What frequencies do EPIRBs transmit on?

The correct frequencies for Emergency Position Indicating Radio Beacons (EPIRBs) are 406 MHz and 121.5 MHz. The 406 MHz frequency is utilized for the primary signal, which provides a digital location that helps search and rescue operations identify the distress signal with accuracy. The 121.5 MHz frequency functions as a secondary signal, often referred to as an "old" distress frequency, which was used in earlier models of EPIRBs and is still monitored by aircraft and marine rescue services.

The choice of 406 MHz for modern EPIRBs is particularly beneficial because it allows for longer transmission ranges and more precise tracking information through satellite systems, enhancing the chances of a successful rescue. The inclusion of 121.5 MHz serves as a backup, ensuring coordination and response capabilities with older systems that may still be in use.

The other frequencies listed in the incorrect choices, such as 243 MHz and 455 MHz, do not align with the standard operational protocols established for EPIRBs used in maritime distress signaling. For instance, 243 MHz is reserved for military distress signaling, while 455 MHz is not typically associated with maritime distress communication at all. Thus, the correct frequencies for EPIRBs, which enable effective search and rescue