Supplemental oxygen for emergency descent and for first aid; turbine engine powered airplanes with pressurized cabins

This regulation requires Part 121 operators of turbine-powered pressurized aircraft to carry supplemental oxygen for emergencies.

Flight crew must have at least two hours of oxygen—enough for an emergency descent from maximum altitude to 10,000 feet in ten minutes, plus 110 minutes at 10,000 feet. Above FL250, pilots need quick-donning oxygen masks within immediate reach. Above FL410 (or FL350 for smaller aircraft), one pilot must continuously wear their mask unless both pilots have masks that can be donned one-handed within five seconds. If a pilot leaves the controls above FL410, the remaining pilot must wear their mask until the other returns.

Cabin crew above FL250 need either portable oxygen or sufficient equipment distributed throughout the cabin. Passengers must have oxygen available—at minimum, a 10% supply for 30 minutes on lower-altitude routes, or longer supplies on high-altitude routes. First-aid oxygen must also be available for passengers needing it after descending from above FL250.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*