A distress signal, also known as a distress call, is an internationally recognized means for obtaining help.Distress signals are communicated by transmitting radio signals, displaying a visually observable item or illumination, or making a sound audible from a distance.. A distress signal indicates that a person or group of people, ship, aircraft, or other vehicle is threatened by …

SOS is a Morse code distress signal ( ), used internationally, that was 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.