In automatic cabin pressurization, which component monitors cabin pressure and controls outflow valve to maintain the desired altitude?

In automatic cabin pressurization, which component monitors cabin pressure and controls outflow valve to maintain the desired altitude?

• A. Outflow valve alone regulates cabin altitude.
• B. The pressure controller automatically monitors cabin pressure and adjusts the outflow valve to maintain the desired cabin altitude.
• C. The crew manually controls altitude with an override.
• D. There is no automatic control; altitude is fixed.

Answer: (B)

Automatic cabin pressurization relies on a pressure controller that continuously monitors cabin pressure and automatically modulates the outflow valve to hold the cabin at the selected altitude. The cabin pressure sensor feeds the controller with the current cabin pressure. The controller compares this to the commanded cabin altitude (set by the crew) and adjusts the outflow valve position to vent more or less air from the cabin. Opening the valve venting more air lowers cabin pressure; closing the valve retains more air and increases pressure. This automatic loop maintains the desired altitude and also keeps the differential pressure within safe limits, responding smoothly to altitude changes during climb, cruise, and descent. The other statements don’t fit normal operation: the outflow valve alone isn’t responsible for maintaining altitude, since it needs the controller’s guidance; manual crew control with an override exists in some systems but the primary, everyday behavior is automatic; and there is automatic control in modern systems, not a fixed, unchanging altitude.

Automatic cabin pressurization relies on a pressure controller that continuously monitors cabin pressure and automatically modulates the outflow valve to hold the cabin at the selected altitude.

The cabin pressure sensor feeds the controller with the current cabin pressure. The controller compares this to the commanded cabin altitude (set by the crew) and adjusts the outflow valve position to vent more or less air from the cabin. Opening the valve venting more air lowers cabin pressure; closing the valve retains more air and increases pressure. This automatic loop maintains the desired altitude and also keeps the differential pressure within safe limits, responding smoothly to altitude changes during climb, cruise, and descent.

The other statements don’t fit normal operation: the outflow valve alone isn’t responsible for maintaining altitude, since it needs the controller’s guidance; manual crew control with an override exists in some systems but the primary, everyday behavior is automatic; and there is automatic control in modern systems, not a fixed, unchanging altitude.