What squawk code corresponds to lost communications (radio failure)?

What squawk code corresponds to lost communications (radio failure)?

• A. 7500
• B. 7600
• C. 7700
• D. 7777

Answer: (B)

When communications are lost, the aircraft should signal this with the transponder code 7600. This code immediately tells air traffic control that the pilot cannot communicate, triggering lost‑communication procedures so ATC can manage traffic and provide guidance based on the last clearance and the filed route. Other common squawks have different meanings: 7500 indicates a hijacking, 7700 signals a general emergency, and 7777 is not a standard civilian squawk. In practice, after selecting 7600, an IFR flight follows the last assigned route and altitude and proceeds with the filed or expected clearance while attempting to reestablish contact.

When communications are lost, the aircraft should signal this with the transponder code 7600. This code immediately tells air traffic control that the pilot cannot communicate, triggering lost‑communication procedures so ATC can manage traffic and provide guidance based on the last clearance and the filed route. Other common squawks have different meanings: 7500 indicates a hijacking, 7700 signals a general emergency, and 7777 is not a standard civilian squawk. In practice, after selecting 7600, an IFR flight follows the last assigned route and altitude and proceeds with the filed or expected clearance while attempting to reestablish contact.