Which frequency is primarily used for distress communication in maritime radio?

For distress communication in maritime radio, the frequency primarily used is 121.500 MHz. This frequency is internationally recognized as the emergency frequency for aviation and maritime distress and is monitored continuously by search and rescue organizations. It serves as a primary frequency for emergency beacons and is crucial for distress signaling, making it vital for emergency response in maritime situations.

The other frequencies listed serve different purposes. For instance, 156.000 MHz is a VHF maritime channel often used for routine communications and bridge-to-bridge communications, but it is not the primary distress frequency. The 406 MHz frequency is associated with satellite emergency location transmitters which can be used for more precise geo-location in distress situations, although 121.500 MHz is the original distress frequency used by vessels. Additionally, 162.400 MHz is typically used for weather information broadcasts and is not designated for emergencies. Understanding these frequency designations is critical for effective communication and safety in maritime operations.