Personal locator beacon (PLB)

A PLB (Personal Locator Beacon) is a device about the size of a phone that, when activated, sends a distress signal on 406 MHz by satellite (the international Cospas-Sarsat system) with your identifier and your GPS position. It works where there is no cell signal, requires no subscription, and is received by U.S. rescue centers.

• Register it (required and free) with NOAA at beaconregistration.noaa.gov (or at 888-212-7283), with your details and emergency contacts. Registration lets rescuers know who you are and call your contacts to confirm whether it's a real emergency. NOAA will ask you to verify your information every 2 years, and you must update it if you change phones or sell the beacon.
• Use it only in grave and imminent danger, when you can't call for help any other way.

• To activate it: fully extend the antenna, hold it with the antenna vertical and a clear view of the sky (not under a roof, inside a car, or covered by your body), and leave it on until rescue arrives. Don't switch it off "to see if it worked."
• If you activate it by mistake, turn it off and notify the authorities immediately, following the manufacturer's instructions and NOAA's registry instructions.
• Difference from satellite communicators: these (with a monthly fee) let you send and receive text messages, which helps rescue a great deal; the PLB only sends the alert, but its signal is that of the official system and its battery lasts years in storage. Check the battery's expiration date.