Decompression occurs when?

• A. When the aircraft cannot maintain needed cabin air pressure
• B. When oxygen supply is unlimited
• C. When cabin air becomes humid
• D. When outside temperature drops

Answer: (A)

Decompression means the aircraft can no longer maintain the required cabin air pressure. In flight, the cabin is kept at a higher pressure than the outside air so passengers feel as if they’re at a much lower altitude. If the pressurization system fails or a breach occurs, the cabin can no longer hold that pressure, and air rushes out toward the lower outside pressure. This drops the cabin altitude and, if not corrected quickly, can lead to inadequate oxygen for everyone on board. The immediate response is to provide oxygen to passengers and crew and, usually, to descend to a safer altitude where breathing air is comfortable. The other factors—oxygen supply being unlimited, cabin air becoming humid, or outside temperature dropping—do not cause decompression; they relate to other cabin conditions or environmental factors, not the loss of pressurization.