Emergency Position-Indicating Radio Beacon (EPIRB)

A registered maritime distress beacon that transmits a 406 MHz alert for detection through the Cospas-Sarsat satellite system.

Usually abbreviated EPIRB, it sends a digitally coded identity and may transmit encoded position from an internal or connected navigation receiver. The alert is routed through the international system to the appropriate rescue coordination authorities; a separate 121.5 MHz homing signal, AIS locating signal or visible light may also be provided by the model.

EPIRBs can be manually activated and some installations have float-free housings designed for automatic release and activation. Registration, mounting, battery and hydrostatic-release expiry, self-tests and model-specific operating instructions are essential; accidental activation must be reported rather than silenced without notification.