Transportation Department, Federal Aviation Administration
The FAA proposes to adopt a new airworthiness directive (AD) for all helicopters equipped with a radio (also known as radar) altimeter. This proposed AD was prompted by the determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7 to 3.98 GHz frequency band (5G Lower C-Band) while operating in Canadian airspace. This proposed AD would require revising the existing rotorcraft flight manual (RFM) for the helicopter to incorporate limitations prohibiting certain operations requiring radio altimeter data when operating within Canadian airspace. The FAA is proposing this AD to address the unsafe condition on these products.
Document Headings Document headings vary by document type but may contain the following: the agency or agencies that issued and signed a document the number of the CFR title and the number of each part the document amends, proposes to amend, or is directly related to the agency docket number / agency internal file number the RIN which identifies each regulatory action listed in the Unified Agenda of Federal Regulatory and Deregulatory Actions See the Document Drafting Handbook for more details. Department of Transportation Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA-2026-11799; Project Identifier MCAI-2026-00594-R] RIN 2120-AA64 AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). ( printed page 64310) SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) for all helicopters equipped with a radio (also known as radar) altimeter. This proposed AD was prompted by the determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7 to 3.98 GHz frequency band (5G Lower C-Band) while operating in Canadian airspace. This proposed AD would require revising the existing rotorcraft flight manual (RFM) for the helicopter to incorporate limitations prohibiting certain operations requiring radio altimeter data when operating within Canadian airspace. The FAA is proposing this AD to address the unsafe condition on these products. DATES: The FAA must receive comments on this proposed AD by November 23, 2026. ADDRESSES: You may send comments, using the procedures found in 14 CFR 11.43 and 11.45 , by any of the following methods: Federal eRulemaking Portal: Go to regulations.gov. Follow the instructions for submitting comments. Fax: 202-493-2251. Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590…
Citation: 91 FR 64309
