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VHF radio: Channel 16 and the calls that matter

The VHF is the instrument a bridge watch plays all day, and the one instrument where a wrong word costs real time. This module teaches the international radiotelephony procedures in plain English: the three emergency signals, the digital alert behind the red button, the everyday call, and the spelling that keeps a name intact across a noisy channel. Example transmissions are written out line by line, and the standard phrases come with recordings from our SMCP trainer.

Mayday, Pan-Pan, Sécurité: what is the difference?

Mayday: grave and imminent danger, immediate assistance required. Pan-Pan: a very urgent message about the safety of a ship or person, but nobody is in immediate danger of losing their life. Sécurité: a safety message, such as a navigational or weather warning. Each signal is spoken three times at the start of the call, and each has its own card below.

Quiz: 10 questions on VHF procedures → Mayday, Pan-Pan, channels, prowords and the phonetic alphabet.
Where do these procedures come from?

The distress, urgency and safety procedures and the channel plan come from the ITU Radio Regulations. The standard wording comes from the IMO Standard Marine Communication Phrases (SMCP). The equipment and the watches belong to the GMDSS, in Chapter IV of SOLAS. The cards cite the source they draw on.

Distress, urgency and safety

The three spoken signals every watchkeeper must know cold, and the digital alert behind the red button.

Mayday: the distress call Mayday is the spoken distress signal: a ship or person in grave and imminent danger, needing immediate assistance. It outranks every other transmission on the air. Pan-Pan: the urgency call Pan-Pan is the spoken urgency signal: a very urgent message about the safety of a ship or a person, when there is no grave and imminent danger yet. Sécurité: the safety call Sécurité is the spoken safety signal: it introduces a message about the safety of navigation or important weather information. DSC: the red button explained DSC is the digital calling layer of the GMDSS: a short data burst instead of a voice call. On VHF it lives on Channel 70, and its most famous part is the red DISTRESS button.

Everyday radio work

Routine calls, procedure words and spelling that keep you understood the first time.

Routine calls: reaching another station The everyday VHF call: name the station you want, say who you are, agree a working channel and get off the calling channel. Short, slow and predictable is the whole art. Prowords and message markers Prowords are the traffic signs of radio speech: fixed words with fixed meanings, so both sides always know whose turn it is and what kind of sentence is coming. Phonetic alphabet and numbers Alfa to Zulu: the international spelling alphabet used at sea, in the air and by rescue services, plus the seagoing way to say numbers.

The channel and the band

What Channel 16 is for, and what all the other channels do.

Channel 16: the calling and distress channel Channel 16 (156.800 MHz) is the international VHF channel for distress, urgency, safety and calling. Every spoken emergency starts here, and at sea the watch keeps an ear on it. Which channel does what The marine VHF band is cut into numbered channels with assigned jobs. Three are the same everywhere: 16, 70 and 13. Most of the rest depend on where you are.

Procedures per the ITU Radio Regulations, the IMO SMCP and SOLAS Chapter IV. Example ships, call signs and positions are fictional. This is not a legal text: when in doubt, the current wording of the Regulations decides.