Federal Aviation Regulations Practice Test

When operating an aircraft at cabin pressure altitudes above 12,500 feet MSL, supplemental oxygen is required during which time?

1. All flight time at those altitudes

2. Flight time in excess of 30 minutes at those altitudes

3. Only during takeoff and landing

4. During any passenger flight

The correct answer is: Flight time in excess of 30 minutes at those altitudes

The requirement for supplemental oxygen during flight at cabin pressure altitudes above 12,500 feet MSL is specifically mandated for flight time in excess of 30 minutes at those altitudes. This regulation is in place because, at higher altitudes, the availability of breathable oxygen decreases, leading to the risk of hypoxia. While some oxygen might be required at lower altitudes as well, the FAA stipulates that pilots and passengers must utilize supplemental oxygen only during times of extended exposure above the 12,500-foot threshold. When an aircraft operates above this altitude but under 14,000 feet, supplemental oxygen must be provided and used if the flight duration exceeds 30 minutes. For altitudes greater than 14,000 feet, oxygen must be used continuously. This gradual approach helps mitigate the potential physiological effects on pilots and passengers associated with lower oxygen levels. The other options do not align with the specific regulations related to supplemental oxygen use at altitude.