The pilots of Vistara flight UK944 from Mumbai to Delhi on 15 July issued a Mayday call as the flight, diverted from New Delhi to Lucknow due to bad weather, was low on fuel. Mint charts the history of the distress call signal and its relevance today.

What is a Mayday call?

Mayday is a distress call that is used to signal a life-threatening emergency, usually on a ship or a plane, although it may be used in a variety of other situations. A typical distress call will start with the word “Mayday" being said three times in a row so that it is not mistaken for another similar-sounding word or phrase. This is followed by relaying the information that rescuers would need, including the nature of the emergency, the location or last known location, current weather, type and identity of craft involved, fuel remaining and the number of people in danger. The distress call has absolute priority over all other transmissions.


How did it originate?

The Mayday call originated in the 1920s. A senior radio officer at London’s Croydon Airport in London, Frederick Stanley Mockford, was the first to use this signal to indicate emergency situations. Mockford was asked by his seniors to think of a word that would indicate distress and would easily be understood by all pilots and ground staff during an emergency. As much of the traffic at Croydon airport at that time was to and from Le Bourget Airport in Paris, Mockford proposed the expression “Mayday" derived from the French word “m’aider" that means “help me" and is a shortened form of “venez m’aider", which means “come and help me".

What was used earlier?

SOS, short for “save our souls" sent by Morse code, predates the use of Mayday. In 1927, the International Radiotelegraph Convention adopted Mayday as the radiotelephone distress call in place of SOS.

What are the other distress calls used?

One popular emergency call is the Pan-pan, derived from the French word “panne" that means “a breakdown". It indicates an urgent situation such as a mechanical failure or a medical problem. A Pan-pan call is generally of a notch lower than a Mayday in terms of threat. Pan-pan is the international standard urgency signal that someone aboard a boat, ship, aircraft or other vehicle has an urgent situation, but which, for the time being, does not pose an immediate danger to anyone’s life or to the vessel itself.

What is the format for relaying a Mayday call?

The pilot or ship’s captain must call out “Mayday, Mayday, Mayday" loudly. Following this, the pilot has to read aloud the name of his station, aircraft/ship call sign and type, nature of emergency, weather, pilot’s intentions and/or requests, present position and heading, and if lost then the last known position and heading and time when aircraft was at that position, altitude or flight level, fuel remaining in minutes, the number of people on board, followed by any other useful information.

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