The cabin pressure controller provides the crew with a means to control the pressurization system.

The cabin pressure controller provides the crew with a means to control the pressurization system.

• A. It regulates cabin temperature.
• B. It provides a means to vary cabin altitude.
• C. It opens automatically to depressurize.
• D. It seals the cabin from outside air.

Answer: (B)

The essential idea is that pressurization is about setting and holding a desired cabin altitude by controlling how much air leaves the cabin. The cabin pressure controller lets the crew select a cabin altitude setpoint and then drives the outflow valve to achieve and maintain that level. By adjusting the valve, it balances the air coming in with the air escaping, keeping the cabin at the chosen pressure differential and altitude. This function is distinct from regulating cabin temperature, which is done by the environmental control system; it’s not about automatically venting to depressurize in normal operation, and it isn’t the mechanism that seals the cabin from outside air—those are structural and valve-related roles separate from the controller’s setpoint function.

The essential idea is that pressurization is about setting and holding a desired cabin altitude by controlling how much air leaves the cabin. The cabin pressure controller lets the crew select a cabin altitude setpoint and then drives the outflow valve to achieve and maintain that level. By adjusting the valve, it balances the air coming in with the air escaping, keeping the cabin at the chosen pressure differential and altitude.

This function is distinct from regulating cabin temperature, which is done by the environmental control system; it’s not about automatically venting to depressurize in normal operation, and it isn’t the mechanism that seals the cabin from outside air—those are structural and valve-related roles separate from the controller’s setpoint function.