At which altitude must all persons aboard be provided with supplemental oxygen?

The requirement for providing supplemental oxygen to all persons aboard is dictated by federal aviation regulations, which state that oxygen must be used when flying at altitudes where the risks of hypoxia become significant. Specifically, at altitudes above 15,000 feet MSL (Mean Sea Level), supplemental oxygen must be available for all occupants on board the aircraft.

At this altitude, the partial pressure of oxygen decreases, and the onset of hypoxia can occur, especially during prolonged exposure. This regulation is in place to ensure the safety and health of all individuals on the flight, preventing the physiological effects associated with low oxygen levels in the blood.

While supplemental oxygen is also recommended at lower altitudes, such as above 10,000 feet for pilots and above 12,000 feet for extended periods, the specific requirement for all persons aboard to have supplemental oxygen is established at 15,000 feet. This underscores the importance of being proactive in providing oxygen to prevent adverse health effects in a properly regulated and compliant manner.