Final answer:
Pilots must wear O2 masks when flying at cabin pressure altitudes above 12,500 feet for extended periods or immediately at altitudes above 14,000 feet, and during emergency depressurization to prevent hypoxia.
Step-by-step explanation:
Pilots need to wear O2 masks in situations where the cabin pressure is not sufficient to provide adequate oxygen for them to function properly, such as at high altitudes or in the event of cabin depressurization. At altitudes above 10,000 feet, the partial pressure of oxygen is too low to adequately oxygenate hemoglobin in the blood, leading to hypoxia. Should cabin pressure fall, supplemental oxygen provided by the masks ensures that pilots can breathe normally despite the reduced atmospheric pressure.
This is critical for maintaining cognitive functions and the ability to perform flight tasks. The FAA has set regulations that determine when oxygen masks must be used to ensure the safety of both passengers and crew. For example, pilots must use oxygen any time they are flying at cabin pressure altitudes above 12,500 feet for more than 30 minutes or immediately at altitudes above 14,000 feet. Additionally, if there's an emergency that results in a loss of cabin pressure, masks are deployed automatically for all occupants.