Mayday is the internationally recognized voice radio distress signal, reserved exclusively for situations of grave and imminent danger where immediate assistance is required.
When Mayday Is Used
Mayday is used only for genuine life-threatening emergencies — a vessel sinking, fire out of control, person overboard with immediate danger, or similarly serious situations. It is never used for non-urgent matters; misuse of distress signals is a serious offense.
Standard Mayday Format
A proper Mayday transmission follows a specific structure to ensure clarity:
- “Mayday, Mayday, Mayday” — said three times
- Vessel name/call sign — said three times
- Position — as precise as possible (GPS coordinates or bearing/distance from a known point)
- Nature of distress — what’s actually happening (fire, sinking, collision, etc.)
- Assistance required
- Number of persons aboard
- Any other relevant information
Mayday vs Pan-Pan vs Sécurité
These three represent a hierarchy of radio urgency:
- Mayday — grave and imminent danger, life-threatening
- Pan-Pan — urgent situation, not immediately life-threatening (a Pan-Pan call still requires priority attention but doesn’t indicate the same immediate danger)
- Sécurité — safety message, such as a navigational warning, not an emergency at all
GMDSS Digital Distress Alerting
Modern GMDSS equipment can also transmit a digital distress alert (DSC) automatically including position data, complementing or preceding a voice Mayday call.
Exam Relevance
Mayday format, correct usage, and the distinction from Pan-Pan and Sécurité are core GMDSS and Communication topics in deck officer competency exams.