The case for AIS

Trampers heading out into the back country usually carry a personal locator beacon (PLB). An EPIRB (Emergency Position Indicator Radio Beacon) uses the same technology and no boatie should head out without one. In both cases, activating the beacon transmits a distress signal – together with its precise GPS coordinates – to an overhead satellite network.

There are even compact waterproof locator beacons for kayakers and swimmers, and with a suitable housing some PLBs can also be taken underwater by scuba divers. The locator beacon technology is reliable, compact and very precise. Unfortunately, the strong point of the technology is also its greatest weakness – it’s based on a satellite signal.

This means beacons can be used in remote locations with zero radio or mobile phone signal. But it also means the alert has to be passed through the global satellite response system,