MayDay - Air Crash Investigation [S4-E7] Out of Sight (HD)

It is used to signal a life-threatening emergency primarily by aviators and mariners, but in some countries local organizations such as firefighters, police forces, and transportation organizations also use the term. The call is always given three times in a row ("Mayday Mayday Mayday") to prevent its being mistaken for some similar-sounding phrase under noisy conditions, and to distinguish an actual Mayday call from a message about a Mayday call. - bsocially