In emergencies, pilots must use specific transponder codes to communicate their situation. Here are the key codes: EMERGENCY – Mode 3A Code 7700. This code is crucial for alerting air traffic control. However, if an aircraft is already receiving air traffic services and has a different code, it should keep that code. COMMS FAILURE – Mode 3A Code 7600. This indicates a communication issue. UNLAWFUL INTERFERENCE – Mode 3A Code 7500. This alerts authorities to potential hijacking.
For aircraft that are not in contact with air traffic services, the first step in an emergency is to switch to the EMERGENCY code (Mode 3A Code 7700). According to ICAO Doc 8168 Vol 1, a pilot can choose this code whenever they believe it is necessary. This proactive approach ensures that help can be dispatched quickly.
