Safety Recommendation A-22-001

-From Bryan Bedofrd, Administrator: The Federal Aviation Administration (FAA) coordinated with the ASTM Committee F37 on Light Sport Aircraft, which is developing standards for Light Sport Airplanes under the expanded scope of changes found in the 2025 Modernization of Special Airworthiness Certification (MOSAIC) Rule, effective October 22, 2025. The committee, made up of members from industry and global regulators, supported the Board’s recommendation and balloted a standard that requires active CO detectors, which received universal support.

We also coordinated with the ASTM Committee F44 on General Aviation Aircraft, which initiated the development of a standard for CO detectors on type certificated part 23 airplanes. During this coordination, we found that nearly all newly delivered part 23 airplanes are equipped with CO detectors as standard equipment. FAA discussions with avionics system suppliers indicated that CO detectors are included in almost all retrofits of part 23 airplanes that involve installing glass displays.

The FAA currently does not plan to mandate CO detectors by rulemaking, as such an action would prevent the installation of CO detectors under FAA Policy Statement PS-AIR-21.8-1602, Approval of Non-Required Safety Enhancing Equipment (NORSEE). It would also eliminate the option of using commercial off the shelf (COTS) CO detectors, CO detectors integrated into headsets, and other options. A study conducted by the United Kingdom Civil Aviation Authority found COTS CO detectors to be effective, and the FAA found many service reports in the United States fleet where these devices alerted the pilot to high CO levels caused by exhaust leaks. The NORSEE Policy Statement can be found at:

https://drs.faa.gov/browse/excelExternalWindow/1790B02F1833357486257F9200592110.0001

I believe the FAA has effectively addressed the intent of Safety Recommendation A-22-1, and we plan no further action on this safety recommendation.

We note that you agree that CO detectors provide an additional layer of protection for general aviation aircraft occupants, and we are encouraged that you are considering the recommended requirement. We also note that the FAA has previously issued rulemaking and guidance on maintaining and inspecting CO detectors and, in 2016, issued Policy Statement PS-AIR-21.8-1602, “Approval of Non-Required Safety Enhancing Equipment (NORSEE).” The statement identifies CO detectors as one type of equipment that may be considered NORSEE, and includes guidance for companies seeking approval of CO detectors.

We point out, however, that these actions were completed prior to the issuance of this recommendation and, despite this information being available, we continue to investigate accidents involving aircraft without CO detectors. Therefore, we urge you to require CO detectors, as recommended. Pending such a requirement, Safety Recommendation A-22-1 is classified OPEN-- ACCEPTABLE RESPONSE.

-From Polly Trottenberg, Acting Administrator: The Federal Aviation Administration (FAA) agrees with the Board that CO detectors provide an additional layer of protection for those who fly on general aviation aircraft. In response to previous accidents and incidents on this subject, we have issued rulemaking and provided guidance on maintenance and inspection practices for the use of CO detectors to enhance public awareness. These include: • Airworthiness Directive 2008-26-05, Bombardier-Rotax GmbH 914 F Series Reciprocating Engines, published December 22, 2008 (73 FR 78173).

• DOT/FAA/AR-09/49, Detection and Prevention of Carbon Monoxide Exposure in General Aviation Aircraft, published October 2009, which is available at the following website: https://www.tc.faa.gov/its/worldpac/techrpt/ar0949.pdf

• Special Airworthiness Information Bulletin CE-10-19 R1, Engine Exhaust and Carbon Monoxide Detectors, published March 17, 2010, which is available at the following website: drs.faa.gov • Educational material from the FAA Office of Aerospace Medicine, Carbon Dioxide, A Deadly Menace, which is available at the following website: https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/cobroforweb.pdf

Additionally, on March 31, 2016, the FAA issued Policy Statement PS-AIR-21.8-1602, Approval of Non-Required Safety Enhancing Equipment (NORSEE). This policy provides procedures for issuing a design and production approval pursuant to Title 14, Code of Federal Regulations § 21.8(d), Approval of Articles, for equipment designated as NORSEE. This policy was written to encourage and enable voluntary safety enhancements. It expressly identifies CO detectors as one type of equipment that may be considered NORSEE under the policy, and provides a clear path to design and production approval for companies seeking approval of CO detectors and other technologies.

We note that you are reviewing our aviation investigation report and determining how to respond to this recommendation. Pending the completion of your review and a plan for addressing this recommendation, Safety Recommendation A-22-1 remains classified OPEN-- AWAIT RESPONSE.

-From Billy Nolen, Acting Administrator: The Federal Aviation Administration is reviewing the Board’s report, “Require Carbon Monoxide Detectors in Certain General Aviation Aircraft, AIR-22-01,” and determining an appropriate action plan.

I will keep the Board informed of our progress on this recommendation and anticipate providing an update by March 31, 2023.

The attached letter from the NTSB Chair provides information about the NTSB’s December 20, 2021, report Require Carbon Monoxide Detectors in Certain General Aviation Aircraft, NTSB/AIR-22/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.

The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendations by number (for example, A-22-1). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.

This letter provides information about the National Transportation Safety Board’s (NTSB) December 20, 2021, report Require Carbon Monoxide Detectors in Certain General Aviation Aircraft, NTSB/AIR-22/01. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.

As a result of this investigation, we identified the following safety issues:

• Further serious and fatal accidents due to pilot CO poisoning • Continued lack of Federal Aviation Administration (FAA) requirement for carbon monoxide (CO) detectors in general aviation aircraft

Accordingly, the NTSB makes the following safety recommendation to the FAA.

• Require that all enclosed-cabin aircraft with reciprocating engines be equipped with a functional CO detector that complies with an aviation-specific minimum performance standard with active aural or visual alerting.