Mayday

distress signal

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June 30, 2026

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"Mayday" is an internationally recognized radio distress signal, primarily used by aircraft and boats. It is pronounced like the French phrase m'aider, meaning "help me".123

The signal was adopted in 1923 to replace the Morse code distress signal "SOS" for radiotelephone communications. While SOS was effective for telegraphy, "Mayday" was chosen for radio because it is a short, easily understood word that is less likely to be mistaken for other sounds. The new distress call was tested and adopted widely, including in the United States by 1927.12

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distress signal
…or the spoken word “Mayday” (pronounced like the French m’aider, “help me”), by radiotelephone. Distressed vessels may also actuate alarms of other vessels by a radio signal consisting of a series of 12 four-second dashes or by a radiotelephone signal consisting of two tones alternately transmitted for 30 to…
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…or the spoken word “Mayday” (pronounced like the French m’aider, “help me”), by radiotelephone. Distressed vessels may also actuate alarms of other vessels by a radio signal consisting of a series of 12 four-second dashes or by a radiotelephone signal consisting of two tones alternately transmitted for 30 to…
Read More