What code must be set if communication is lost?

What code must be set if communication is lost?

• A. 7600
• B. 7700
• C. 7500
• D. 0000

Answer: (A)

When communication is lost, you signal this to ATC by setting the transponder to the radio failure code, 7600. This specific code is universally used to indicate loss of radio contact, so ATC knows you cannot communicate and will manage you under lost-communication procedures. The other codes correspond to different situations: 7700 means an emergency, 7500 indicates a hijack, and 0000 is not the standard signal used for lost communications. After selecting 7600, continue the flight under the appropriate lost-communications rules—prioritize the last assigned route and altitude, then the expected route, then the filed route if no further instructions are received, and try to re-establish contact as soon as possible.

When communication is lost, you signal this to ATC by setting the transponder to the radio failure code, 7600. This specific code is universally used to indicate loss of radio contact, so ATC knows you cannot communicate and will manage you under lost-communication procedures. The other codes correspond to different situations: 7700 means an emergency, 7500 indicates a hijack, and 0000 is not the standard signal used for lost communications. After selecting 7600, continue the flight under the appropriate lost-communications rules—prioritize the last assigned route and altitude, then the expected route, then the filed route if no further instructions are received, and try to re-establish contact as soon as possible.