How is cabin pressurization controlled on an ATR and what ensures safe cabin altitude?

• A. An automated pressurization controller maintains cabin altitude by adjusting the outflow valve and monitoring sensors to limit differential pressure.
• B. Crew manually sets a fixed cabin altitude with a static outflow valve.
• C. Cabin altitude is not controlled and remains at ambient pressure.
• D. A purely mechanical valve regulates cabin altitude without sensors.

Answer: (A)

The cabin is kept at a safe, comfortable altitude by an automated pressurization controller that continuously reads cabin pressure and the differential pressure across the fuselage. It automatically adjusts the outflow valve to vent or retain air, maintaining the chosen cabin altitude while keeping the pressure difference within structural limits. Safety is provided by monitoring sensors and by relief mechanisms that open if the differential pressure would exceed its maximum, preventing over‑pressurization. In normal operation the system manages the pressurization automatically, so crew intervention isn’t required for altitude control.