What is one purpose of the 121.5 MHz signal in EPIRBs?

The purpose of the 121.5 MHz signal in Emergency Position Indicating Radio Beacons (EPIRBs) is primarily to assist Search and Rescue (SAR) units in locating the EPIRB. This frequency is a secondary emergency frequency that is monitored by search and rescue agencies, allowing them to pinpoint the location of the distress signal when activated.

The 121.5 MHz signal can be detected by aircraft and other search and rescue assets, facilitating a quicker response in emergencies. When the signal is transmitted, it helps narrow down the search area, thereby enhancing the efficiency of rescue operations.

In contrast, while the distress information and alerts to other vessels can be associated with EPIRB functions, the specific role of the 121.5 MHz signal is focused on aiding SAR teams in the location of the distress situation. Similarly, providing weather updates is not a function of EPIRBs, which are strictly geared towards emergency distress signaling.