What transponder code indicates communication failure?

What transponder code indicates communication failure?

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

Answer: (A)

Communications failure is indicated by the transponder code 7600. When a pilot loses radio contact, they set this code so ATC can recognize the situation and apply lost-communication procedures, continuing approach and sequencing based on radar observations alone. This code is distinct from the others: 7700 signals an emergency, requiring immediate action; 7500 indicates a hijacking; and 0000 is not a standard code used to denote communications failure. So 7600 is the correct code for communication loss.

Communications failure is indicated by the transponder code 7600. When a pilot loses radio contact, they set this code so ATC can recognize the situation and apply lost-communication procedures, continuing approach and sequencing based on radar observations alone. This code is distinct from the others: 7700 signals an emergency, requiring immediate action; 7500 indicates a hijacking; and 0000 is not a standard code used to denote communications failure. So 7600 is the correct code for communication loss.