MAYDAY, PAN PAN and message priority for the ROC-A

Radio traffic is not first come, first served. Some messages always go first, and every ROC-A holder must know how to send, relay and answer an emergency call.

Order of priority

1. Distress (MAYDAY)
2. Urgency (PAN PAN)
3. Communications about radio direction-finding
4. Flight safety messages, such as ATC instructions
5. Meteorological messages
6. Flight regularity messages, such as company schedule changes

A station with a distress, urgency or safety message may interrupt lower-priority traffic at any time. In air-ground communications, the ground station controls the exchange.

MAYDAY or PAN PAN?

MAYDAY (distress) is for grave and imminent danger that needs immediate assistance: an uncontrolled fire, a forced landing, structural failure. Distress traffic has absolute priority.

PAN PAN (urgency) is for a condition that affects the safety of an aircraft or person but does not need immediate help: being unsure of your position with fuel to spare, or a sick passenger. Both signals are spoken three times.

The distress message

Send it first on the frequency in use. If nobody answers, repeat it on 121.5 MHz or any other frequency you can use. Give as much as time allows, in this order:

1. MAYDAY MAYDAY MAYDAY
2. Call sign
3. Nature of the distress and the help you need
4. Intentions of the pilot-in-command
5. Position, altitude and heading
6. Persons on board and any injuries

After the first call, say MAYDAY once at the start of every transmission about the distress. Select transponder code 7700 if you have one.

When you hear a MAYDAY

Stop any transmission that could interfere and keep listening. If the call is not acknowledged and you can help, relay it: "MAYDAY RELAY" three times, "THIS IS", your call sign, then MAYDAY and the message.

An acknowledgement follows a fixed pattern: MAYDAY, the distressed station's call sign three times, THIS IS, your call sign three times, RECEIVED MAYDAY.

The station in distress, or the station controlling the distress traffic, may impose silence on others. When it is over, the controlling station announces DISTRESS TRAFFIC ENDED. If your own emergency is solved, cancel it so rescuers are released.

Signal checks

A test transmission lasts no more than 10 seconds and includes your call sign. Readability is reported from 1 to 5: 1 unreadable, 2 readable now and then, 3 readable with difficulty, 4 readable, 5 perfectly readable.