More than 60 percent of business jet pilots do not use oxygen masks when required to by FAA regulations, according to a survey conducted by corporate pilot Chris Shaver for his master’s thesis at Embry-Riddle Aeronautical University.

Shaver needed a safety-related project for his thesis and he didn’t want to rehash existing research on subjects that have been studied exhaustively. “The question came up in hangar talk with some friends,” he recalled. One pilot questioned whether oxygen masks are certified above a certain altitude, then the discussion moved into whether pilots typically wear the mask as required by FAA regulations. Shaver posed that question as a basis for his research.

The FAA requires pilots to wear an oxygen mask under certain circumstances, and Shaver’s research showed that most pilots do not comply with the rules. For Part 91 operators, no one may fly a pressurized aircraft above 35,000 feet without one pilot donning a mask. If quick-donning masks are available, the threshold altitude rises to 41,000 feet. Above 41,000 feet or if one pilot leaves the controls above 35,000 feet, one pilot “must always be using supplemental oxygen.”

Part 135 pilots must use supplemental oxygen above 25,000 feet when one pilot is at the controls. When both are flying, one must be on oxygen above 35,000 feet. Part 121 pilots have a 35,000-feet threshold when one pilot is at the controls or when flying above 35,000 feet in an aircraft with fewer than 30 seats or above 41,000 feet with more than 30 seats.

EASA rules, still under the JAR-OPS system, approach this issue from a different philosophy, requiring use of supplemental oxygen only “whenever cabin altitude exceeds 10,000 feet for a period in excess of 30 minutes and whenever the cabin altitude exceeds 13,000 feet.” Transport Canada combines the two philosophies, requiring use of supplemental oxygen at cabin altitudes of more than 10,000 feet and at any time above 41,000 feet.

The majority of those who participated in the survey do not take the FAA regulations for oxygen use seriously, according to Shaver’s results. “While there is ample research, regulation and training available to pilots with regards to hypoxia and high-altitude cabin decompression,” Shaver summarized, “an alarming number of aviators tend to [adopt] the ‘it will not happen to me’ attitude when faced with using supplemental oxygen. Many pilots think that the chance of an explosive decompression is so rare that the risks associated with no oxygen mask at high altitudes do not outweigh the potential rewards.”

Shaver aimed the 12-question survey at pilots who typically fly above 25,000 feet. There were 548 respondents, and 94 percent of those fit that target. By type of operation, 240 respondents fly Part 91, 164 Part 121, 92 Part 135, 22 military and 30 none of the above or other.

Only 21 percent of Part 91 respondents “indicated they always use oxygen when one crewmember leaves his duty station above 35,000 feet,” according to the survey; 10 percent reported occasional use; 25 percent rarely; and 33 percent never.

Above 41,000 feet under Part 91, the number who always use oxygen was 18 percent; occasionally, less than one percent; 8 percent, rarely; 28 percent, never; and 44 percent responded “not applicable.”

The compliance numbers for Part 121 respondents were higher, with 39 percent reporting always using oxygen when required above 25,000 feet and 48 percent above 41,000 feet.

Part 135 respondents were nearer the Part 91 results, with 21 percent saying they always use supplemental oxygen when only one crewmember is at the controls above 25,000 feet and 18 percent continuously using oxygen when flying above 35,000 feet.

Of 545 pilots who responded to a question about whether they had trained in an altitude chamber, 368 said yes and 177 said no. When asked if the training made them “more likely to use supplemental oxygen after attending altitude chamber training,” 22 percent strongly agreed and 21 percent agreed. The rest were neutral (26 percent), disagree (24 percent) and strongly disagree (7 percent), with one percent indicating “not applicable.”

The results of the survey, according to Shaver, “support the researcher’s hypothesis that there is an attitude toward non-compliance with the supplemental oxygen regulations” and “that Part 91 pilots are the most likely to forego the regulations on supplemental oxygen use.” However, results also reveal “that Part 135 pilots are slightly less likely to use supplemental oxygen than Part 91 pilots.”

A Culture of Non-compliance

Shaver believes there are three reasons why pilots don’t use oxygen as mandated by FAA regulation. The first is comfort and convenience. “The oxygen mask itself is not comfortable, and with some aircraft being capable of 12 or more hours in cruise flight, it would be difficult to wear a mask for that duration. In addition, oxygen masks make both inter-crew and radio communications difficult.”

If pilots were to comply with the regulations, many more aircraft would require oxygen system servicing after every flight, “adding time and expense to the operation.” Operators could be forced to choose between flying at efficient higher altitudes and using more oxygen or flying at lower altitudes and burning much more fuel. Shaver added that some pilots worry that if they use the oxygen for regulatory compliance, they might run out of oxygen in an emergency.

A more important point is related to health, and Shaver quoted an FAA study as follows: “However, prolonged flights at high altitudes using a high concentration of oxygen can produce some symptoms of oxygen poisoning such as infection or bronchial irritation.” Long-range aircraft could thus present an oxygen toxicity issue for pilots, and there is also the problem of mask hygiene and procedures to keep them clean and free of germs.

The results of the survey, Shaver concluded, “point toward the need for a change in FAA regulations regarding supplemental oxygen, or if not a change in regulations, at least a different approach to high-altitude training.” But, he told AIN, “The FAA is kind of hamstrung. It’s almost an impossible regulation to enforce, unless you have someone in the cockpit.”

What makes more sense are the European regulations, which mandate supplemental oxygen use when cabin altitudes climb to dangerous levels. This seems to recognize both that explosive decompression is extremely rare and that the predominant accident scenario where oxygen may help is a slow decompression. “I don’t think [the regulations] are in place to deal with that type of slow decompression,” he said.

A more fundamental question revealed by Shaver’s survey is whether the FAA can revisit regulations written many years ago and repurpose them around real risks instead of assumptions that may no longer be valid?

Which regulation might have helped in the Payne Stewart or other notable slow-decompression accidents: one that mandates oxygen use at high altitudes or one that requires oxygen use when the cabin altitude climbs into the teens? And in any case, Shaver noted, more research needs to be done on whether pilots could survive an explosive decompression above, say, 41,000 feet even if they were wearing the mask as required. “I’d like to know that,” he said.

Whether or not the majority of pilots are complying with the regulations, pilots understand that “their job is to assess risks,” Shaver explained. “If there are that many pilots assessing this particular risk of using supplemental oxygen in flight who feel that the risks aren’t enough to do it, then there is most likely some validity. I don’t think 60 percent of pilots have a cavalier or dangerous attitude.”

But Shaver believes that something needs to be done with the questions that he raised with his survey. People are, after all, still flying many older airplanes developed around the time that oxygen regulations were written.

What might happen is that more aircraft manufacturers will add automatic emergency des-cent systems and that the FAA might make this mandatory for aircraft flying above, say, 45,000 feet. Such a system is already installed on Gulfstream’s GV/ G500/550 and upcoming G650. “If [the FAA] relaxes the use of supplemental oxygen in trying to keep inherent safety,” Shaver said, “then there have to be other capabilities for getting the airplane down. I can see that happening. It would not increase compliance with supplemental oxygen use, but would increase safety overall.”