A Personal Locator Beacon (PLB), supporting two operation modes local monitoring and remote monitoring. The apparatus includes a PLB that supports the present operation mode, as well as a local monitoring mode, employing the same transmitter, and automatically switching between modes. Upon activation, the PLB first tries to communicate with a local monitoring station, at a low transmission power, and at a high repetition rate, in purpose of dealing with the PLB call locally, without involving the remote monitoring station. Then, if not acknowledged by a local monitoring station, the PLB increases its transmission power, enabling access to a remote monitoring station. In a preferred embodiment, the PLB is carried by a person onboard a vessel, to alarm upon a Man Overboard (MOB) accident, the local monitoring station is installed onboard the same vessel, and the remote monitoring station is part of a satellite Search and Rescue (SAR) system, as Cospas-Sarsat.