MAYDAY (DISTRESS CALL)

A Mayday situation is one in which a vessel, aircraft, vehicle, or person is in grave and imminent danger and requires immediate assistance. Examples of "grave and imminent danger" in which a mayday call would be appropriate include fire, explosion or sinking.

Mayday calls can be made on any frequency, and when a mayday call is made no other radio traffic is permitted except to assist in the emergency. A mayday call may only be made when life or craft is in imminent danger of death or destruction.

'Mayday' calls are made by radio, such as a ship or aircraft's VHF radio. Although a Mayday call will be understood regardless of the radio frequency on which it is broadcast, first-line response organisations, such as the coastguard and air traffic control, monitor designated channels: marine MF on 2182 kHz; marine VHF radio channel 16 (156.8 MHz); and airband frequencies of 121.5 MHz and 243.0 MHz. A Mayday call is roughly equivalent of a morse code SOS, or a telephone call to the emergency services.

When they receive a Mayday call the coastguard may launch lifeboats and helicopters to assist the ship that is in trouble. Other ships that are nearby may divert course to assist the vessel broadcasting the Mayday.

Making a hoax Mayday call is a criminal act in many countries because of the danger to the rescuers' lives that a search-and-rescue operation can create, as well as the very high costs of such rescue efforts. For example, making a false distress call in the U.S. is a federal crime carrying sanctions of up to six years imprisonment, and a fine of $250,000[2].

The coastguard can be contacted in situations that are not emergencies (out of fuel, etc.) by calling 'Coastguard, Coastguard, Coastguard, this is (name of vessel)', on VHF channel 16. In many countries special training and a licence are required to use a mobile radio transmitter legally, although anyone may legally use one to summon help in a real emergency.

The recommended distress call format includes the word MAYDAY spoken three times (repeated twice), followed by the vessel's name or callsign, also spoken three times, then MAYDAY and the name or callsign again. Vital information, including the position, nature of the emergency, assistance required and the number of people on board, should follow. A typical message might be:

"MAYDAY, MAYDAY, MAYDAY, this is NONSUCH, NONSUCH, NONSUCH. MAYDAY, NONSUCH. Position 54 25 North 016 33 West. My boat is on fire and sinking. I require immediate assistance. 4 people on board, are taking a lifeboat. OVER."

If a Mayday call cannot be sent because a radio is not available a variety of other distress signals and calls for help can be used. A Mayday can be sent on behalf of one vessel by another, using a convention called a Mayday Relay.

MAYDAY RELAY CALL

A Mayday relay call is made by one vessel on behalf of a different vessel which is in distress. If a vessel makes a Mayday call and it is not acknowledged by the coastguard after a single repetition and a two-minute wait a vessel receiving the Mayday call should attempt to contact the coastguard on behalf of the Mayday vessel by broadcasting a Mayday Relay on their behalf.

A Mayday Relay call should use the callsign of the transmitting vessel but give the name and position of the Mayday vessel.

Mayday Relay calls can be used to summon help for a vessel which is either too far offshore to contact the coastguard directly or without radio capabilities (though most vessels above a certain size or crew complement are legally required to carry two-way radio equipment, such equipment can potentially be damaged or destroyed).