Distress signals

SOS is a Morse code distress signal (), used internationally, originally established for maritime use. In formal notation SOS is written with an overscore line (), to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no spaces between the letters. In International Morse Code three dots form the letter "S" and three dashes make the letter "O", so "S O S" became a common way to remember the order of the dots and dashes. IWB, VZE, 3B, and V7 form equivalent sequences, but t

Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications.

thumb|upright=1.35|Illumination flares being used during military training exercises thumb|upright=1.35|Flares being fired from a ship during a fleet review

internationally recognized means for obtaining help

The radiotelephony message PAN-PAN is the international standard urgency signal that someone aboard a boat, ship, aircraft, or other vehicle uses to declare that they need help and that the situation is urgent, but for the time being, does not pose an immediate danger to anyone's life or to the vessel itself. This is referred to as a state of "urgency". This is distinct from a mayday call (distress signal), which means that there is imminent danger to life or to the continued viability of the vessel itself. Radioing "pan-pan" informs potential rescuers (including emergency services and other c

unexpected, sudden stopping of the engine turning, usually brought about accidentally

radio frequency on the marine VHF radio band

radio frequency designated for emergency communication