Definition
The international radiotelephony distress signal used by a pilot to declare a life-threatening emergency requiring immediate assistance. It is spoken three times in succession ('Mayday, Mayday, Mayday') at the start of the transmission to alert ATC and any listening station that the aircraft is in grave and imminent danger.
Plain English
The spoken word a pilot uses on the radio to say there is a serious emergency and the flight needs help right away. Saying it three times in a row makes sure everyone listening knows it is a true emergency call and not regular chatter.
Context Anchor
Heard or transmitted on the radio during an emergency, usually at the start of a distress call to air traffic control or other aircraft.
Derivation
From the French phrase 'm'aider' (short for 'venez m'aider'), meaning 'come help me.' It was chosen in the 1920s because it sounded clear over noisy radios and could not easily be confused with other words.
Why Pilots Care
It grants the flight immediate priority handling, clears other traffic, and triggers emergency services and search-and-rescue coordination.
Intuition Check
Mayday does not mean any aircraft problem or inconvenience. It is reserved for a serious, immediate danger where help is needed now.
Example Sentence 1
After the engine quit, the pilot keyed the mic and called, 'Mayday, Mayday, Mayday — Cessna Six-Two-Three Alpha, engine failure, gliding to land.'
Example Sentence 2
After declaring Mayday, the controller cleared all other traffic and gave priority vectors to the nearest suitable runway.