When should a pilot use augmented or emergency oxygen?

Using augmented or emergency oxygen is essential in specific scenarios related to cabin pressure. When cabin pressure is lost, it can lead to a condition known as hypoxia, where the body does not receive enough oxygen. This is particularly critical at altitudes above 14,000 feet MSL, where the partial pressure of oxygen decreases significantly, posing a risk of impaired cognitive and physical function. Therefore, a pilot must use supplemental oxygen to maintain adequate oxygen levels and ensure proper functioning of both body and mind in these circumstances.

At altitudes above 14,000 feet MSL, the risk of hypoxia increases, making it necessary to utilize emergency oxygen systems to prevent loss of consciousness or other incapacitating effects. This applies especially in unpressurized aircraft, where the external atmospheric pressure cannot be artificially raised. The requirement is well established in aviation regulations, emphasizing the importance of supplemental oxygen for pilots and passengers when flying in such conditions.