It’s a word used around the world to make an emergency call via radio communications in both a ship or a plane. The call has to be said three times in a row loudly- Mayday! Mayday! Mayday! – to confirm it as not a mistake during the noisy conditions in the connection. Followed by needed potential information including; the aircraft’s identity, the emergency situation, location or the last known location, current weather condition, the remaining fuel, the type of needed help, and the number of persons in danger.
These emergency calls started to be used officially as an emergency call in 1948, which was the idea of Frederick Mockford who was a senior radio officer at Croydon Airport in London. The word came from the French word “m’aider” which means “help me”. A mayday call is necessary in case the plane lost radio communications. Mayday call cannot be taken as a joke, in the U.S it’s illegal to make a fake one, doing this lead to jail for 6 months and is subjected to 250’000$.
Following the Mayday call by the Vistara pilot, a company spokesperson said, “Flight UK944 operating Mumbai-Delhi on July 15, 2019, started a diversion to Lucknow because of bad weather over Delhi. However, over Lucknow, the visibility suddenly startled and a safe landing was not possible. The crew then thought of alternative airfields, including Kanpur and Prayagraj to land in better weather condition”. The Lucknow Air Traffic Control reported to the crew that the weather in Lucknow had improved, then the pilot decided to return to the city.
Other emergency calls
In less than life-threaten situations there are other signals. For instance; Pan-Pan from the French word Panne which means “Breakdown” refers to medical or mechanical situations.
Another signal is “Securite” from the French word sécurité, which means “safety”, this conveys security situations like bad weather or navigation hazards.
Source: aviationforaviators.com