When is minimum flight crew oxygen required according to part 91?

Minimum flight crew oxygen is required at or above 12,500 feet in accordance with aviation regulations. This requirement ensures that flight crew members have access to supplemental oxygen due to the decreased availability of breathable oxygen at higher altitudes. Above this altitude, the atmospheric pressure significantly drops, which can lead to hypoxia, a condition caused by insufficient oxygen available to the body.

The regulation is designed to maintain a safe working environment for the flight crew, allowing them to operate the aircraft effectively and respond to any emergencies that may arise at higher altitudes. By requiring oxygen starting at 12,500 feet, aviation authorities prioritize crew health and the safety of the flight operation. Issues of cabin pressure and oxygen deprivation become increasingly critical as the altitude rises, making this specific threshold a key aspect of flight safety standards.