At cabin pressure altitudes above 12,500 feet MSL up to 14,000 feet MSL, supplemental oxygen shall be used for flight time in excess of how many minutes?

• A. 15
• B. 30
• C. 45
• D. 60

Answer: (B)

When flying at high cabin altitudes, the air is thinner and the body gets less oxygen, which can lead to hypoxia if you stay exposed too long. Regulations address this by setting oxygen requirements for unpressurized aircraft.

In the range from 12,500 feet up to 14,000 feet MSL, supplemental oxygen must be used for the time beyond 30 minutes of flight. So if you fly 40 minutes in that altitude band, you’d need to have and use oxygen during the portion after the first 30 minutes. If your flight is only 25 minutes, oxygen wouldn’t be required yet. This 30-minute threshold is the reason the correct choice is 30 minutes.