What are the oxygen requirements for part 91 at and above 12,500 feet?

The option that states that minimum flight crew is required to use oxygen if flying at or above 12,500 feet for 30 minutes or more is correct because it aligns with the regulations set forth by the Federal Aviation Administration (FAA) concerning oxygen use in aviation. Specifically, the FAA mandates that for flights conducted at altitudes between 12,500 feet and 14,000 feet, the flight crew must utilize supplemental oxygen for any portion of the flight exceeding 30 minutes. This is essential as the atmospheric pressure decreases at higher altitudes, leading to diminished oxygen availability, which can affect cognitive and physical performance.

While the decision for passenger oxygen use at these altitudes is not specifically limited to needing to be on oxygen for the entire duration, the regulations do require that oxygen must be available for passengers if the aircraft operates above 14,000 feet, ensuring everyone's safety. Therefore, having a clear understanding of these specific requirements helps pilots and crew manage in-flight safety protocols effectively when flying at higher elevations.