MAYDAY — Distress
MAYDAY is the international distress call, from French "m'aider" (= "help me"). It is spoken three times at the start of every distress transmission.
Source: ICAO Annex 10 Volume II, Section 5.3 Distress and Urgency Communications; ICAO Doc 9432 Chapter 9; ITU Radio Regulations.
Definition of distress (Annex 10 Vol II)
Distress = "A condition of being threatened by serious and/or imminent danger and of requiring immediate assistance." So there must simultaneously be a serious / imminent threat and immediate assistance required.
When to use MAYDAY?
MAYDAY is used in an actual threat to life — i.e. when:
- Immediate assistance is required.
- Loss of aircraft is imminent.
- Personal injury is imminent.
Classic examples:
- Engine failure with no landing site.
- Fire on board.
- Structural defect.
- Medical emergency on board (pilot or passenger).
- Pilot disoriented / pilot incapacitated.
- Fuel exhaustion imminent.
Frequency
- Primary frequency: current one (Tower, Approach, Centre, FIS).
- International emergency frequency: 121.500 MHz — when primary fails.
- Squawk 7700 on transponder — immediately.
MAYDAY content — mandatory elements (ICAO Annex 10 Vol II §5.3.2.1)
A distress message should contain as many of the following elements as possible — in this order:
| No. | Element | Content |
|---|---|---|
| [1] | Distress signal | "MAYDAY" × 3 |
| [2] | Station addressed (if time permits) | e.g. "Munich Tower" |
| [3] | Own callsign | DEMRA × 3 |
| [4] | Nature of distress | type of emergency (engine failure, fire, smoke …) |
| [5] | Intentions | what the pilot will do (forced landing, diverting …) |
| [6] | Position, altitude, heading | lat/lon or relative; level; course |
| [7] | Pilot's qualification (optional) | e.g. "PPL, no IFR" — relevant at IMC entry |
| [8] | Any other useful information | POB (persons on board), fuel in hours, aircraft colour, help requested (ambulance, fire brigade) |
Example — engine failure
"Mayday Mayday Mayday, Munich Tower, Delta Echo Mike Romeo Alpha Delta Echo Mike Romeo Alpha Delta Echo Mike Romeo Alpha, engine failure, descending for emergency landing in field, 10 NM south of Augsburg, level 3000 ft, heading 270, 3 persons on board, 2 hours fuel remaining, request fire brigade on standby."
Shortened versions
Under extreme time pressure the call may be reduced:
- "Mayday Mayday Mayday, DEMRA, engine failure, going down."
→ Key: MAYDAY × 3 and callsign must be there.
Typical ATC response
"DEMRA, Mayday acknowledged, state your intentions / request your position."
or: "DEMRA, Mayday roger, all stations stop transmitting, frequency reserved for emergency."
Traffic behaviour during Mayday
- Pilot in mayday has absolute priority.
- Other traffic stays silent on the frequency until the emergency is over ("silence imposed").
- If another pilot hears a Mayday call: do not answer, do not transmit.
- Frequency silence is requested by the pilot in distress or by ATC with "Stop transmitting, Mayday"; lifted with "Distress traffic ended".
Ending the emergency
When the situation is resolved:
- Pilot reports: "Cancel Mayday, DEMRA."
- ATC confirms: "DEMRA, Mayday cancelled, contact Information 124.45 for normal service."
Important notes
- MAYDAY is mandatory in an emergency — pilot must never hesitate.
- False MAYDAY calls are an offence (emergency-call abuse).
- In language confusion: English is always accepted, even when local language is normally spoken.
Cross-reference
- Subject 070 Lesson "Emergency Procedures" for tactical action.
- Subject 070 Lesson "Engine Failure in Cruise" for specific scenarios.
- Subject 090 Lesson "PAN PAN" for the urgency level one step below.