The 406 MHz transmitters send a precise, digitally coded signal that is unique to each transmitter. This provides such information as aircraft type, identification, equipment on boards, and emergency contact phone numbers. Digital coding means that information concerning a 406 transmitter activated anywhere around the globe will be received by search and rescue authorities, typically six hours sooner than with older types of transmitters. Since the inception of the program 13 years ago, more than 4600 lives have been saved. The first satellite was launched by the Soviet Union in 1982, followed by additional Soviet and U.S. satellites.
Today there are six operational U.S. and Russian satellites involved in the program.