Distress signals

A distress signal communicates distress with need of assistance. It differs from a light making a vessel visible or a manoeuvring warning. Rule 37 refers to the signals in Annex IV, giving them normative identity without teaching radio, pyrotechnic or beacon operation. The drawing presents message families rather than buttons, operating frequencies, firing methods or activation sequences. Recognition education and operational preparation remain distinct. A person can learn why a signal has a particular meaning without that lesson establishing competence to produce or respond to it in an actual emergency.

Annex IV paragraph 1 identifies signals that indicate distress and need of assistance when used together or separately. They include continuous sounding of a fog-signalling appliance, Morse SOS, radiotelephony Mayday, International Code signal N.C., and a square flag with a ball above or below. Specified visual and pyrotechnic signals, electronic alerts and approved radiocommunication signals are also included. These are identities with their own conditions; the list need not become an execution exercise for its meaning to be understood. Recognition does not select equipment or an appropriate operational method.