Emergency radio beacons (ERB) are used in COSPAS-SARSAT system for transmission of emergency signals and for position finding of those in distress by search and rescue services.

Three radio beacon types are supported: aviation (ELT), maritime (EPIRB) and personal (PLB).

In case of an emergency, ERB is activated automatically or manually depending on the model. After activation, they transmit a radio dispatch with 5 W power. The dispatch contains the following digital information: registration country data, radio beacon id number, emergency type message and, if a model with a navigation receiver is used, calculated geographic coordinates.

Because 406 MHz frequency is monitored by both geostationary and low Earth orbit satellites, radio signals are detected quickly, permitting immediate start of search and rescue missions.

Emergency message delivery time to rescue services when using new generation ARB-406 radio beacons doesn't exceed 5 minutes even in extremely unfavorable weather and geographic conditions.

Previously, 121.5 MHz and 243 MHz frequencies were supported by the system, too, but the technology was judged outdated and since 2009 these frequencies are no longer used within COSPAS-SARSAT system.

Emergency radio beacons are a national search and rescue infrastructure component in numerous countries and are mandatory to be installed on sea vessels and aircafts.