What is required for all individuals on board when flying above 13,000 ASL?

When flying at altitudes above 13,000 feet above sea level (ASL), it is mandated by aviation regulations that all individuals on board an aircraft must use supplemental oxygen. This requirement is based on the physiological effects of high altitude, where the availability of oxygen decreases, and there is a risk of hypoxia for anyone not acclimated to such conditions.

At altitudes above this threshold, the cabin pressure may not provide sufficient oxygen for normal physiological function, thus necessitating the use of supplemental oxygen for everyone in the aircraft, including crew members and passengers. This regulation ensures safety during flights at high altitudes by preventing potential health hazards associated with low oxygen levels, such as loss of consciousness or impaired cognitive functions.