What is required for aircraft flying between 10,000 and 13,000 feet regarding oxygen?

When flying at altitudes between 10,000 and 13,000 feet, the regulations specify that supplemental oxygen must be provided to the crew members and a portion of the passengers. Specifically, if the flight is above 10,000 feet for more than 30 minutes, the crew must utilize oxygen. Additionally, the regulations mandate that at least 10% of the passengers must also be provided with supplemental oxygen.

The requirement reflects safety considerations, as the partial pressure of oxygen decreases with altitude, and it is crucial to ensure that everyone on board is adequately supplied with oxygen to prevent hypoxia, particularly in prolonged exposure situations. This not only prioritizes crew safety, who are responsible for operating the aircraft, but also considers the welfare of the passengers.

Other answers do not fully comply with the established regulations for oxygen supply for both crew and passengers at these altitudes, leading to their exclusion as correct choices.