Supplemental passenger oxygen masks can be actuated by the flight deck, or automatically at what cabin altitude range?

• A. 12,000 +/- 500 feet
• B. 14,000 +/- 500 feet
• C. 16,000 +/- 500 feet
• D. 18,000 +/- 500 feet

Answer: (B)

Supplicant passenger oxygen masks are tied to the cabin altitude sensor, so they deploy automatically when the cabin altitude rises to about 14,000 feet (plus or minus 500 feet). This threshold is chosen so oxygen is available quickly during a decompression without causing nuisance deployments during normal flight where cabin altitude is kept much lower. The flight deck can also trigger mask deployment manually if needed, using the oxygen control in the cockpit. The other altitude options are outside the standard automatic deployment range, which is why they aren’t used.