At what altitude are quick-donning masks required in aviation?

Quick-donning masks are required in aviation at an altitude of 25,000 feet and above. At this altitude, pilots and crew members may be exposed to environments where supplemental oxygen is necessary due to reduced atmospheric pressure, which can impair cognitive and physical functions. The quick-donning feature allows the mask to be put on swiftly, ensuring that crew members can effectively manage their oxygen needs without wasting valuable time, especially during emergency situations. This requirement is part of safety regulations aimed at ensuring pilots maintain the highest levels of awareness and capability while operating at higher altitudes where the risk of hypoxia increases.