When do the passenger oxygen masks automatically deploy?

• A. 10,000 ft cabin altitude
• B. 12,000 ft cabin altitude
• C. 14,000 ft cabin altitude
• D. 16,000 ft cabin altitude

Answer: (C)

When cabin pressure is lost, the air inside becomes too thin for comfortable breathing, so the passenger oxygen system is designed to deliver oxygen automatically once the cabin altitude reaches a specific level. That level is about 14,000 feet, chosen to provide quick, reliable oxygen coverage for passengers as quickly as possible after decompression. This threshold helps ensure people don’t experience hypoxia while the aircraft descends to a safe, breathable altitude. The masks then remain supplying oxygen for the duration needed to reach lower altitude, typically long enough for the crew to descend and for the aircraft to maintain safe cabin conditions. Other altitude values listed aren’t used for standard passenger mask deployment.