MAYDAY on the AFIS frequency while an ELT sweeps 121.5
At 1432 UTC the KDRX aerodrome flight information service, staffed by a single watchkeeper, is working three aircraft on 118.300 when a continuous swept-tone signal appears on the 121.5 receiver, characteristic of an ELT. Twenty seconds later an aircraft on 118.300 transmits 'MAYDAY MAYDAY MAYDAY, KDRX, engine failure, twelve miles north of the field, descending, one person on board'. It is a light single-engine aircraft, VFR, in contact with the FIS but with no other ATS unit. A second aircraft on the frequency offers to relay and asks whether it should change to 121.5. The nearest approach control unit is 60 NM away, and the rescue coordination centre can be reached by telephone. The site has no radar and no direction-finding equipment. The watchkeeper must decide what to transmit, on which frequency, and in what order.
1. Set out the watchkeeper's actions in order of priority for the first two minutes, with reasons.
Read the worked answer
Acknowledge the MAYDAY on 118.300 and keep the aircraft there. Reply immediately using the callsign, confirm that the distress has been received, and do not instruct a change of frequency. 121.5 is currently unreadable because of the swept tone, so a transfer would risk losing the one channel that is working.
Extract the minimum essential information in one pass: nature of the emergency, position, level or height, heading, persons on board, fuel or endurance, and intentions (forced landing site, ejection, ditching). Then let the pilot fly.
Alert the rescue coordination centre by telephone and the parent approach control unit, passing exactly what the pilot said. KDRX provides flight information, not control, so it cannot clear traffic or guarantee separation; its job is to alert and to relay, and it must not imply an capability it does not have.
Protect the frequency. Instruct other aircraft to cease transmitting except for their own emergencies, and move the two other aircraft off 118.300 if they can be handled elsewhere.
Start the clock and write it down. Time of the MAYDAY, time acknowledged, time the RCC was alerted, and the name of the person at the RCC. Times taken later from memory are worthless to an investigation.
The ELT comes after the voice distress, not before.
2. Write the transmissions the watchkeeper should make: the reply to the MAYDAY, the instruction to other traffic, and the handling of the relay offer. Justify the choice of frequency in each case.
Read the worked answer
Reply to the distressed aircraft (on 118.300):
G-ABCD, KDRX, MAYDAY RECEIVED. Report position, heading, level and intentions. - short, standard, no questions the pilot cannot answer while flying.
Silencing other traffic (on 118.300):
ALL STATIONS, KDRX, CEASE TRANSMITTING, DISTRESS TRAFFIC. An all-stations call in plain language is unambiguous and needs no imported maritime terminology. Where the two other aircraft can safely be handed to another frequency or to the approach unit, do that rather than leave them holding on a frequency they must not use.
Relay offer: accept it only if it adds value. The distressed aircraft is already in direct two-way contact with the station that is handling the emergency, so a relay adds a second voice and a second chance of error. A useful compromise is to keep the relay aircraft on 118.300 as a listening watch and to task it to pass information to the approach unit if KDRX loses contact. If a relay is genuinely used, it must be prefixed MAYDAY RELAY three times, identify the relaying station, and carry the distress information verbatim. The relay aircraft should not be sent to 121.5: the frequency is blocked by the ELT, and sending a second aircraft there removes a useful observer from the working channel.
3. How should the 121.5 swept tone be handled, including the possibility that it relates to the same aircraft? What must the log contain?
Read the worked answer
Treat the tone as an independent event until proven otherwise. It may be a false alarm, a test, an inadvertent activation on the ground, or the ELT of the aircraft now declaring an emergency - the watchkeeper cannot tell, and assuming any of these would be a judgement made without evidence.
Actions:
- Note the time it started, whether it is steady or sweeping, and whether signal strength rises or falls. Rising strength suggests a beacon on an approaching aircraft.
- Do not transmit test counts or carrier on 121.5 while it is active; a transmission there may mask a weak voice distress from the same or another aircraft.
- Report it to the rescue coordination centre by telephone together with the MAYDAY, making clear they may be the same event.
- Keep the 121.5 receiver audible and monitored at the operating position, not muted.
- If a voice appears on 121.5, answer it immediately, even if the emergency on 118.300 is still running.
Log entries: time of the swept tone and its cessation; time of the MAYDAY, callsign and full text; each transmission made; each unit alerted, with the name of the person spoken to; the relay arrangements; the time contact was lost or the emergency concluded. Log in UTC, and never backdate an entry.