EPIRB (Emergency Position Indicating Radio Beacons) systems require GNSS location data. EPIRB is used to alert search and rescue services in the event of an emergency by transmitting a coded message on the 406 MHz distress frequency via satellite and earth stations to the nearest rescue co-ordination centre.
Some EPIRBs also have built-in GPS enabling rescue services to accurately locate a vessel to +/- 50 metres. EPIRBs are generally installed on boats and can either be operated automatically after an incident or manually. In most countries EPIRBs are mandated to be used in all commercial shipping including on yachts and leisure boats.