What to Do If You Hear a MAYDAY on VHF Radio

Sending a Mayday is well rehearsed in every VHF course — but what about the other side of the radio? Here is exactly what to do when you are the one who hears a distress call: how to listen and log it, when to answer, how to relay it, and what the law expects of you.

The first seconds — listen and log

A Mayday almost always comes without warning, on Channel 16 (or as a DSC alert that sends you there). The instinctive urge is to grab the mic and answer. Resist it for a moment. The two most useful things you can do in the first seconds are simple:

• Stop transmitting. Do not key up on Channel 16 for anything routine — you may talk over the distress.
• Listen and write. A distress message is dense with information that rescuers need. You are now a witness; capture it.

Note the time immediately — it matters for the rescue coordination and for your log.

What to write down

Keep a pad by the radio. As you listen, capture as much of this as you can — you may be the clearest receiver of a weak or panicked transmission:

Who should answer the Mayday?

In most sea areas a coastguard or coast radio station (CRS) is listening on Channel 16 and DSC, and is by far the best placed to take charge — they can task lifeboats, helicopters and nearby shipping. So when you hear a Mayday, give them time to acknowledge first.

Answer yourself when:

• No coast station or coastguard acknowledges the Mayday after about five minutes — the standard RYA / GMDSS guidance is to wait roughly five minutes before you step in — and
• You received the call and can either assist or relay it onward.

How to acknowledge a Mayday

If you do answer, keep it short and use the proper format. You are confirming you heard it:

Then, if you can, contact the coastguard and pass on everything you logged. If you are close and able to help, tell them your position, speed and ETA so they can coordinate.

Sending a MAYDAY RELAY

A MAYDAY RELAY is how you raise the alarm on behalf of someone else. Use it when:

• You see or hear of a vessel in distress that cannot transmit herself (no working radio, or you witness an incident); or
• You have heard a Mayday that no coast station has acknowledged, and you fear the authorities have not received it.

Radio silence — the SEELONCE words

Distress traffic must not be interrupted, so the COLREG/GMDSS radio procedure uses a set of French-derived phrases to control the frequency. You should recognise them and obey them:

If you hear SEELONCE MAYDAY, stay off the frequency entirely unless you are part of the distress traffic.

If it arrives as a DSC distress alert

On a DSC-equipped set, a distress alert may come first as an alarm and an on-screen alert before any voice call. Handle it like this:

Your duty to assist

Hearing a distress is not a spectator event. Under long-standing international maritime law — the SOLAS Convention and the master's duty — a vessel that learns others are in distress at sea must proceed with all speed to their assistance, so far as she can without serious danger to her own vessel, crew or passengers.

That qualification matters: you are not asked to throw your own people into grave danger. But you cannot ignore a distress you are genuinely able to help with. If you are close and capable, make your presence and intentions known to the coordinating coastguard.

What if it's a PAN-PAN, not a Mayday?

Not every call is a Mayday. PAN-PAN (spoken three times) is the urgency signal — a serious situation concerning the safety of a vessel or person, but not grave and imminent danger to life. A broken-down engine drifting toward a lee shore, a minor injury needing advice, a person overboard who has been recovered. Listen, log, and keep clear, exactly as with a Mayday — but understand the priority is one level down. SÉCURITÉ (the safety signal) carries navigational or weather warnings; note these too.

Practise distress procedures before you need them

The reason a Mayday at 0300 in fog turns out well is rehearsal. SkipperCheck's online VHF/SRC course drills the full set of distress, urgency and routine procedures — sending and receiving — on a realistic VHF/DSC simulator, so the words and the sequence are muscle memory long before you ever need them.

Frequently asked questions

What should I do if I hear a MAYDAY on the radio?

Stop transmitting and listen. Note the time and write down the vessel's name, position, nature of distress, number of people on board and assistance required. Let a coastguard answer first; if no one does and you can help or relay, acknowledge on Channel 16 ("RECEIVED MAYDAY"), pass the details to the coastguard, and send a MAYDAY RELAY if the alarm hasn't reached the authorities. Keep Channel 16 clear.

Should I answer a MAYDAY immediately?

No — give the shore stations time first. A coastguard or coast radio station is best placed to coordinate the rescue and will normally acknowledge. The standard RYA/GMDSS guidance is to wait about five minutes; answer yourself only if no shore station responds in that time and you are able to assist or to relay the call.

What is the difference between MAYDAY and MAYDAY RELAY?

MAYDAY means your own vessel is in grave and imminent danger. MAYDAY RELAY means you are transmitting a distress on behalf of another vessel — for example one that cannot transmit, or whose Mayday you heard but no one acknowledged. The word "RELAY" identifies you as the messenger, not the casualty.

What does SEELONCE MAYDAY mean and what should I do?

SEELONCE MAYDAY imposes radio silence on the distress frequency so distress traffic is not interrupted. It is used by the vessel in distress or the station controlling the incident. If you hear it, stay off the frequency unless you are part of the distress traffic. SEELONCE FEENEE signals that the distress is over and normal working may resume.

Should I acknowledge a DSC distress alert?

Not by DSC. Silence the alarm, switch to Channel 16 and listen — a coastguard should acknowledge by DSC, and a ship doing so can prevent the alert reaching the authorities. If no coast station responds after about five minutes and you can help, acknowledge by voice on Channel 16 and contact the coastguard by voice. On VHF you do not send a DSC distress relay.

Am I legally required to help a vessel in distress?

Yes — international maritime law (SOLAS and the master's duty) requires a vessel that learns of others in distress to proceed to their assistance so far as she can without serious danger to herself, her crew or her passengers. You are not obliged to endanger your own people, but you cannot ignore a distress you are able to help with.

Related reading

• How to Send a MAYDAY Distress Call on Marine VHF Radio — the other side: sending one yourself
• Short Range Certificate (SRC) — Complete Guide — the marine VHF qualification
• Free sailing video lessons — VHF, COLREG, distress signals and more
• Maritime glossary — VHF, COLREG and navigation terms