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What is a PLB (personal locator beacon) and how does it work?

Updated: Nov 18, 2022

PLB stands for 'Personal Locator Beacon' and is used as in an emergency when in remote areas such as the mountains or out at sea. It is important to start out with some sound advice. The use of PLB's and other emergency devices, and the presence of rescue services and their associated bodies, are there as a back up for unforeseen circumstances that may arise that are life threatening, and should not be seen as a reason to take unnecessary risks, or be a substitute for good planning and smart decision making. Alot of your local rescue services such as the Mountain Rescue and Lifeboat service are crewed by volunteers who drop everything in an emergency, and give up a lot of their free time to be trained to such a high level.

To begin, PLB's come in all shapes and sizes but some of the smallest ones easily fit into the palm of your hand. Their batteries have a varied lifespan, this one is approx 7 years.

When should I activate my PLB?

It's important to remember that a PLB is a last resort, only to be turned on in life-threatening situations, when no other direct communication is available.

How does a PLB work?

When you set of the emergency signal, the truth is not a lot happens, no great loud alarm or siren, bright flashing lights and fireworks, maybe a simple tiny L.E.D. that reminds you you have activated your PLB and that word is getting out. It can be a very anxious & lonely time waiting for help, with you fingers crossed hoping rescue is on the way.

The process looks a bit like this:

Step 1: Trigger the emergency signal on your PLB

Step 2: That signal is received by one of the many satellites connected to the International Cospas-Sarsat Programme. (An international initiative which is intergovernmental, non-profit and treaty based, which is dedicated to detecting and locating emergency beacons such as PLB's that have been activated by people, aircraft or vessels in distress)

Step 3: This signal is collected by a land based control centre before being forwarded on to your nearest Rescue Coordination Centre, relative to your location.

- Somewhere in this mix they will try to reach out to your contact to clarify if this is a genuine emergency and not an accidental trigger.

Step 4: The appropriate rescue team is dispatched to the location of you emergency signal.

How to register your PLB

When you purchase your PLB you will need to register it one of the following ways below before relying on it in an emergency. Any one PLB can work anywhere in the world not just the country you purchased it in. It may be worth your time to see if local registration is required, or whether you need to update your details if and when you move residence etc.

ONLINE at the The UK Beacon Registry official site (uk purchased beacons only)


Direct via Email / Fax (All Beacons, & Beacons purchased overseas)

Telephone: +44 (0)20 3817 2006

Fax: +44 (0)1326 319264

Monday to Friday, 9am to 5pm (except public holidays)

What is the difference between a PLB and an EPIRB?

Normally a PLB is a lot smaller size and weight and is designed to be carried by a single person and specifically registered to the individual rather than to a vessel (boat or ship). An EPIRB (Emergency Position Indication Radio Beacon) should be located on your boat and is registered to the boat.

A PLB has the flexibility to be used anywhere in the world at sea or on land, depending on what frequency they operate on, whereas an EPIRB will only be used at sea.

The down side of a PLB is that due to its size its minimum capacity of transmission of a signal is set to 24 hours, and are not always designed to float in water without the need for some sort of flotation accessory (see below), whereas an EPIRB will transmit for a minimum of 48 hours and are designed to float in the water.

Water triggered PLB's

Some PLB's are designed with built in water sensors and will activates automatically on immersion in water, This means a distress signal can be sent as soon as you hit the water whether you are unconscious or injured or incapacitated in any other way and not able to do so yourself.

Do I need a PLB?

On well known/popular trails, mountain paths, itineraries at sea, or busy rivers where there is likely to be many other individuals or groups passing by and you are unlikely to be without human contact for a day, its fair to say that you probably won't require a PLB. Most emergencies in these situations are solved quicker with a quick dash to high points or line of sight with better signal and you can use your phone.

The process of rescue is not as immediate and can take much longer to get help than when you call 999 or 122 (international emergency number). As you do not have two-way communication there will be a delay in the dispatch of a local rescue team. It is also important you learn how to use your PLB properly, know how to trigger it, how you know you have triggered it, and what is the recommended orientation of the aerial.

Some Useful Emergency Phone Apps

British Red Cross Emergency app


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