When operating between 12,500 feet MSL and 14,000 feet MSL, how long must supplemental oxygen be used during the flight?

When operating between 12,500 feet MSL and 14,000 feet MSL, the regulation states that pilots must use supplemental oxygen for any flight time exceeding 30 minutes at these altitudes. This rule is crucial because, at these elevations, the partial pressure of oxygen decreases, which can lead to hypoxia—an insufficient amount of oxygen in the body.

The requirement to use supplemental oxygen beyond 30 minutes at these altitudes helps to ensure that pilots maintain adequate oxygen levels to perform tasks safely and avoid impaired judgment, decreased cognitive function, or other effects of hypoxia.

While it is important for pilots to be aware of the risks associated with altitude and oxygen saturation, the regulations do not mandate supplemental oxygen for the entire duration of the flight at or above these elevations, nor is it limited only to the takeoff and landing phases. This distinction is important for pilot awareness and compliance during prolonged operations at elevated altitudes.