In a Notice of Proposed Rulemaking (NPRM) published on September 24, the FAA proposes to amend regulations for pilot use of oxygen in parts 91 and 135. The proposal, Flight Operations: Pilot requirements; Use of oxygen, increases the altitudes above which pilot use of oxygen is required.
Current part 135 regulations require oxygen use above Flight Level (FL) 350 when more than one pilot is present. When a pilot leaves their station, the remaining pilot must use their oxygen mask until the other pilot returns above FL250 under existing rules.
The NPRM proposes to revise those altitudes to FL410 when more than one pilot is present and to FL350 when a single pilot is at the controls.
Two key aspects of the proposed FAA rule:
- Two pilots at the controls: Whenever a pressurized aircraft is operated at altitudes above FL410, at least one pilot at the controls shall wear, secured and sealed, an oxygen mask required by regulation.
- One pilot at the controls: Whenever only one pilot is at the controls of an aircraft when operating above FL350, that pilot shall put on and use an approved oxygen mask.
The rulemaking is largely the result of a NATA-supported provision in the FAA Reauthorization Act of 2024 calling on the agency to adopt the change after a review of available data. In addition to the changes for part 135 operations stipulated by Congress, corresponding changes are also proposed for part 91 operations. FAA’s review notes that pressurization incidents in both parts 91 and 135 are rare.
Implementation of the NPRM would establish a more consistent regulatory policy across parts 91, 121 and 135 operations. (Part 121 regulations have had a similar provision for several years.) The amendment would alleviate an unnecessary operational burden and result in estimated overall cost savings of $4.7 to $18.6 million annually.
NATA is conducting a detailed review of the NPRM to inform association comments. Operators impacted by these changes are also encouraged to review the NPRM and comment. Comments will be accepted through November 23, 2026.