When flying at an altitude of 11,500 feet ASL for 45 minutes, how long is Oxygen required?

At altitudes above 10,000 feet ASL, supplemental oxygen is required due to the decrease in atmospheric pressure and the corresponding decrease in the partial pressure of oxygen, which can lead to hypoxia. Regulations stipulate that if flying at an altitude of 10,000 feet ASL to 12,500 feet ASL, supplemental oxygen must be used if the flight exceeds 30 minutes. Specifically, at 11,500 feet ASL, oxygen is required for any flight duration beyond 30 minutes.

In this scenario, since the flight lasts for 45 minutes at 11,500 feet ASL, the use of supplemental oxygen is mandated for the entire duration of the flight, which is 45 minutes. Therefore, one must use oxygen throughout the flight to ensure pilot safety and prevent hypoxia, making it necessary to have oxygen for the complete 45 minutes. This aligns with the aviation safety regulations that are in place to protect pilots at challenging altitudes.