A PLB is the most reliable GPS emergency signalling device; also called EPIRB (Emergency Position-Indicating Radio Beacon) these tracking transmitters aid in the detection and location of people in distress. They interact with the international satellite system for search and rescue (Cospas-Sarsat); when activated, they send out a distress signal that is monitored worldwide and the location of the distress is detected by satellites. The purpose of a distress radiobeacon is to help rescuers find survivors within the first 24 hours following an emergency.
We will be carrying a ACR ResQ Link PLB
A SPOT won't work if you don't pay the annual membership. It is like having a fire extinguisher that will work only if you paid your bills. And because a SPOT is designed to be used for daily tracking the batteries might run out. A PLB is more expensive in the short run, but it is a simple device designed for emergencies and used by boats, military personnel and SAR.