At what altitude is oxygen required to be provided to the crew for two hours?

• A. 8,000 ft for two hours
• B. 9,000 ft for two hours
• C. 10,000 ft for two hours
• D. 12,000 ft for two hours

Answer: (C)

Oxygen for crew is required once the flight climbs high enough that ambient air can no longer reliably meet everyone’s needs, and the two-hour duration is the period the policy uses to ensure safety while a rapid descent or fix is arranged. Ten thousand feet is the threshold used here, so the crew must have access to oxygen for at least two hours starting at that altitude. At lower altitudes, the standard two-hour oxygen requirement doesn’t apply in this context, while higher altitudes would still involve oxygen but the question specifies the two-hour rule at ten thousand feet. This is why ten thousand feet for two hours is the best answer.