Personal Locator Beacons (PLBs) are the last resort in emergencies, on land but especially at sea. They are typically small, handheld, subscription-free devices with the sole purpose of sending out an emergency SOS signal to nearby rescue centres. Their signals are picked up by specialist search and rescue COSPAS-SARSAT satellites and they operate on strict frequencies so as not to interfere with other radio waves. PLBs can be used anywhere, and can be paired with other satellite communication devices like satellite phones or trackers for optimum accuracy and location precision.

The Military

Some PLBs are designed with military-grade ruggedness and so can be used in even the most extreme environments. They can be activated on impact so the user doesn’t have to worry about consciously sending an alert while in a stressful situation. They are lightweight and compact enough to be strapped to a bulletproof vest for example.

The Search

To maximise the chances of a successful rescue, some PLBs operate on the 406MHz frequency band. This works across both marine and land environments, and the PLB’s signals are received by the COSPAS-SARSAT satellites, the international satellite system for search and rescue.

Other PLBs, like the new Ocean Signal PLB3 use AIS (Automatic Identification System) which is an automated tracking system that displays other vessels in the vicinity. It is a broadcast transponder system that operates in the VHF mobile maritime band.


Personal Locator Beacons like the new PLB3 employ some of the latest and more advanced technological features like Near Field Communication (NFC) and AIS in order to truly maximise the chances of a successful rescue. Developments like this make use of the technology sector’s tried and tested assets in innovative ways in the name of human safety.

The Rescue

When a PLB is activated, the help or assistance can come from rescue authorities, colleagues, friends or nearby monitoring assets, depending on the type of PLB and the receiving equipment used. When a distress signal is received and identified to be an emergency call from a specific area, the relevant and nearby Rescue Coordination Centre (RCC) in that area is alerted. With PLBs that operate on frequencies 406MHz and 121.5MHz, the 121.5MHz band is used to locate the individual in distress once a rescue asset is in close proximity.

What You Need to Know About Activating a PLB

PLB activations are taken very seriously, with emergency call-outs costing a lot of time and money, which is why emergency distress calls should only be used as a last resort and in life-or-death situations. The beacons themselves are designed to make distress calls easy, but their activation buttons are often located behind plastic casing that the user must flip up. Distress signals are designed so that they can’t be made by accident.

As always, our team of experts is here to help. So, if you need any advice about our range of Personal Locator Beacons, contact us via:

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