The International Cospas-Sarsat Program, a program that uses a satellite constellation to relay distress alerts to search and rescue authorities, terminated satellite processing of distress signals from 121.5/243 MHz EPIRBs (Emergency Position Indicating Radio Beacons) on Feb. 1, 2009. Mariners, aviators, and individuals using emergency beacons will need to switch to those operating at 406 MHz if they want to be detected by satellites.