Which action sequence correctly enables a cabin announcement on the Public Address System?

• A. Press PA switch light on the Interphone Control Unit only
• B. Move the transmit switch on the audio control panel to PA, then press PA switch light on the Interphone Control Unit
• C. Speak into the cockpit microphone without selecting PA
• D. Use the aircraft interphone without enabling PA

Answer: (B)

To broadcast to the cabin, you must route the microphone signal to the Public Address system and then arm the PA path. Move the transmit selector on the audio control panel to PA so the cockpit mic audio is sent to the PA bus, then press the PA switch light on the Interphone Control Unit to enable the cabin announcement. If you simply press the PA switch without selecting PA, or speak into the cockpit microphone without choosing PA, or try to use the interphone without enabling PA, the message won’t reach the passengers. The two-step sequence ensures the signal is directed to the PA system and then actively broadcast to the cabin.