In which range is the cabin altitude the same as the aircraft altitude?

• A. Unpressurized range
• B. Pressurized range
• C. Emergency range
• D. Redundant range

Answer: (A)

Cabin altitude equals the aircraft altitude when there is no pressurization—i.e., in unpressurized flight. Without a pressure system maintaining a lower interior pressure, the cabin air simply tracks the outside air, so the interior altitude matches the aircraft’s altitude. In a pressurized range, the cabin is kept at a lower, breathable altitude regardless of how high the airplane flies, so the two do not match. An emergency depressurization would cause the cabin altitude to rise toward outside air, not stay equal. The term redundant range isn’t a standard category for cabin-pressure behavior.