Under 14 CFR 91.211, what supplemental oxygen requirement applies to flight crew members in unpressurized aircraft at cabin pressure altitudes above 12,500 feet MSL up to and including 14,000 feet MSL?
- ARequired for that part of the flight at those altitudes that is of more than 30 minutes d…
- BRequired continuously for the entire duration of flight above 12,500 feet MSL
- CRequired only for operations at night or during IMC conditions
- DOptional for flight crew but mandatory for all passengers