Which frequency is commonly used as a backup for distress beacons?

Which frequency is commonly used as a backup for distress beacons?

• A. 121.5 MHz
• B. 156.8 MHz
• C. 243 MHz
• D. 406 MHz

Answer: (D)

The system uses two paths to locate a distress beacon: a satellite-based alert on a dedicated 406 MHz channel and a nearby, ground-based homing signal on 121.5 MHz. The 406 MHz transmissions carry a unique beacon ID and, when available, GPS coordinates, which lets rescue networks quickly pinpoint the general distress location. The 121.5 MHz frequency serves as a backup by providing a continuous homing signal that rescuers can use to zero in on the beacon once they’re in the area, especially if satellite coverage is limited or during closer-stage rescue operations. The other options serve different roles: 156.8 MHz is the maritime distress calling channel, and 243 MHz is a military distress frequency, while 406 MHz is the modern satellite distress channel. In practice, beacons often emit on both 406 MHz and 121.5 MHz to maximize chances of being found quickly.

The system uses two paths to locate a distress beacon: a satellite-based alert on a dedicated 406 MHz channel and a nearby, ground-based homing signal on 121.5 MHz. The 406 MHz transmissions carry a unique beacon ID and, when available, GPS coordinates, which lets rescue networks quickly pinpoint the general distress location. The 121.5 MHz frequency serves as a backup by providing a continuous homing signal that rescuers can use to zero in on the beacon once they’re in the area, especially if satellite coverage is limited or during closer-stage rescue operations. The other options serve different roles: 156.8 MHz is the maritime distress calling channel, and 243 MHz is a military distress frequency, while 406 MHz is the modern satellite distress channel. In practice, beacons often emit on both 406 MHz and 121.5 MHz to maximize chances of being found quickly.