Satellite Emergency Beacons for Remote Expeditions: PLBs, EPIRBs and Satellite Messengers

13 November 2026

A 406 MHz beacon is only as useful as the information attached to it. The Maritime and Coastguard Agency (MCA) says these devices send a distress signal via satellites to alert search and rescue authorities to your location, and it is equally plain that you must register your beacon and keep that registration up to date. For anyone heading for open water, high latitudes or empty hill country, that second duty is easy to overlook while the kit list grows. It should not be. An unregistered beacon can still raise an alarm, but the people responding have far less to go on.

What a 406 MHz beacon is and how it works

GOV.UK's guidance on 406 MHz beacons describes three types. EPIRBs are for ships, ELTs are for aircraft, and PLBs are for personal use. All three work on the same principle: when activated, the beacon transmits a distress signal that is picked up by satellites and passed to search and rescue authorities, together with your position.

The RNLI describes the personal version in plain terms. A PLB uses search and rescue satellites to send a message to the Coastguard, which then sends search and rescue assets to the GPS position given by the PLB. The chain is short. You press the button, the satellites relay the alert, the Coastguard receives it, and a response is launched to the coordinates the beacon has reported.

What turns that alert into a useful one is the registration record. Each beacon carries a unique identifier, known as the HEX ID or UIN. When the signal arrives, the authorities can match it to the details held against that beacon: who owns it, what it is attached to, and who to call. For a vessel, that can mean the difference between a vague alarm and a quick confirmation that a named boat with a known number of people aboard is in trouble. For an individual, it means a 24-hour contact who can say whether you are meant to be where the beacon says you are.

This is also why the three categories matter. The device is built for a particular kind of user, and the registration details differ accordingly. A ship's beacon is tied to the ship, while a personal beacon is tied to a person. Buying the wrong type, or registering it as though it were another, defeats much of the point.

UK registration rules for EPIRBs and PLBs

The MCA's UK Beacon Registry lets users register a UK 406 MHz beacon online. Before you start, the registry asks you to have to hand the beacon's HEX ID or UIN, the manufacturer's serial number, the model, and an emergency contact for search and rescue authorities. Gather those from the beacon's label and its packaging before you open the form, because the identifier is printed on the device and is easy to misread in a hurry. If you are registering for a vessel, the registry also asks for the vessel's name, number, call sign and MMSI number, plus details of its radio communications equipment.

The detailed requirements sit in the MCA's MSN 1924, on MF EPIRB and PLB registration. For an EPIRB, it calls for the ship name, MMSI, radio call sign, EPIRB serial number and identifiers, beacon owner details, up to three 24-hour emergency contacts, and a ship description with survival-craft information. For a PLB, it requires the owner's name, address, telephone number and email, the PLB serial number and identifiers, the HEX ID, and up to three alternative 24-hour emergency contacts.

Those emergency contacts deserve more thought than they usually get. The MSN specifies 24-hour contacts, which means people who can actually be reached at three in the morning, not just someone who will see an email on Monday. On an expedition, choose people who know your route, your intended timings and your party, and tell them before you leave that their name is on the record. A contact who is surprised by a call from the Coastguard is a contact who loses minutes.

Scope is the part most likely to cause confusion. In March 2026 the MCA said that registration of all current and new PLBs carried on board a UK flagged vessel, hovercraft or mechanically propelled watercraft is required online and at no cost. In the same announcement, published on GOV.UK, the MCA said the requirement does not apply to unpowered craft such as paddleboards, kayaks and canoes. It still encourages all PLBs to be registered. So a paddler is not bound by the new rule, but the sensible course is to register anyway, since an unregistered beacon gives responders the least information at the moment they need the most.

Two practical points follow. Registration is free, so there is no reason to pay anyone to do it for you. And "current" PLBs are covered as well as new ones, so a beacon bought years ago and kept in a grab bag falls within the requirement if it is carried on a qualifying craft. If you bought a beacon second-hand or inherited one from a friend, the details attached to it may be out of date or belong to someone else, and they need updating.

Choosing between a PLB, an EPIRB and a satellite messenger

Not every device that can call for help is a 406 MHz beacon. Satellite messengers such as Garmin's inReach range work differently, and Garmin's own support guidance makes the distinction explicit. It says inReach satellite communicator devices do not have a HEX ID or UIN, do not send a radio transmission when SOS is triggered, and do not need to be registered with maritime agencies for SOS. That is a different arrangement from a beacon, and it affects both how you plan and what paperwork you do.

The table below sets out how the three compare.

The choice follows from what you are doing. An EPIRB belongs to a vessel and is registered against it, so it is a matter for the skipper or owner and for the boat's safety planning. A PLB goes with the person, which is why it suits someone moving between environments, from a boat to a shore party to a hillside, and why its registration is built around the owner's name, address and contacts.

A satellite messenger sits outside the beacon system. Because Garmin states that it carries no HEX ID or UIN, there is nothing to enter in the UK Beacon Registry for it, and you should not expect it to appear there. Do not assume, though, that skipping registration for the messenger frees you from registering a beacon you also carry. If you take both, the beacon still needs its own record, and its emergency contacts still need to be current. The two devices are separate tools with separate rules, and mixing them up on the paperwork side is an easy mistake to make.

Licensing, carriage and practical UK compliance points

Registering a beacon is one obligation. Radio licensing and carriage rules are another, and in aviation they are handled separately. Ofcom's aeronautical licence products page lists emergency locator transmitters operating on 121.5 and 406 MHz as required aircraft equipment types. That is the aircraft counterpart to the maritime devices above: the ELT is the third category GOV.UK names alongside EPIRBs and PLBs. For anyone flying into a remote start point, whether as owner or charterer, the aircraft's equipment is a matter for the licence and the operator, and it does not replace a personal beacon carried by individuals on the ground.

The practical lesson for expedition planners is to keep the layers apart. A vessel carries an EPIRB registered to the vessel. A person may carry a PLB registered to them. An aircraft carries an ELT under its own licensing arrangements. A satellite messenger, if you have one, falls under neither registration regime for SOS purposes, according to its maker. Each device answers to a different record, and a single tick-box exercise will not cover them all.

Before departure, a short routine saves trouble. Check that every beacon in the party has a registration and that the HEX ID on the record matches the one printed on the unit. Confirm that your emergency contacts are reachable and that they know your plans. Update the record whenever the beacon changes hands, the vessel changes name or the contact details change, because the MCA's instruction is to keep the registration up to date, not merely to create it once. If you are borrowing a beacon for a trip, update the owner and contact details for the duration or arrange for the owner to do so.

The newest development is the one to act on now. Since the MCA's March 2026 announcement, registration of PLBs carried on UK flagged vessels, hovercraft and mechanically propelled watercraft is required, online and free. Set aside a quarter of an hour, have the serial number, model and HEX ID in front of you, and do it before you next go afloat.