Channel 16 VHF (156.8 MHz) is a marine VHF radio frequency used for shipping and maritime purposes, to call up ships and shore stations, and as an international distress frequency.
Channel 16 is used for broadcasting distress calls such as mayday, pan-pan, securité or other urgent safety messages.
Some nations allow the use of marine VHF 16 as an initial calling frequency; after an initial response the call is to be switched to one of the working channels, except in case of emergency traffic.
Authorized usage
VHF channel 16 (156.8 MHz) is monitored 24 hours a day by coast guards around the world. In addition, all sea bound vessels are advised to monitor channel 16 VHF when sailing, except when communicating on other marine channels for legitimate business or operational reasons. Coastguards and others are permitted to broadcast short informative safety messages on channel 16, however, it is an offence in most countries to make false mayday calls. When using the channel to call up ships or shore stations, the call has to be switched to a working channel after the initial response in order to keep channel 16 available to others.