FAA proposes relaxing oxygen mask rules for Part 135 and 91 operations

The FAA has proposed a new rule that would relax oxygen mask requirements for Part 135 charter operations and Part 91 general aviation, according to Flying Magazine. The agency argues that the changes would save operators millions of dollars annually without adversely affecting safety.

Flying Magazine reports that the FAA published a notice of proposed rulemaking last week. Comments on the proposal are due November 23.

Changes to Part 135 and Part 91 requirements

For Part 135 operations, the proposed rule would raise the two-pilot quick-donning oxygen mask threshold from FL350 to FL410. It would also raise the single-pilot Part 135 mask threshold from FL250 to FL350.

For Part 91 pilots of pressurized aircraft, the FAA would permit flying at any certified altitude without a mask if quick-donning masks are available. Flying Magazine defines a quick-donning mask as capable of being placed on the face with one hand within five seconds, without disturbing eyeglasses, delaying emergency duties, or disrupting normal communications.

Safety justification and cost savings

The FAA said its existing regulations are stricter than International Civil Aviation Organization standards. It justified the rulemaking due to improvements in pressurization and warning systems in modern aircraft, as well as the low rate of pressurization failures at high altitude.

Flying Magazine reports that the agency reviewed over 20 million flight hours flown above FL250 by Part 91 and Part 135 operators and found only 200 instances of decompression events, with only a quarter of them above FL410.

According to the proposal, the changes would reduce regulatory and economic burdens on Part 91 and Part 135 fleet operators to the tune of $4.7 million to $18.6 million annually for every 1 percent reduction in applicable servicing requirements. Flying Magazine reports that oxygen servicing costs are between $100 and $400 per fill.

Section 834 of the FAA Reauthorization Act of 2024 directed the agency to consider whether to revise oxygen mask requirements for pilots aboard pressurized aircraft operating under Part 135 if the aircraft is flying below FL410.