distress beacons to act as the primary SAR alerting method. For remote area operations, the low frequency of other traffic in the area must be a consideration in the Australian context when selecting a replacement distress beacon.

Conclusion

Understanding the division of responsibilities between agencies, informing the system when you are in difficulties and understanding the limitations of distress beacon technology are all important aspects of airmanship. The professional response by the aviation community to the numerous SAR incidents that occur around Australia is publicly acknowledged for, without your assistance, the coordination role of AusSAR would be impossible.

STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

5.7.1 Aviation Search and Rescue [SAR]

Formation of AusSAR

A Ministerial decision was taken in early 1997 to amalgamate the two aviation and the one maritime Rescue Coordination Centres in Australia into a single agency. The report that the Minister acted upon offered a number of reasons for this approach including the fact that modern communications provided the capacity to coordinate aviation and maritime incidents from a single point bringing with it an improved national response capability. A factor influencing this decision was the increasing use of 121.5 MHz distress beacons where the environment of the unit or person in distress was unknown.

As a result, the Australian Maritime Safety Authority was given the responsibility and set up Australian Search and Rescue (AusSAR) as one of its divisions. AusSAR assumed the responsibility for aviation and maritime SAR on 1 July 1997 and maintains the national Rescue Coordination Centre (RCC) in Canberra. The Federal Government, as part of its community service obligations, meets the majority of its operating costs.

Aviation SAR

In general terms, AusSAR coordinates the response to aviation SAR incidents across Australia except where the incident is covered by other specific arrangements such as an Airport Emergency Plan. AusSAR is reliant on a number of external organisations, the distress frequency monitoring satellite system (Cospas-Sarsat) and the public to provide the SAR alerting function.

For aircraft, Airservices Australia is the major SAR alerting agency and its staff notify AusSAR when an aircraft is overdue after communications checks on Air Traffic Service (ATS) frequencies fail to make contact. Airservices Australia also notify AusSAR when there is information concerning imminent or known aircraft crashes, missing aircraft, or distress beacon activations detected by aircraft or ATS.

Relationship with Airservices Australia

There has been some confusion within the aviation community between the roles of AusSAR and Airservices Australia in regard to the SAR function. Airservices Australia provides In-flight Emergency Response and SAR alerting while AusSAR is responsible for SAR response. In-flight Emergency Response includes air traffic staff providing reasonable advice to assist the pilot in-flight to (1) operate in safe airspace; (2) resume normal operations; and (3) land the aircraft safely. SAR alerting by Airservices Australia (or a flight note holder) occurs when a problem is reported with an airborne aircraft, when no contact can be established following a missed report (arrival, departure, position, operations normal, lost contact following frequency change, etc) or at the expiration of a nominated SARTIME.

SARWATCH is a generic term covering SAR alerting based on either full-position procedures, scheduled reporting times, or SARTIME. Full-position procedures and scheduled reporting times are only applicable to IFR flights in all airspace classes and most monitored VFR flights operating in controlled airspace.

SARTIME is a time nominated by a pilot for the initiation of a SAR action if a report has not been received from the pilot by the nominated Airservices Australia unit.

A VFR pilot operating in Class G airspace may nominate a SARTIME to ATS but the progress of the flight is not monitored, though SAR action will be initiated if there is no communication from the pilot cancelling the SARTIME. Rather than nominating a SARTIME with ATS a flight note lodged with a responsible person, who will raise the alarm should the pilot not report in as scheduled, is preferred for VFR Class G operations.

5.7.2 The SARTIME database

As part of its responsibilities, Airservices Australia has introduced a centralised SARTIME database (CENSAR) where SARTIMEs are managed for aircraft arriving at or departing from all aerodromes or where a SARTIME has been submitted through a flight plan or by radio communication. CENSAR alerts the operator when a SARTIME has expired, at which time communications checks are commenced. If this process produces no results at the end of 15 minutes then the situation is passed to AusSAR as an Uncertainty Phase (INCERFA).

From an Airservices Australia perspective, a SARTIME can only be cancelled or varied at the request of the pilot. Incidental information that the aircraft has arrived safely at its destination cannot be used to cancel a SARTIME. However, this information is passed to AusSAR by the Airservices Australia CENSAR operator along with the declaration of the phase. AusSAR then takes whatever action is required to ensure the aircraft has arrived safely. Although not a required field in the flight plan, a destination telephone number (which may be a mobile phone number) can often bring a declared emergency phase to a quick conclusion.

A SARTIME held by CENSAR is cancelled by the pilot via radio to FLIGHTWATCH before changing to the CTAF or (the preferred method) after landing, via a telephone call to CENSAR (1800 814 931), see AIP ENR 1.1 paragraph 67. (Given the similarity between the names CENSAR and AusSAR, it is not surprising that AusSAR is frequently contacted by pilots wishing to amend or cancel their SARTIME.)

Other SAR Alerting and Intelligence Sources

Other major SAR alerting sources for AusSAR are the public, police, concerned relatives and friends, and people holding flight notes. The effectiveness of the SAR response is directly related to the timeliness, quality, and accuracy of the information that can be provided on missing aircraft to AusSAR. When other people agree to hold SARWATCH on behalf of a pilot, they should be aware of their responsibilities in the event of an incident and be made aware of the AusSAR aviation contact number (1800 815 257). The importance of early advice so that a search can be mounted before last light should not be missed.

While the flight note format at AIP ENR 1.10-23 is a good starting point for the type of information required, accurate intelligence is essential for the early location of an aircraft in distress. A detailed description of the aircraft, its occupants, its planned route, a list of safety equipment carried, whether an ELT and/or Personal Locator Beacon were being carried, whether the pilot and/or passengers usually carry a mobile phone, and so on are all valuable details to assist search planners. Personnel at the departure point such as refuellers and/or other aviators are often valuable sources of intelligence in this regard. Obviously, the most difficult SAR event is one where there is no SARTIME and no details.

5.7.3 AusSAR Aviation Activity Levels

During the previous month [March 1999] AusSAR conducted two major searches for missing aircraft. The first was a missing Bell 47 with two POB that was overdue on a flight from Coober Pedy to Kulgera. Following a wide search, the crash site was located on the third day but, unfortunately, there were no survivors. Twenty fixed wing and six rotary wing aircraft were involved at one stage during the search.

The second major search incident in March started with a concerned wife phoning AusSAR mid-afternoon saying that she had not heard from her husband. Except for crew details, the only information that she could provide was that it was a Jabiru with two POB expected to fly from Casino to Wangaratta that day. Following a rapid intelligence collection process, it was established that the aircraft had departed Casino at 1035 (local time) intending to track via Tenterfield, Moree and Narromine. Three aircraft conducted an initial search along the planned track before dark and a wide area search commenced the following day. Early into the wide area search a helicopter located the crash scene around 0800 (local) in rugged terrain 15 NM east of Tenterfield. Again, there were no survivors. On the second day, thirty fixed wing and fourteen rotary wing aircraft were involved in the search.

In addition to major searches, AusSAR was involved in numerous other activities relating to the aviation environment including a double fatality mid-air between a tug and a glider in the Waikerie area, the forced landing of an aircraft at Bungendore and responding to the ditching of a helicopter in the Cairns area with six of the seven people recovered safely. The aviation section of the statistical summary for the month of March shows that there were 741 aviation SAR phases acted upon and 37 incidents (which includes maritime incidents) where aviation assets were tasked. The aviation SAR phases included 128 IFR fail to report and 515 VFR fail to cancel SARTIME. However, the vast majority of the fail to report or fail to cancel SARTIME were 'technical' phases as the aircraft was safe but the appropriate procedures had not been followed to cancel it from the Airservices Australia system.

There is obviously a need for education in this area. Although these 'technical' phases are generally resolved quickly, they do impose a heavy workload and displace other staff efforts in improving the SAR system. The real difficulties are when a major SAR action is in progress and staff resources are being stretched to the limit. On these occasions, the number of 'technical' incidents can detract from marshalling the resources required to assist other aviators whom are believed to be in grave and imminent danger.

5.7.4 Informing the SAR System

The Requirement

It is fashionable to ponder on what the next decades will bring us. In the aviation sector ICAO has been very active in planning the introduction of technological systems that will enhance air traffic management especially on international routes. These types of systems will add a high degree of accuracy to the current aircraft position in the case of emergency and may take the search out of search and rescue (SAR). Some of these technologies may flow down to the regional and general aviation communities but, due to their initial cost, will be some time in coming.

In the meantime if you experience an emergency requiring a forced landing or ditching, how can you best ensure you have provided the SAR system with sufficient information for it to render assistance. This will largely depend upon the ability of the SAR system to respond and your actions in providing it with sufficient information to respond effectively.

Marshalling the Response

The coordination of a SAR response to an incident involving CASA or RA-Aus registered aircraft rests with Australian Search and Rescue (AusSAR) in Canberra. The word coordination is used as AusSAR has no allocated resources to respond to an incident and it seeks the assistance of response assets from the civil sector through standing or informal arrangements. When the civil sector cannot provide the resources or the available resources are unsuitable, AusSAR is then able to seek assistance from the Australian Defence Force.

A SAR incident is defined as a specific situation that causes the SAR system to be activated. In general terms, there are two parts to any SAR response with the first being the search and the second being the rescue. Initially, the degree of search planning is determined by the environment in the incident area, the accuracy of the reported location, the elapsed time since the incident occurred and the availability of suitable search assets. This process is informed by the amount and detail of intelligence that can be gained about the missing aircraft. The rescue plan is conducted in parallel and this is generally undertaken by fixed or rotary wing aircraft that have a standing arrangement with AusSAR or are a specialised emergency response unit located in the vicinity. For incidents on the water, marine craft may also be used.

With regard to search assets, aircraft are usually used due to their comparative speed that gives them the ability to cover large areas quickly. The number of aircraft involved will be determined by the size of the area to be searched, the capability and endurance of the aircraft being used and the characteristics of the area to be searched. AusSAR maintains an extensive database of general aviation, police, and specialised emergency service aircraft that are suitable for conducting searches.

While twin engine aircraft with good visibility, an accurate navigation system, possessing good endurance and the capacity to carry observers are ideal; it depends on the circumstances as to which aircraft are considered suitable especially in rural and remote areas and search operations to seaward. Some of the more recent larger searches have seen a variety of aircraft types and configurations used including single engine aircraft. While there is a mechanism to pay civil owner/operators on a case-by-case basis for SAR operations, there are occasions when private operators volunteer their services at no charge as a service to the aviation community. There are also many trained police, SES and volunteer observers around the country and they become an important part of any large scale SAR operation.

The timeliness of a response to an incident depends not only on the accuracy of information regarding the missing aircraft's flight intentions but also on the accuracy of information held in the AusSAR Aviation Database. AusSAR is interested in obtaining all aircraft details from all aircraft owners/operators and readers are asked to submit their details; a proforma for this purpose can be gained by contacting AusSAR. Any information provided will be subject to the Privacy Act 1988 provisions and will only be used for SAR and emergency response purposes. Please call AusSAR on 1800 815 257 for further details. AusSAR is also interested in non-licensed airfields especially those on properties around Australia. Again, a proforma for this purpose can be gained by contacting AusSAR.

AusSAR

GPO Box 2181

Canberra City ACT 2601

Telephone: 1800 815 257

Fax: 1800 622 153

5.7.5 Pilot pre-flight preparations

Building an Intelligence Picture

Now that we have the response organised, it's time to take stock about what preparations you have made to assist the situation if you are the unfortunate soul waiting for the SAR system to perform. In addition to your normal pilot-in-command responsibilities, which include regularly reviewing the Emergency Procedures Section of ERSA, the following points would seem appropriate if AusSAR is to build a rapid intelligence picture:

• How will your flight be reconstructed if you did you did not submit a flight plan to Airservices Australia, or another organisation, or leave a flight note with a responsible person?
• In the case of the latter, is the responsible person aware of the AusSAR contact number and the importance of last light regarding the conduct of an initial search?
• Did the flight plan or flight note include a destination or mobile telephone number, and the phone or mobile number of the pilot?
• Was there a SARTIME submitted to Airservices Australia?
• Is there a good description of your aircraft available (external appearance description with a recent colour photograph, equipment fit, emergency and survival equipment including whether an ELT is fitted or a Personal Locator Beacon (PLB) is being carried)?
• Is there someone aware of your experience, qualifications and aviation habits?
• How will your passengers and their points of contact be identified? Do the passengers have mobile phone numbers that can be used as an alternative means of contact?

Other Points of SAR Significance

While many aviators carry a PLB, they leave it in their flight bag in a place that is not easily reached while in flight. The briefing of passengers of its location and purpose may be appropriate. BASI recommends that you and your passengers dress for the terrain and not the destination. It is a sign of good airmanship to monitor 121.5 MHz before engine start and after engine shutdown to ensure that your ELT or PLB or others in the area are not active. All distress beacon detections are treated as distress situations and if you or your passengers inadvertently activate your beacon for longer than ten seconds then turn it off and advise AusSAR of the circumstances via ATS frequencies or telephone. There are no punitive measures for inadvertent activations and early advice will assist in the early resolution of a potential incident.

Lastly, if you have activated a distress beacon because you are in grave and imminent danger, if you are able don't forget to take measures to be a cooperative target for search aircraft by using signalling devices such as flares, etc, if available. The imprecision of homing devices mean that the general position can often be quickly determined but the exact position, especially in rugged and covered terrain such as that found on the eastern seaboard, can present major difficulties.

Conclusion

The coordination of the response to aviation SAR incidents is handled by AusSAR from the Canberra RCC and the effectiveness of the response depends not only on the effectiveness of the search but also on the measures taken by the pilot of the missing aircraft to assist AusSAR by leaving an intelligence trail from which the flight can be reconstructed for search planning purposes.

SAR alerting is carried out by a number of means with Airservices Australia being the primary advisory agency for aviation incidents for which Airservices Australia has introduced the centralised SARTIME database (CENSAR). A flight plan or flight note with a destination contact number is most important should an aircraft go missing. Early advice, especially in relation to last light, and good intelligence are both vital to the search planners. AusSAR remains committed to providing an effective SAR response service and it seeks your assistance to ensure that its resources are not dissipated on non-SAR incident responses.

STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)

ACMA – Australian Communications and Media Authority (managers of the RF spectrum)
ADF – Automatic direction finding equipment
ADS-B – Automatic dependent surveillance – broadcast
AERIS – Automatic en route information service (continuous broadcast network)
AFRU – Aerodrome frequency response unit
A/G – Air-to-ground (communication)
AIP – Airservices Australia Aeronautical Information Publication
AIP GEN – The general part of the AIP book
AIP ENR – The en route part of the AIP book
AM – Amplitude modulation
AMSA – Australian Maritime Safety Authority (reponsibilities include all search and rescue; see AusSAR)
ATC – Air traffic control sector of ATS
ATIS – Automatic terminal information system (continuous broadcast)
ATS – Air Traffic Services
AUF – Australian Ultralight Federation, now RA-Aus
AusFIC – Airservices Australian Flight Information Centre [1800 814 931]
AusSAR – AMSA's Australian Search and Rescue organisation
AWIB – Automatic weather information broadcast
AWIS – Automatic weather information system
AWS – Automatic weather station

CAA – Civil Aviation Act 1988
CA/GRS – Certified air/ground radio service
CAO – Civil Aviation Order
CAR – Civil Aviation Regulation
CASA – Civil Aviation Safety Authority
CASR – Civil Aviation Safety Regulation
CAVOK – [cav-okay] Ceiling and visibility better than the minimum VMC conditions for VFR flight
CB – The 40 UHF citizen's band channels between 476.425 and 477.400 MHz
CENSAR – AusFIC Centralised SARTIME database software — see SARWATCH
CL2006 – Current Radiocommunications (Aircraft and Aeronautical Mobile Stations) Class Licence
COM or COMMS – The aviation VHF communications band: 118.00 to 136.975 MHz
COSPAS – The Russian search and rescue satellite-aided tracking system
CTA – Control area
CTAF – [see-taff] Common traffic advisory frequency (in the vicinity of an airfield)
CTR – Control zone

ELB – Electronic locator beacon (obsolete system, not Cospas-Sarsat compatible)
ELT – Emergency locator transmitter (aviation distress beacon)
EPIRB – [e-perb] Emergency position-indicating radio (maritime distress) beacon
ERC-L – En Route Chart–low
ERSA – En Route Supplement–Australia
ETA – Estimated time of arrival

FIA – Flight information area
FIR – Flight information region (BN and ML)
FIS – Flight information service
Flightwatch – Callsign of Airservices Australia's on-request flight information service
FM – Frequency modulation

GHz – Gigahertz – 1 GHZ = 1 billion cycles per second
GNSS – Global navigation satellite system
GPS – Global positioning system

HF – The 12 aeronautical sub-bands, between 2850 and 22000 kHz, in the domestic and international high-frequency networks
HGFA – The Hang Gliding Federation of Australia

ICAO – International Civil Aviation Organisation
ID – Identification (callsign)
IFR – Instrument flight rules

kHz – Kilohertz: 1 kHz = 1 thousand cycles per second

LCD – Liquid crystal display
LED – Light emitting diode
LOS – Line of sight (distance)

MAYDAY – Prefix to an R/T distress broadcast
MTOW – [em-tow] Maximum take-off weight
MEM – Memory (electronic)
METAR – Routine aviation meteorological report
MHz – Megahertz: 1 MHz = 1 million cycles per second
Multicom – General airfield communications frequency: 126.7 MHz

NAV – Aviation VHF navigation facilities band: 108.1 to 117.975 MHz
NAV/COM – The inclusive aviation VHF band from 108.00 to 136.975 MHz
NDB – Non-directional (radio) beacon

OCTA – Outside controlled airspace

PAN-PAN – Prefix to a radiotelephony urgency broadcast
PCA – Planning Chart–Australia
PEP – Peak envelope power
PIC – Pilot in command
PLB – Personal locator (distress) beacon
POB – Persons on board
PROG – Program (microprocessor)
PTT – Press-to-talk (button or switch)

QNH – The mean sea level pressure derived from the barometric pressure at the station location

RA-Aus – Recreational Aviation Australia Inc
RCC – AusSAR's Rescue Coordination Centre, Canberra
RF – Radio frequency
RIS – Radar information service (replaced by SIS)
R/T – Radio telephony
RPT – Regular public transport

SAR – Search and rescue
SARSAT – Search and rescue satellite-aided tracking system
SARTIME – Time nominated by a pilot for the initiation of SAR action if a report has not been received by the nominated unit
SARWATCH – Air Traffic Services SAR alerting system based on position reporting, scheduled reportings and other procedures for IFR flights but also includes VFR flights operating under ATS airways clearance or SIS
SIS – ATS radar and ADS-B surveillance information service replacing RIS

TAF – Aerodrome weather forecast
TTF – Trend forecast

UHF – Ultra high frequency band: 300 MHz to 3 GHz
Unicom – Ground-based private operator aerodrome communications frequency
UTC – Coordinated Universal Time

VHF – Very high frequency band: 30 MHz to 300 MHz
VFR – Visual flight rules
VMC – Visual meteorological conditions
VNC – Visual navigation chart
VOR – VHF omni-directional radio range
VTC – Visual terminal chart