If the primary cabin pressure controller becomes unavailable, the system will

• A. Continue using the primary controller until failure detected
• B. Switch automatically to the second cabin pressure controller
• C. Shut down the pressurization system
• D. Require manual reversion by crew

Answer: (B)

Redundancy and automatic failover in the cabin pressurization system are designed so a failure in the primary controller doesn’t disrupt cabin pressure. When the primary cabin pressure controller becomes unavailable, the system automatically hands control to the secondary controller. The secondary controller then regulates the outflow valve to maintain the desired cabin pressure and altitude, ensuring continuous pressurization without crew action. This automatic switch avoids continuing with a failed primary, avoids a system shutdown, and eliminates the need for manual reversion, which is why the automatic transfer to the second controller is the correct behavior.