Which frequency is primarily used as a distress frequency for radiotelephony?

The choice of 2182 kHz as the primary distress frequency for radiotelephony is based on its international recognition and usage in maritime communication. This frequency is specifically allocated by the International Telecommunication Union (ITU) for distress and calling purposes, making it a standard for distress signals.

When ships encounter emergencies, they use 2182 kHz to send out distress calls, ensuring that other vessels and coast stations monitor that frequency for any urgent communications. This frequency is monitored continuously by vessels and coastal stations to provide immediate response capability.

In contrast, while the other frequencies listed may have specific uses in marine or aviation communication, they are not designated as primary distress frequencies. For instance, although 156.800 MHz is used for VHF marine communications, it does not have the same international standardization for distress calls as 2182 kHz does.