When and how to make a distress call

A distress call is the most serious level of emergency. It applies to any situation where a person is threatened by grave and imminent danger and requires immediate assistance.

If you are at sea and use your mobile phone to make a 999 / 112 call, the coastguard is unable to fix your position, so you should always use your VHF radio or DSC (as detailed below).

Making a distress call by voice (VHF radio)

When using your VHF radio to make a distress call you must prefix the call with ‘mayday’ so that we can identify it as a distress call. A distress call has priority over all other transmissions.

A mayday call should be sent on VHF 16 using the following procedure:

1.     check main battery switch is on

2.     switch VHF radio on and select high power

3.     select VHF Channel 16

4.     press and hold down the transmit button and say slowly and distinctly:

Mayday, mayday, mayday

This is *** (speak name of boat three times) Call sign and MMSI number (spoken once)

Mayday *** (speak name of boat once)

My position is *** (latitude and longitude, or true bearing and distance from a known point)

Nature of distress (sinking, on fire etc)

Help required (immediate assistance)

Number of persons aboard

Any other important information (eg drifting, flares, life raft aboard)


5.     On completion of the distress call, release the transmit button and listen. If an acknowledgement is not received, check the VHF set and repeat your distress call.

If you hear a distress call on your VHF radio, write down the details.

If you can help, you should acknowledge accordingly, but only after giving an opportunity for the Coastguard station or some larger vessel to do so.

Making a distress call using DSC

All new VHF radios on sale are now equipped to make and receive DSC (Digital Selective Calling).

If you have a VHF DSC radio aboard you should have an MMSI (Mobile Maritime Service Identity) number. The MMSI number should be interfaced with your GPS (Global Positioning System). You should be familiar with its use and have the necessary licence requirements.

Using the procedures and switches applicable to your particular VHF DSC radio, a DSC Distress alert might be sent as follows:

  • momentarily press the (red, guarded) distress button. The set automatically switches to VHF Channel 70 (DSC distress channel) and transmits a basic distress alert with position and time (from GPS). It then reverts to VHF Channel 16
  • if time permits, select from the DSC menu the nature of the distress (eg fire), then press the distress button for five seconds to send a full distress alert
  • once received, the coastguard sends a distress acknowledgement on VHF Channel 70 before replying on VHF Channel 16. If a distress acknowledgement is not received from the coastguard, the distress alert will be repeated every four minutes

When a DSC Distress acknowledgement has been received, or after about 15 seconds, the vessel in distress should transmit a MAYDAY message by voice on VHF Channel 16, adding its MMSI number to the distress call.

If a distress alert is inadvertently transmitted, an ‘All Stations’ DSC message cancelling the false alert, by date and time, must be sent at once.

Making a 999 / 112 call from shore

If you see a marine incident from the shore, you should dial 999 or 112 and ask for the coastguard.

You will be asked to report on the incident and may need to stay in telephone contact for further communications.