The term "406 MHz" refers to a specific frequency used for emergency distress beacons, particularly in aviation and maritime contexts. These beacons transmit signals to satellites, allowing for rapid location and rescue of individuals in distress. The 406 MHz frequency is part of the COSPAS-SARSAT satellite system, which is designed to assist in search and rescue operations worldwide. 406 MHz beacons are more effective than older 121.5 MHz beacons, as they provide accurate location data and are monitored continuously by satellites. When activated, these beacons send a unique identifier, enabling rescue teams to quickly identify the source of the distress signal and respond accordingly.