Which component limits cabin altitude to approximately 12,500 +/- 1,500 feet?

Which component limits cabin altitude to approximately 12,500 +/- 1,500 feet?

• A. Ram air system
• B. Cabin pressure controller
• C. Quick dump valve
• D. Altitude pressure regulator

Answer: (D)

The device that sets and caps how high the cabin can pressurize is the altitude pressure regulator. It controls the maximum pressure fed into the cabin, effectively limiting the cabin altitude to about 12,500 feet with some tolerance (±1,500 feet). As the airplane climbs and the demand for cabin pressure would normally increase, the altitude pressure regulator holds the supply to a fixed ceiling, so the cabin altitude stays around that level. The cabin pressure controller and the outflow valve then work within that limit to maintain the desired cabin environment, while other systems like the ram air system or quick dump valve do not set this ceiling.

The device that sets and caps how high the cabin can pressurize is the altitude pressure regulator. It controls the maximum pressure fed into the cabin, effectively limiting the cabin altitude to about 12,500 feet with some tolerance (±1,500 feet). As the airplane climbs and the demand for cabin pressure would normally increase, the altitude pressure regulator holds the supply to a fixed ceiling, so the cabin altitude stays around that level. The cabin pressure controller and the outflow valve then work within that limit to maintain the desired cabin environment, while other systems like the ram air system or quick dump valve do not set this ceiling.