> [!info] [§ 91.211 Supplemental oxygen](https://www.ecfr.gov/current/title-14/part-91/section-91.211#p-91.211(a)) > No person may operate a civil aircraft of U.S. registry $\rightarrow$ > > At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration; > > > At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and > > > At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen # [AIM 8-1-2(a)(6): Hypoxia](https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap8_section_1.html) - *Recommendations* for supplemental oxygen use 1. above 10,000 ft during the daytime 2. above 5,000 ft at night > Hypoxia is prevented by heeding factors that reduce tolerance to altitude, by enriching the inspired air with oxygen from an appropriate oxygen system, and by maintaining a comfortable, safe cabin pressure altitude. For optimum protection, pilots are encouraged to use supplemental oxygen above 10,000 feet during the day, and above 5,000 feet at night. The CFRs require that at the minimum, flight crew be provided with and use supplemental oxygen after 30 minutes of exposure to cabin pressure altitudes between 12,500 and 14,000 feet and immediately on exposure to cabin pressure altitudes above 14,000 feet. Every occupant of the aircraft must be provided with supplemental oxygen at cabin pressure altitudes above 15,000 feet. # Reasons for Regulations - Supplemental oxygen regulations and recommendations are used to provide a safe environment for flight crew and passengers that prevents the onset of [[Hypoxia]]