Legal Briefing

Oxygen Requirements

You're taught early in your aviation training about potential medical risks associated with flying, including hypoxia, a condition caused by an inadequate oxygen supply to the body. The higher you fly, the thinner the air and the less oxygen available to keep your body and mind functioning properly. Every pilot needs to be aware that hypoxia and its debilitating effects are a real possibility when flying airplanes, and every pilot must know how to guard against it. To help the pilot in this regard, the FAA has put in place a regulation that identifies standard minimum altitudes where supplemental oxygen is required in the interest of safety.

First, let's consider just what hypoxia is. The FAA's Aeronautical Information Manual describes hypoxia as a state of oxygen deficiency in the body sufficient to impair functions of the brain and other organs. Symptoms associated with hypoxia include euphoria, a sense of well-being, or belligerence. Other symptoms include impairment of judgment, vision, memory, alertness, and coordination. Physical manifestations of the condition may include a blue tint to the skin under the fingernails and on the lips (cyanosis). In addition, a person suffering from hypoxia may feel sleepy or dizzy or have a headache. Eventually, hypoxia will lead to a loss of consciousness.

That this condition can be incapacitating is obvious, but the worst part is that its effects are insidious and difficult to recognize. What's more, not every person suffers the effects of hypoxia in the same way or under the same conditions. And the altitude at which hypoxia may occur can be lowered by such individual factors as a person's general health, smoking habits, use of medication or alcohol, fatigue, and anxiety. So, not everyone in the aircraft may be overcome by hypoxia at the same time. It is important to take precautions to prevent the onset of hypoxia and, if it does occur, to recognize the symptoms as early as possible.

Now, let's look at a regulation that is meant to guard against crew and passengers suffering from hypoxia during a flight. The regulation provides general standards and then specifically addresses pressurized aircraft. We will limit our discussion to the general requirements, which apply to all aircraft.

Part 91.211 of the federal aviation regulations (FARs), titled "Supplemental oxygen," states that,

"(a) General. No person may operate a civil aircraft of U.S. registry -

"(1) At cabin pressure altitudes above 12,500 feet (msl) up to and including 14,000 feet (msl) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

"(2) At cabin pressure altitudes above 14,000 feet (msl) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and

"(3) At cabin pressure altitudes above 15,000 feet (msl) unless each occupant of the aircraft is provided with supplemental oxygen."

Thus, the requirement for the crew to use supplemental oxygen begins at 12,500 feet cabin pressure altitude. Above that altitude, the required minimum flight crew, usually a single pilot in our typical general aviation flying, must use supplemental oxygen for any portion of the flight that lasts more than 30 minutes. Above 14,000 feet, the required minimum flight crew must use oxygen at all times. Above 15,000 feet, everyone on board the aircraft must be provided with supplemental oxygen. It's worth noting that while the crew must use the oxygen, passengers are not required to use it.

This is a regulatory requirement for the use and availability of "supplemental oxygen," which means any additional oxygen that may be supplied. This oxygen may come from oxygen equipment installed in the aircraft or from portable oxygen equipment carried on board the aircraft.

It is worth emphasizing that the standards are minimum standards. Every individual's need for oxygen is distinct and may be influenced by a number of factors. The regulation contemplates a normal, healthy pilot. It is not necessarily safe to assume that the regulatory requirement will be adequate for all individuals under all circumstances. In fact, while it is not mandated, the FAA says "for optimum protection, pilots are encouraged to use supplemental oxygen above 10,000 feet during the day, and above 5,000 feet at night."