Loss on which systems when using Audio Control Panel backup?

Loss on which systems when using Audio Control Panel backup?

• A. Navaid Identification, TCAS, MDP, audio tones
• B. Flight Data Recorder, Windshear, autopilot
• C. Engine instruments, fuel indicators
• D. Cabin pressurization, smoke detector

Answer: (A)

When the Audio Control Panel is in backup mode, the number of active audio paths is reduced to keep essential communications going, but some navigation and alert audio channels are no longer available. The items tied to the ACP for audible output—navaid identification, TCAS traffic alert audio, MDP-related audio, and general audio tones—are the ones that can be lost. This happens because those sources rely on the ACP’s routing, which is limited in backup mode. Other systems like the Flight Data Recorder, Windshear alerts, autopilot, engine instruments, fuel indicators, cabin pressurization, and smoke detectors don’t depend on the ACP’s audio routing, so they stay unaffected.

When the Audio Control Panel is in backup mode, the number of active audio paths is reduced to keep essential communications going, but some navigation and alert audio channels are no longer available. The items tied to the ACP for audible output—navaid identification, TCAS traffic alert audio, MDP-related audio, and general audio tones—are the ones that can be lost. This happens because those sources rely on the ACP’s routing, which is limited in backup mode. Other systems like the Flight Data Recorder, Windshear alerts, autopilot, engine instruments, fuel indicators, cabin pressurization, and smoke detectors don’t depend on the ACP’s audio routing, so they stay unaffected.