Key takeaways
- A PLB sends a one-way emergency distress signal with your GPS location to rescue authorities via satellite.
- It uses the government Cospas-Sarsat network on 406 MHz — no subscription required.
- It's a dedicated SOS device: powerful and reliable, but it only signals an emergency (no messaging).
- Differs from satellite messengers, which add two-way texting and tracking but need a subscription.
Personal Locator Beacon.
What a PLB is
A PLB (personal locator beacon) is a compact emergency device that, when activated, transmits a distress signal with your GPS coordinates to search-and-rescue authorities. It works through the government-run Cospas-Sarsat satellite network on the powerful 406 MHz frequency — the same system used by aircraft and ships — making it a reliable last-resort way to summon rescue from the remote backcountry.
How it works
You activate a PLB only in a genuine life-threatening emergency. It broadcasts your registered identity and location; the satellite network relays it to rescue coordination authorities, who dispatch help. There’s no subscription — you just register the device (free and required) with your national authority.
After a serious fall leaves a solo hiker unable to walk and out of cell range, they deploy their PLB; the 406 MHz signal and GPS location reach rescue authorities, who launch a search to their exact coordinates.
PLB vs satellite messenger
A PLB is a dedicated, subscription-free SOS device — but it only signals an emergency, with no messaging. A satellite messenger adds two-way texting, tracking, and check-ins for a subscription fee. See PLB vs satellite messenger. Either belongs with your Ten Essentials for remote travel.
The bottom line
A PLB is the no-frills, no-subscription emergency beacon: press it in a true crisis and a powerful 406 MHz signal with your location goes straight to rescue authorities. It does one thing supremely well — summon help — so if you want two-way messaging, tracking, and check-ins, look at a satellite messenger instead.
Frequently asked questions
What is a PLB?
A PLB, or personal locator beacon, is an emergency device that broadcasts a distress signal containing your GPS location to search-and-rescue authorities via the government Cospas-Sarsat satellite system. You activate it only in a genuine life-threatening emergency; it has no monthly fee and is built to summon rescue when nothing else can.
How is a PLB different from a satellite messenger?
A PLB is a one-way SOS device on the powerful 406 MHz frequency with no subscription, dedicated solely to emergencies. A satellite messenger (like a Garmin inReach or SPOT) adds two-way text messaging, tracking, and check-ins but requires a paid subscription and uses commercial satellite networks. See our PLB vs satellite messenger comparison.
Do PLBs require a subscription?
No. PLBs work on the free, government-run Cospas-Sarsat system, so there's no subscription — you just register the device (which is required and free) with your national authority. This makes them simple and cheap to own long-term, at the cost of having no messaging or non-emergency features.
Sources
- Beacons & Cospas-Sarsat — NOAA
- Backcountry emergency communication — The Mountaineers