Personal locator beacon (PLB): how it works, registration, activation

The PLB transmits on an internationally designated distress frequency to satellites of the Cospas-Sarsat system. This system was set up by several states in the 1980s and is operated internationally. It receives signals from maritime, aviation and personal beacons. Ground stations pick up the signals and pass the alert to a rescue coordination centre, which then organises a search.

The signal contains a unique identifier that points to the registration data: who owns the device, whom to contact in an emergency, sometimes details of the planned trip. That lets rescuers make enquiries and rule out false alarms more easily. Most PLBs also determine their position via satellite navigation (GNSS) and send it along, which narrows the search considerably.

Many beacons also send a weaker homing signal. With it, rescue teams nearby – for example in a helicopter – can pinpoint the beacon over the last stretch. How quickly an alert arrives and how accurate the position is depends on many factors; this entry deliberately gives no figures on that.

Register the beacon with the responsible national authority and keep the contact details up to date. Without registration, rescuers do not know whom to ask and may lose valuable time. Some authorities let you store details of the planned trip. Registration requirements, responsible authorities and permitted device types differ by country – check local rules, including when travelling abroad.

Read the instructions calmly at home. Run the self-test only as the manufacturer describes – a wrong 'test' can trigger a real alert. Check the battery and expiry dates before every trip. The battery is usually not user-replaceable and must be changed by a dealer or the manufacturer.

Carry the PLB on your body, for example on a vest or shoulder strap, not in your pack. In a fall, a capsize or an avalanche the pack can be lost – and the beacon with it.

A PLB is intended for grave and imminent danger. If you can make a call, dial the local emergency number first (112 in the EU) – on the phone you can describe what is going on. If that is not possible, deploy the antenna as instructed, activate the beacon and hold it with a clear view of the sky, or place it that way. Do not cover the antenna with your body, and if possible do not put it in a narrow rock crevice or under dense trees.

A common mistake: switching the device off because nothing seems to happen. A PLB usually gives no feedback on whether the alert has arrived. Leave it switched on until you are rescued anyway, because rescuers use the signal to locate you. Stay in one place if possible and also use visual and sound signals: whistle, mirror, lamp, coloured cloth.

A PLB is not for non-life-threatening problems, for example when you are running late or are no longer sure of the way but are unhurt and sheltered. Every alert sets a search in motion that ties up people and equipment. False alarms can lead to costs or penalties in many countries.

If the beacon is activated accidentally, switch it off and immediately inform the responsible rescue coordination centre or registration authority so that no search is started. That is no reason to feel ashamed – what matters is that you report it. Store the beacon so the trigger cannot be pressed by accident, for example between hard objects in a pack.

A PLB has advantages: it works worldwide without a mobile network, usually needs no subscription and is built rugged for emergencies. Its drawback: it is one-way. You can only raise the alarm, not describe what happened, and you do not find out whether help is on its way.

Satellite messengers, on the other hand, usually allow two-way messages but need a subscription and a charged battery. Which solution fits depends on destination, budget and the wish to communicate; some people carry both. On vessels, similar beacons are called EPIRBs, in aircraft ELTs. They use the same satellite system but are registered to the vessel or aircraft.