Why Is “Mayday” the International Distress Call?

“Mayday!” is an international distress call used by airplane pilots, boat captains, and some emergency response personnel. The U.S. Coast Guard deals with roughly 25,000 distress calls every year, some of which involve the “mayday” code. Why not just use the standard "SOS" call that ship captains used when they were in trouble? Ships communicated through telegraph using Morse code, and this technology made "SOS" (three dots, three dashes, three dots) unmistakable. By contrast, aircraft pilots used radio calls, and "SOS," owing to its consonants, could be misheard as other letters, like "F.” Frederick Stanley Mockford, a senior radio officer in London, was put in charge of finding an appropriate code word. He reasoned that because so much of the air traffic flew between Croydon and Le Bourget Airport in Paris, it might make sense to use a derivative of a French word. He came up with "mayday," the French pronunciation of "m'aider" ("help me"). The U.S. formally adopted "mayday" as a distress signal in 1927, but due to radio interference and loud ambient noise, pilots are told to repeat the word three times: "Mayday, mayday, mayday.” Each year, the Coast Guard has to deal with hoax calls using the distress signal. People who abuse this system can be jailed for up to 10 years and fined $250,000.