What is required for crew members at cabin pressure altitudes above 14,000 feet?

At cabin pressure altitudes above 14,000 feet, it is mandatory for crew members to use supplemental oxygen for the entire duration of the flight. This requirement is based on physiological considerations; as altitude increases, the partial pressure of oxygen decreases, which can impair cognitive and physical functioning. At overall altitudes above 14,000 feet, the risk of hypoxia (insufficient oxygen supply to the body) increases significantly. Consequently, in order to maintain optimal performance and ensure safety, crew members must have continuous access to supplemental oxygen.

This regulation helps to prevent adverse effects that could compromise both the safety of the crew and the passengers, reinforcing the importance of adherence to safety protocols in aviation operations.