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Safety and emergency communication procedures


Rev. 26 — page content was last changed 1 June 2010; additional information on Cospas-Sarsat

Page editing by RA-Aus member Dave Gardiner www.redlettuce.com.au
Coping with emergencies &
VHF radiocommunications
  

Module content


When a pilot is experiencing in-flight difficulties it is advisable to inform others as early as practical and to advise whether the pilot considers the situation to be an emergency or something less. The VHF frequency on which a distress call (a MAYDAY transmission) or an urgency message (a PAN-PAN transmission) is made, should be that which is most likely to provide a quick response from a responsible person.

In addition satellite radio distress beacons may be used, as a means of last resort, to alert the Australian Search and Rescue organisation that an aircraft's occupants are in 'grave and imminent danger' on the surface.

The material in this module of the VHF radiocommunications guide covers part of the RA-Aus radio operator's endorsement syllabus listed in the Operations Manual section 3.08.

This module also forms part of the 'Coping with Emergencies' Guide.


6.1 Communications when in difficulties

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 normally controllable, visibility is okay and the area is clear terrain with a normal rural population density and road infrastructure, then the landing will not be life-threatening. 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.

  • 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 risk of 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'aidez (help me), was adopted in 1927 as the standard radiotelephony distress call.

In between these two extremes 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 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 Flightwatch on the flight information area frequency. If 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). 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 communicate.

The pilot who is encountering difficulties might decide to request assistance from flight information services — Flightwatch if contactable — 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:
  • BRISBANE CENTRE FLIGHTWATCH
  • THRUSTER ZERO TWO EIGHT SIX
  • EXPERIENCING NAVIGATION DIFFICULTIES IN DETERIORATING VISIBILITY
  • REQUEST NAVIGATION ADVISORY


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.

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.
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 it is seen 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.

  • Flightwatch 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 number one 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 communications.

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 a Flightwatch 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 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 telephone may also be useful in advising your situation to others. In Australia the cellular mobile telephone service operates on frequencies in the 900 MHz band. Be aware that the current ACMA cellular mobile class licence 'does not authorise the operation of a station (i.e. a mobile 'phone) that is in an airborne aircraft.' This is because an actived telephone may cause channel interference across cells, because of the altitude of the device. However, in an emergency, safety has priority and pilots may contact the ATC centres by mobile phone; the telephone numbers of the ATC centres and the SAR hotline are given in ERSA GEN-FIS. Store that number in your 'phone.

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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.



6.2 Distress beacons and AusSAR

ELTs, EPIRBs and PLBs
When on the ground and in a life-threatening situation, the pilot may activate a radio distress beacon. The signal from the beacon will be detected by the specialised search and rescue satellites — Sarsat (Search And Rescue Satellite Aided Tracking system) and the Russian Cospas. The Cospas-Sarsat satellites 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 — RPT 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 (perhapd by a g-switch) under a high-impact deceleration; or they can be manually activated by the pilot.

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 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 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 Australia — 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.)

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 — three times per second — with a swept tone, audible via a VHF transceiver. The 121.5 or 243.0 MHz transmission is used as a 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 — which is a bit hard on bushwalkers.

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.

GME's MT410G PLB 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 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. The 406.025 MHz beacons also transmit an 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 within a 30 hexadecimal character distress message. That message is retransmitted by the satellite to the two AMSA ground stations. The identity code must be registered with 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] — this will be compulsory under new CASA regulations.

*Hexadecimal refers to a version of computer coding that uses a base of 16 numeric and alpha characters, any of which can be represented using just four binary digits rather than the 8-bit byte normally used. The 16 characters or markers are 0–9 plus A–F. All PLBs must have an individual 15 character 'Hex-ID' already marked on the unit as purchased. Similarly, aircraft transponders use octal coding with only three binary digits to represent any of the eight numerics 0–7.
Requirement to carry 406.025 MHz beacons
The requirement for an Australian aircraft to carry an approved distress beacon or emergency locating device is stated in CAR 252A (as amended 1 February 2009). However, CAOs 95.10, 95.32 and 95.55 currently allow an exemption from CAR252A for RA-Aus aircraft. Thus, RA-Aus aircraft are currently not required to carry an ELT, though many of our members wisely do so. However, the CAR 252A exemption will be removed from those CAOs sometime during 2010 (the same effect will occur when CASR Part 103 is finally promulgated), so EVERY two-place RA-Aus aircraft operating beyond 50 nm from their starting point will then be 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 (for example, the MT410G costs about $650) and register that beacon as soon as possible. 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.

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. 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.'

Cospas-Sarsat rescues in 2008


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

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6.3 Aircraft radar beacon transponders

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

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. Primary radar surveillance 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.

In addition, the response from transponders fitted to smaller civilian aircraft normally consists of a 12-bit octal identity/status code plus a 12-bit octal 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 3 A/C (or Mode A/C) transponders.

The transponder receives the Mode C altitude data from an altitude encoding altimeter or from a blind encoder; the latter probably being an electronic device with a pressure transducer connected to the static vent feed. Both types of units send pressure altitude not altimeter-indicated altitude. Some encoders are also capable of supplying altitude data to a GPS — 'baro-aiding'.

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 identity code 'squawked' by VFR aircraft is '1200' until radio contact with Air Traffic Services, who might then instruct the pilot to squawk an assigned individual code; e.g. 4367. The maximum number of pilot-selected identity codes available for assignment at any one time is 4096.

All transponders have an 'identify' (IDENT) button which, when pressed, momentarily adds an additional bit to the identity code; that causes the aircraft's 'paint' to brighten on the controller's display. To identify a particular aircraft among those squawking '1200' the controller will request the pilot to "squawk ident"; i.e. push the 'ident' button.

The Mode A/C surveillance system is very limited. The transponders carried by regular passenger transport aircraft use a 24-bit identity code allowing a total of 16.8 million individual addresses. Thus every aircraft can be permanently assigned a unique address, perhaps based on the aircraft's country of registration and registration number. Consequently, those aircraft can be selectively addressed by ground stations or other aircraft. This message format is called Mode S (for 'selective address') but the transponders also have the normal Mode A/C functions.

Currently, in Australia, the main Mode S transponder function is to allow aircraft equipped with Traffic Alert and Collision Avoidance Systems [TCAS] to 'talk' directly with each other, thereby enabling mutual resolution of potential traffic conflicts. 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 radars are of the fast, single_pulse interrogation type. Many of the Australian SSRs are not mono-pulse radars and are being replaced.

GPS-based technologies that promise a substantial change in airborne communication, navigation and surveillance techniques are nearing fruition; among these is Automatic Dependent Surveillance–Broadcast [ADS-B]. That new satellite-based surveillance and traffic management system is currently being implemented for upper-level airspace.
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 ultralights — 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. An ultralight pilot 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. There may be occasions when a controller requests you to "squawk ident"; i.e. push the button on the transponder marked IDENT. This causes the aircraft's 'ID' on the controller's screen to brighten or flash for a few seconds and thus aid positive identification. 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 web site.
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 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. AD/RAD/43 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.

[ The next section in the airmanship and safety sequence describes Microscale meteorology and atmospheric hazards ]




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6.4 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 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




The next section of the Coping with Emergencies Guide is a further discussion of aviation distress beacons written by David McBrien of AusSAR.

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Groundschool – VHF Radiocommunications Guide

| Guide content | Abbreviations and acronyms |

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

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

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


Next – Aviation distress beacons The next section of the VHF radiocommunications guide is a further discussion of aviation distress beacons written by David McBrien of AusSAR.


Copyright © 2003 — 2009 John Brandon     [contact information]