If you ask private pilots when they should start using supplemental oxygen during a flight, most of them will parrot back the verbiage that appears in the FAR AIM under regulation 91.211: “After 30 minutes if you go above 12,500 feet MSL.”
The regulation actually reads: “No person may operate a civil aircraft of U.S. registry at a cabin pressure altitude 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.”
To some, the regulation gives the impression that the physical and mental effects of oxygen deprivation won’t be felt until reaching 12,500 MSL.
That’s not necessarily so, says Patrick McLaughlin, the owner and founder of Mountain High Oxygen Systems, which makes portable supplemental oxygen systems for aircraft ranging from gliders and balloons to jets.
“The regulation is antiquated,” says McLaughlin, “and not necessarily based on physiology, but rather on the fact that it took a DC-3 no more than 30 minutes to go over the Rocky Mountains.”
According to McLaughlin, a pilot’s performance may degraded significantly before reaching that altitude, and unless there is an accident or incident the pilot would have no idea he or she is compromised.
Hypoxia, also known as hypoxemia, is a condition when there is an insufficient supply of oxygen in the blood. It can be caused by low partial pressure of atmospheric oxygen, such as what occurs when flying at high altitudes, inadequate pulmonary ventilation (problems with the pilot or passengers pulmonary systems), and carbon monoxide poisoning.
Symptoms of hypoxemia can include increased reaction time, fatigue, mental confusion, headaches or a feeling of euphoria similar to drunkenness.
The symptoms and their severity vary from pilot to pilot and can be influenced by a number of factors, including the age of the pilot, the pilot’s level of physical fitness and whether the pilot is a smoker.
Pilots who use supplemental oxygen before the regulation-required altitude can avoid these symptoms. “We recommend that they use it at 8,000 feet during the day and at 5,000 feet at night,” says Robert Jamieson, CEO of Mountain High. “We have testimonials from our customers who say when they use supplemental oxygen they have less headaches and don’t arrive feeling tired out.”
A non-fatigued pilot is a safer pilot, notes McLaughlin.
“We’ve been studying the accident reports from the National Transportation Safety Board,” he said. “They show that three-quarters to as many as four-fifths of the aircraft that crashed had no pre-crash mechanical problems, but the NTSB noted that the accidents happened during or at the end of a long cross country flight. Fatigue probably was a factor.”
McLaughlin predicts that the required altitude for supplemental O2 will be lowered when the FAA takes the time to reconsider the regulation given all that has been learned in the past several decades about oxygen deprivation and its impact on pilots.
Unfortunately, the after-the-flight headache is part of the aviation culture, says Jeff Callahan, a 1,400-hour pilot and director of sales for Aerox Aviation Oxygen Systems, a company that supplies supplemental oxygen systems for aircraft.
“These pilots think that flying for four hours automatically means you’re going to get a headache, like it is an occupational hazard,” he said. “They write it off as dehydration, when it is really hypoxemia. It doesn’t have to be that way,” he said. “Traveling four hours in an airplane should be no different than riding four hours in a car.”
HOW MUCH DOYOU NEED?
Some pilots resist getting supplemental oxygen systems because they are concerned about the weight and complexity of the units.
The invention of the pulse-demand oxygen system has taken a lot of the mental math and guesswork out of using the units, company officials say.
According to McLaughlin, the pulse-demand systems sense when your body needs more oxygen and supply it.
“Instead of a big bulky thing that looks like an attachment to a vacuum, it’s a small electrical box,” he said. “Some of our clients are doctors and anesthesiologists who took it on themselves to try it and say that it really gives you the oxygen you need when you need it — kind of like a fuel injection computer that knows when to inject more fuel into the engine. The unit monitors your heart and how long you have been at that altitude and adjusts accordingly.”
“No one wants to have to keep making adjustments to the flow of oxygen,” Jamieson added. “Now the computer detects the altitude changes so there is no fiddling of the knobs by the pilot.”
According to Lloyd Boston, an engineer with Aerox, another factor that has made the systems more convenient is the development of conserving cannules that allow the user to get more use out of an oxygen bottle.
“We basically breathe like a four-stroke engine,” he explained. “You take a breath, you rest, and you breathe out. When you are not breathing, the conserving cannula has a reservoir built into it that saves the oxygen until you take your next breath. The oxygen isn’t wasted.”
Another factor that makes oxygen more user friendly is that the systems are more reliable than they were decades ago.
“Many of the excuses for not using supplemental oxygen have gone by the wayside,” said McLaughlin.
NOT JUSTFOR PILOTS
Although pilots will benefit the most from supplemental oxygen, it is beneficial for passengers too, according to McLaughlin. One of Mountain High’s most popular units is the pulse-demand O2D2 unit, which provides supplemental oxygen for both the pilot and the front-seat passenger.
“Our customers tell us all the time things like ‘my wife didn’t like flying with me until I got the O2D2 in my airplane,'” McLaughlin said. “‘Now she doesn’t get headaches when we fly.'”
The cost of the units is not cheap, but usually they are not more than the price of a good headset, company officials noted — “and they are more safety orientated than a headset,” said Boston.
“If you are going to buy an airplane you really should consider getting a supplemental oxygen system to go with it,” added Callahan.