- ''See: May Day for the May 1 celebration.
is one of several emergency- and distress-related code words from the French language
used internationally as a distress signal
- Mayday (m'aidez help me!) means that someone is in danger of death and needs immediate assistance.
- Pan (panne a breakdown) indicates trouble, but not mortal danger, such as a man overboard not being attacked by sharks. It is usually transmitted as Pan Pan and repeated three times. The suffix medico is added to indicate a medical problem (Pan Pan medico, repeated three times).
- Securitay (sÚcuritÚ) indicates a message about safety, such as an approaching thunderstorm.
- Seelonce (silence) means that no one else may talk on the channel.
- Seelonce feenee (silence finie silence finished) means that others may now use the channel. The word prudonce (prudence caution) can also be used to allow restricted working to resume on that channel.
Unless you are a licensed radio operator or nautical or flight officer, never
use the keyword "MAYDAY" unless you are aboard a vessel or aircraft which is in immediate danger of sinking or crashing! You may endanger the lives of rescuers tens or hundreds of miles away if you do. People in helicopters and other aircraft will
respond to a MAYDAY call with limited fuel supplies and risk crashing in order to pinpoint your location! This has caused fatal crashes several times in open ocean and in the Canadian and Alaskan outback.
See also: call for help, SOS, distress signal