47 CFR 80.314: Distress communications.

(a) The international radiotelephone distress signal consists of the word MAYDAY, pronounced as the French expression “m'aider”.

(b) These distress signals indicate that a mobile station is threatened by grave and imminent danger and requests immediate assistance.

(c) The radiotelephone distress call consists of:

(1) The distress signal MAYDAY spoken three times;

(2) The words THIS IS;

(3) The call sign (or name, if no call sign assigned) of the mobile station in distress, spoken three times;

(4) Particulars of the station's position;

(5) The nature of the distress;

(6) The kind of assistance desired; and

(7) Any other information which might facilitate rescue, for example, the length, color, and type of vessel, or number of persons on board.

(d) The procedures for canceling false distress alerts are contained in § 80.335.