What is cabin pressure?

• A. The pressure outside the aircraft doors
• B. The pressure inside the aircraft cabin, regulated to maintain passenger comfort and safety at altitude
• C. The pressure in the baggage hold
• D. The pressure of the air in the cockpit

Answer: (B)

Cabin pressure is the air pressure inside the aircraft cabin that is actively controlled to keep the air breathable and comfortable for passengers and crew at high altitudes. Even though the outside air at cruising level is very thin, the airplane’s environmental control system maintains the cabin at a lower “altitude” equivalent—typically around 6,000–8,000 feet—so oxygen levels stay adequate and fatigue is minimized. This regulation is achieved through the system’s use of bleed air and outflow valves to hold a safe differential between the inside and outside. It’s different from the pressure outside the aircraft or in the baggage hold, and it’s the controlled air environment that keeps flying comfortable and safe. If a loss of cabin pressure occurs, oxygen systems are designed to provide breathable air to occupants.