SOS

An internationally recognised Morse-code distress signal formed by three dots, three dashes and three dots sent as one continuous sequence.

SOS was selected for its distinctive radio-telegraph pattern and is not formally an abbreviation for ‘Save Our Souls’ or ‘Save Our Ship’. It can be conveyed by radio telegraphy, light or another signalling method capable of reproducing the sequence.

Modern maritime voice distress uses MAYDAY and GMDSS alerting uses DSC, satellite and beacon systems, but SOS remains a recognised distress signal. It should be used only when grave and imminent danger requires immediate assistance and accompanied by identity, position and nature of distress whenever possible.

• SOS was proposed in 1906
  The signal “SOS” was chosen at the International Radiotelegraph Conference in Berlin because:
  • It is simple to transmit and recognise in Morse code (· · · – – – · · ·).
  • It is unambiguous and easy to distinguish from other signals.
• SOS became mandatory in 1908
  Starting July 1, 1908, all ships equipped with wireless communication were required to use SOS as the universal distress signal.