The FAA has proposed raising the altitudes at which pilots must wear oxygen masks on pressurised aircraft. The notice of proposed rulemaking landed in the Federal Register on 24 September 2026. Comments close on 23 November 2026.

For two-pilot Part 135 work, the mask threshold would move from FL350 to FL410. When only one pilot is at the controls on a Part 135 flight, the wear altitude would rise from FL250 to FL350. Part 91 would go further. Crews with qualifying quick-donning masks would not have to wear a mask solely because of altitude, at any certified flight level. Without those masks, one Part 91 pilot would still wear oxygen above FL350.

NBAA framed the proposal as the product of years of advocacy and of Section 834 of the FAA Reauthorization Act of 2024. That statute directed the agency to publish an NPRM on the Part 135 oxygen rules. The association said altitude-based mask thresholds set in the 1950s and 1960s no longer match modern pressurisation and warning systems. Current US rules sit tighter than ICAO standards, which require quick-donning masks to be available above FL250 but do not force continuous wear at a fixed flight level.

For charter and on-demand operators, the cost sits in oxygen burn and servicing, not in how the flight deck looks. The FAA put the affected fleet at roughly 4.7 million Part 91 and Part 135 turbojet and multiengine turboprop operations. It estimates that each percentage point reduction in oxygen servicing could save operators about USD 4.7 million to USD 18.6 million a year. That range uses refill fees of USD 100 to USD 400 per service. Exact fleet-level savings remain uncertain because the agency lacks firm data on how often tanks are topped up today.

Time of useful consciousness above FL350 is 30 to 60 seconds after a gradual decompression, and 15 to 30 seconds after a rapid one, according to the table in the NPRM. The FAA reviewed about 200 pressurisation reports over more than 20 million flight hours above FL250 between January 2015 and May 2025. Most events were gradual. Four of the 200 were classed as rapid or explosive. Operators remain free to keep stricter internal standards than the federal minimum.

Part 91 would loosen more than Part 135. Commercial on-demand work would stay tighter than private flying, even as both regimes ease relative to today. Fleet managers should treat the NPRM as a planning document, not a finished rule. Training manuals and oxygen contracts will need a look if the text becomes final. Single-pilot Part 135 types, and missions where one pilot leaves the seat, would still face a FL350 wear requirement under the proposal.

Two-crew Part 135 jets would gain the FL410 threshold that many operators have sought through exemptions. The FAA has largely denied those petitions since the mid-1980s, saying a rule change, not a one-off waiver, was the proper path.

AIN reported the same NPRM on 24 September. It noted that Part 91 pilots would no longer have to wear masks solely for altitude, while Part 135 rules would allow higher levels before continuous wear. That independent trade coverage matches the Federal Register thresholds.

The docket is open through 23 November. NBAA said it will coordinate member comments. Operators who want clearer language on single-pilot Part 135 applicability, or on what counts as a qualifying quick-donning mask, should file before the window closes.

Goodall Aviation is watching the NPRM for how it changes the cost and comfort of high-altitude ACMI and wet-lease placements. When we arrange capacity for operators, oxygen servicing and crew practice sit inside the operating economics. A higher threshold would simplify some US Part 135 packages. It would not change the need for solid pressurisation procedures. Operators can reach the desk if they want that read against a specific type.

Sources: federalregister.gov, nbaa.org, ainonline.com