Story ID: 112
High-altitude Oxygen Rule: Compliance Conundrum
By: AIN Staff
Caption: The requirement for an oxygen mask above 41,000 feet might create more problems than it solves, say some pilots.
Word Count: 587
Most professional pilots are diligent about following the rules except, of course, on those relatively rare occasions when they don’t agree with them. One of the standouts among ignored rules is 91.211, which governs the use of supplemental oxygen, said Rick Miller, chief pilot for Merck Sharp & Dohme, at the recent Business Aviation Safety Summit. The rule requires that above 41,000 feet, one pilot must use the mask at all times even with another pilot in the cockpit. The pragmatic reason behind 91.211 is to ensure pilots can maintain control of the aircraft in the event of a high-altitude explosive decompression. At 50,000 feet, the time of useful consciousness is a mere six to nine seconds, about the time that passes between pulling the power to idle over the threshold and touching down on the runway.
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“This regulation as it applies to the use of supplemental oxygen above 41,000 feet is probably one of the clearest in Part 91,” he said. However, he maintained, non-compliance seems to be the norm, and incidents of non-compliance are not the result of pilots who don’t understand the rules, Miller noted. He cited an NTSB study of 500 Part 91 pilots that asked whether they use their masks above 41,000. Only 18 percent said yes. “It’s important as a chief pilot to maintain a high level of safety and professionalism in my organization and a good safety culture,” he added. “This regulation is one of the biggest challenges I’ve had over the years. But how do you operate a disciplined cockpit environment when people cherry pick the regulations they’ll follow? There must be a better way.”

If so many pilots ignore the rule, should the industry force it on violators, or should the rule be tweaked to align with Europe’s regulations, which recommend the use of oxygen above 41,000 feet? “The FAA and NTSB don’t seem concerned about addressing this situation,” Miller said. “I’m frustrated that I’m one of the few [chief pilots] out there forcing my pilots to comply. I don’t know why the FAA and NTSB don’t look at this more closely.” Miller is currently working with Gulfstream and others to better understand why there is so much disregard for the regulation, as well as potential solutions. One insight that emerged early in the session was that the quick-donning masks are normally considered emergency equipment. What company operates an aircraft regularly using a piece of emergency equipment?

Miller said the arguments for or against a change to the regulation must focus on determining the severity of the threat facing flight crews when they avoid wearing the masks at high altitude. “What’s our tolerance for this kind of situation when a rapid decompression could translate into the loss of lives?” Miller wondered, especially in light of the certification standards on many new high-altitude-capable aircraft? “[Manufacturers] had to prove a rapid decompression is a one in a billion chance. This is such a highly unlikely event it is really considered an acceptable risk.”

Changing the FAA’s mind about anything is no small challenge. Miller said some recent SMS risk assessments he conducted uncovered a list of problems created by wearing oxygen masks for extended periods at high altitude that he believes might support a change. A series of instant polls conducted at the summit by Francois Lassale of Vortex FSM added fuel to the fire for a pragmatic change to the 91.211 problems (see box).