What is the International Aeronautical Distress frequency for Aircraft?

• A. 121.5 MHz
• B. 243 MHz
• C. 2182 kHz
• D. 156.8 MHz

Answer: (A)

In aviation, emergencies have a globally designated voice channel that aircraft should use to call for help. The international aeronautical distress frequency in the VHF band is 121.5 MHz. This channel is monitored by air traffic services and search-and-rescue authorities worldwide, so a mayday call with location and aircraft identity can reach responders quickly. The other frequencies represent different services: 243.0 MHz is a UHF backup used by some aircraft (often military), not the primary international aeronautical distress frequency; 2182 kHz is a maritime distress frequency on the MF band; and 156.8 MHz is a maritime VHF channel, not reserved for aviation distress. Thus, 121.5 MHz is the one used for aircraft in distress.