A. System FunctionThe interphone system lets the flight crew speak to each other, the cabin crew and the ground crew.
B. System ComponentsThe primary components of the system is the ground-crew jack box. (Ref. Fig. 1 and Fig. 2)
C. System Operation
- The audio signals from the ground crew are sent to the No. 1 Audio Control Panel (ACP) (Ref. 23-51-00) through the ground-crew jack box. These audio signals are then sent as output to the flight crew headsets. Audio signals from the flight crew microphones are sent to the ground-crew jack box through the No. 1 ACP.
- The audio signals from the cabin crew are sent to the No. 1 and the No. 2 ACP from the Cabin Audio System (CAS) (Ref. 23-31-00). These audio signals are then sent as outputs to the flight crew headsets. The audio signals from the flight crew microphones are sent to the CAS through the No. 1 and the No. 2 ACP.
- The pilot, the co-pilot and the third crew member speak to each other through the interphone bus.