When the active Cabin Pressure Controller fails, what happens automatically?

• A. Automatically switches to standby controller
• B. Shuts the cabin pressure system down
• C. Switches to manual pressure control by the crew
• D. Issues a high altitude warning

Answer: (A)

Redundancy in the cabin pressure system centers on an active controller and a standby controller that both manage the same outflow valve to regulate cabin pressure. If the active CPC fails, the system automatically transfers control to the standby CPC, continuing to regulate cabin pressure without input from the crew. This automatic switchover keeps the cabin altitude and rate on the programmed schedule, maintaining safe and comfortable conditions.

Shutting the system down isn’t the automatic action in this failure mode, because the design aims to keep pressurization operable. Switching to manual control by the crew isn’t the automatic response either; manual control would only come into play if both CPCs failed or in a different fault scenario. A high altitude warning may appear as part of the fault indicators, but the primary automatic action is the seamless handover to the standby controller.