A system of communication using coloured flags flown from a vessel's mast or signal halyard, each representing a letter of the alphabet, a numeral, or a specific meaning. The International Code of Signals (ICS) standardises flag signal meanings, with single-flag signals conveying urgent or common messages.
Category: Maritime Communication
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DSCDigital Selective Calling, a semi-automated method of establishing a radio call using digital codes transmitted on VHF, MF, and HF radio frequencies.LRITLong Range Identification and Tracking, an international system for tracking vessels globally, adopted by the IMO as an amendment to SOLAS.MaydayThe internationally recognised voice radio distress signal, spoken three times at the beginning of a radio distress call to indicate that a vessel, aircraft, or person is in grave and imminent danger and requires immediate assistance.NAVTEXNavigational Telex, an international automated medium-frequency direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent maritime safety information to ships.Pan-PanAn internationally recognised urgency signal, spoken three times at the beginning of a radio message, indicating that there is an urgent situation on board a vessel but no immediate danger to life or the vessel.SARSearch and Rescue, the coordinated effort to locate and recover persons in distress at sea, involving maritime rescue coordination centres (MRCCs), coast guard units, naval vessels, and commercial ships.
Back to DictionaryEntry updated May 2026