What altitude range requires supplemental oxygen for minimum crew according to regulations?

The regulation regarding the use of supplemental oxygen for crew members states that crew must have access to supplemental oxygen when operating at altitudes ranging from 12,500 feet Mean Sea Level (MSL) to 14,000 feet MSL for more than 30 minutes. This requirement is in place to ensure that crew members maintain adequate oxygen levels to function effectively and safely.

At altitudes above 14,000 feet MSL, the requirement for supplemental oxygen becomes more stringent, necessitating its use for all crew members at higher altitudes. This is due to the decreased partial pressure of oxygen at higher elevations, which can lead to hypoxia—a condition where the body is deprived of adequate oxygen supply.

Understanding this altitude requirement is crucial for flight safety, as it helps prevent the risks associated with high-altitude flying. In this context, the other options fall outside the specified range or do not align with the regulations concerning supplemental oxygen. Operations below 10,000 feet generally do not require supplemental oxygen for crew, while the ranges 10,000 feet to 12,000 feet and 15,000 feet and above have different regulations that do not pertain to the specified 30-minute time limit or varying crew needs. Thus, the correct