Distress, Urgency and Safety Communications Procedures
What this domain tests
The Distress, Urgency and Safety Communications Procedures domain asks you to choose the correct priority, message format and frequency for an emergency, and to control or relay traffic without interfering with other stations. Most missed questions come down to one decision: is there grave and imminent danger right now, or only a safety concern?
The three priority signals
- MAYDAY (three times) - distress: a ship, aircraft or person is threatened by grave and imminent danger and needs immediate assistance. It pre-empts all other traffic.
- PAN PAN (three times, "pahn-pahn") - urgency: a matter concerning the safety of a ship or person that does not yet require immediate assistance, such as a serious but stable medical case needing advice, or a machinery failure in heavy weather.
- SECURITE (three times, "say-cure-e-tay") - safety: navigational or meteorological warnings and other important safety information.
Distress message content
MAYDAY x3, THIS IS, ship name / call sign / MMSI x3, MAYDAY, position (latitude and longitude, or bearing and distance), nature of distress, assistance required, persons on board, any other useful information (hull type, cargo, hazardous goods), OVER. The alerting routes are VHF Ch 16 (156.8 MHz), 2182 kHz, HF radiotelephony (4125, 6215, 8291, 12290, 16420 kHz), DSC and NBDP, and satellite.
Controlling and relaying
Distress traffic is controlled by the station in distress or by the coast station or RCC that takes charge, which imposes silence with SEELONCE MAYDAY. When the emergency ends the controller sends SEELONCE FEENEE; under urgency, PRUDONCE restricts working. A station may send MAYDAY RELAY when it learns of a distress from a station that cannot transmit itself, or when a confirmed alert remains unacknowledged, and must never impersonate the casualty.
Worked example
You are 400 nm off Bermuda in an A3 vessel; a crew member has severe abdominal pain but is conscious and stable, and you want medical advice by radiotelephone. Reasoning: nobody yet faces grave and imminent danger, so this is urgency, not distress. Send a DSC urgency call to a coast station, move to the proposed working frequency (for example 8291 kHz), then: PAN PAN x3, THIS IS, name and call sign x3, position, "request medical advice", persons on board, OVER. If the patient deteriorates, upgrade to MAYDAY.
Traps
Calling MAYDAY for a non-imminent problem; using Ch 70 for voice (prohibited); omitting OVER or reading the whole message without letting the other station reply; relaying a distress on your own initiative after the alert has been acknowledged; forgetting that after a Ch 70 alert you follow on Ch 16 with the voice distress call and message.