Personal Locator Beacons or PLBs are portable units that operate much the same as EPIRBs or ELTs. These beacons are designed to be carried by an individual person instead of on a boat or aircraft. Unlike ELTs and some EPIRBs, they can only be activated manually and operate exclusively on 406 MHz. And like EPIRBs and ELTs all PLBs also have a built-in, low-power homing beacon that transmits on 121.5 MHz. This allows rescue forces to home in on a beacon once the 406 MHz satellite system has gotten them "in the ballpark" (about 2-3 miles). Some newer PLBs like the ACR AquaFix also allow GPS units to be integrated into the distress signal. This GPS-encoded position dramatically improves the location accuracy down to the 100-meter level…that’s roughly the size of a football field!
In the United States, PLBs are now authorized for nationwide use. This authorization was granted by the FCC beginning July 1st, 2003.
Prior to this, only residents of Alaska had been able to use PLBs. The Alaska PLB Program was set up to test the capabilities of PLBs and their potential impact on SAR resources. Since March of 1995, the experiment proved very successful and helped save nearly 400 lives while generating only a few false alerts. The success of the Alaska PLB program undoubtedly paved the way for nationwide usage of these devices.