Transportation Department, Federal Aviation Administration
In July 2025, President Trump signed the One Big Beautiful Bill Act. Section 40002 of that law re-institutes the Federal Communications Commission's general auction authority and specifically directs the Commission to complete a system of competitive bidding for not less than 100 megahertz in the 3.98-4.2 gigahertz band (Upper C- band). To ensure safe, efficient, and reliable aviation operations in the presence of wireless signals in the Upper C-band, the Federal Aviation Administration is proposing new regulations that would require all radio altimeters to meet specific minimum performance requirements. These new radio altimeters must withstand interference from wireless signals in neighboring spectrum bands and continue to provide accurate altitude readings to both pilots and integrated aircraft safety systems. The minimum interference tolerance requirements proposed in this rule reflect the best achievable interference rejection using current technology without compromising radio altimeter system performance. These regulations would require all aircraft equipped with radio altimeters operating under part 121 and those aircraft with radio altimeters operating under part 129 with 30 or more passenger seats or a payload capacity of more than 7,500 pounds to comply with the minimum performance requirements by the date the Federal Communications Commission authorizes wireless services in the Upper C-band. All other aircraft equipped with radio altimeters would be required to comply with the same minimum performance requirements two years later. This proposed rule is a companion to the Federal Communications Commission's NPRM to expand the ecosystem for next-generation wireless services in the 3.7-4.2 gigahertz band by making as much as 180, and at least 100, megahertz of the Upper C-band available for terrestrial wireless flexible use via a system of competitive bidding.
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 Parts 91, 121, and 129 [Docket No.: FAA-2025-5666; Notice No. 26-02] RIN 2120-AM21 AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: In July 2025, President Trump signed the One Big Beautiful Bill Act. Section 40002 of that law re-institutes the Federal Communications Commission's general auction authority and specifically directs the Commission to complete a system of competitive bidding for not less than 100 megahertz in the 3.98-4.2 gigahertz band (Upper C-band). To ensure safe, efficient, and reliable aviation operations in the presence of wireless signals in the Upper C-band, the Federal Aviation Administration is proposing new regulations that would require all radio altimeters to meet specific minimum performance requirements. These new radio altimeters must withstand interference from wireless signals in neighboring spectrum bands and continue to provide accurate altitude readings to both pilots and integrated aircraft safety systems. The minimum interference tolerance requirements proposed in this rule reflect the best achievable interference rejection using current technology without compromising radio altimeter system performance. These regulations would require all aircraft equipped with radio altimeters operating under part 121 and those aircraft with radio altimeters operating under part 129 with 30 or more p…
Citation: 91 FR 459
