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COLREGs trainerAnnexes

Annex IV

Distress Signals

Signals indicating distress and need of assistance.

1: Signals indicating distress

The following signals, used or exhibited together or separately, indicate distress and need of assistance: (a) a gun or other explosive signal fired at intervals of about a minute; (b) a continuous sounding with any fog-signalling apparatus; (c) rockets or shells throwing red stars, fired one at a time at short intervals; (d) a signal made by any signalling method consisting of the group · · · – – – · · · (SOS) in the Morse Code; (e) a signal by radiotelephony consisting of the spoken word "Mayday"; (f) the International Code Signal of distress indicated by N.C.; (g) a square flag with, above or below it, a ball or anything resembling a ball; (h) flames on the vessel (as from a burning tar or oil barrel, etc.); (i) a rocket parachute flare or a hand flare showing a red light; (j) a smoke signal giving off orange-coloured smoke; (k) slowly and repeatedly raising and lowering arms outstretched to each side; (l) a distress alert by means of digital selective calling (DSC) transmitted on: (i) VHF channel 70, or (ii) MF/HF on the frequencies 2187.5 kHz, 8414.5 kHz, 4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz; (m) a ship-to-shore distress alert transmitted by the ship’s Inmarsat or other mobile satellite service provider ship earth station; (n) signals transmitted by emergency position-indicating radio beacons; (o) approved signals transmitted by radiocommunication systems, including survival craft radar transponders.
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Wording follows the International Regulations as printed in the US Coast Guard Navigation Rules handbook (2024), with British spelling, and is shortened in places. Download the rules

Read the whole of Annex IV on one page

1: Signals indicating distress

The following signals, used or exhibited together or separately, indicate distress and need of assistance: (a) a gun or other explosive signal fired at intervals of about a minute; (b) a continuous sounding with any fog-signalling apparatus; (c) rockets or shells throwing red stars, fired one at a time at short intervals; (d) a signal made by any signalling method consisting of the group · · · – – – · · · (SOS) in the Morse Code; (e) a signal by radiotelephony consisting of the spoken word "Mayday"; (f) the International Code Signal of distress indicated by N.C.; (g) a square flag with, above or below it, a ball or anything resembling a ball; (h) flames on the vessel (as from a burning tar or oil barrel, etc.); (i) a rocket parachute flare or a hand flare showing a red light; (j) a smoke signal giving off orange-coloured smoke; (k) slowly and repeatedly raising and lowering arms outstretched to each side; (l) a distress alert by means of digital selective calling (DSC) transmitted on: (i) VHF channel 70, or (ii) MF/HF on the frequencies 2187.5 kHz, 8414.5 kHz, 4207.5 kHz, 6312 kHz, 12577 kHz or 16804.5 kHz; (m) a ship-to-shore distress alert transmitted by the ship’s Inmarsat or other mobile satellite service provider ship earth station; (n) signals transmitted by emergency position-indicating radio beacons; (o) approved signals transmitted by radiocommunication systems, including survival craft radar transponders.

2: Misuse prohibited

The use or exhibition of any of the foregoing signals except to indicate distress and need of assistance is prohibited, as is the use of any signal that may be confused with them.

3: Other relevant signals

Attention is drawn to the relevant sections of the International Code of Signals, the International Aeronautical and Maritime Search and Rescue Manual, Volume III, and the following signals: (a) a piece of orange-coloured canvas with either a black square and circle or other appropriate symbol (for identification from the air); (b) a dye marker.

A training aid, not the official text. The COLREGs are an IMO convention, and your national authority publishes the version that applies in its waters. Check the rules themselves before you rely on them at sea. Download the rules.