When must all occupants on an aircraft use supplemental oxygen?

Supplemental oxygen is necessary for all occupants of an aircraft when flying at altitudes above 15,000 feet. This requirement is based on the physiological effects of decreased atmospheric pressure at higher altitudes, which can lead to hypoxia – a deficiency in the amount of oxygen reaching the tissues. At altitudes above 15,000 feet, the partial pressure of oxygen in the atmosphere decreases significantly, making it difficult for the human body to obtain sufficient oxygen.

Regulatory standards, such as those established by the FAA, specify that above this altitude, all passengers must utilize supplemental oxygen to ensure safety and prevent hypoxia. The need for supplemental oxygen becomes even more critical as altitude increases, illustrated by the requirements for pilots and crew members to use it at even lower altitudes in various circumstances. While the options for lower altitudes like 10,000 and 12,000 feet involve recommendations for pilot and crew oxygen requirements, the definitive guideline for all occupants to use supplemental oxygen begins at 15,000 feet.