What squawk code is used for a radio failure while airborne?

The correct squawk code for a radio failure while airborne is 7600. This code is specifically designated for situations where the aircraft experiences a loss of communication capability. When pilots cannot communicate with air traffic control or other aircraft due to radio failure, selecting squawk code 7600 signals to controllers that the aircraft is operating without radio communication, helping them manage air traffic effectively while ensuring the safety of the flight.

In contrast, other squawk codes are used for different scenarios: 7700 indicates an emergency situation, such as a serious in-flight issue; 7500 is reserved for situations involving unlawful interference, such as hijacking; and 7400 does not have a specific designation and is not commonly used in aviation. Understanding these codes helps enhance situational awareness and standardize communication protocols in the aviation industry.