Which components regulate cabin pressure differential and cabin pressure during ascent and descent?

• A. Outflow valves and pressurization controllers manage cabin pressure and differential pressure.
• B. Packs regulate all aspects of cabin pressure and temperature.
• C. The autopilot controls cabin pressure directly.
• D. Cabin pressurization is not managed actively in the A320.

Answer: (A)

The regulation of cabin pressure and its differential during climb and descent is handled by the outflow valve together with the cabin pressurization (pressure control) system. The cabin pressure controller continuously monitors the sensed cabin altitude and the differential pressure, comparing them to the selected targets. It then adjusts the position of the outflow valve to let more or less air escape from the cabin, maintaining the desired cabin pressure and keeping the differential within safe limits. The packs focus on conditioning and supplying air for temperature and ventilation, not on maintaining cabin pressure. The autopilot doesn’t directly control cabin pressure; pressurization follows the automatic controller to manage ascent and descent. Safety relief valves provide backups in case of abnormal pressure, but normal regulation is by the pressurization controller and the outflow valve.