# 2026-00051: FAA Mandates Altimeter Upgrades to Dodge New Wireless Signal Interference 2026-00051, Requirements for Interference-Tolerant Radio Altimeter Systems, is a Federal Register proposed rule from Transportation Department, Federal Aviation Administration published 2026-01-07, effective Send comments on or before March 9, 2026.; deemed significant under Executive Order 12866 (as of 2026-11-04). - Canonical: https://policyrisk.com/federal-register/2026-00051 - As of: 2026-11-04 - Plain-text twin of the page above; the HTML and this file carry the same facts. ## Facts - Document number: 2026-00051 - Title: Requirements for Interference-Tolerant Radio Altimeter Systems - Type: Proposed Rule - Agencies: Transportation Department; Federal Aviation Administration - Citation: 91 FR 459 - Published: 2026-01-07 - Effective: Send comments on or before March 9, 2026. - Comments close: not stated - Significant: yes (OIRA_API) - Touches household money: no - Regulation identifier numbers: 2120-AM21 - Last updated: 2026-11-04 ## In one line FAA Mandates Altimeter Upgrades to Dodge New Wireless Signal Interference ## Summary The FAA is proposing new rules to make sure all aircraft radio altimeters can handle interference from new wireless signals in the Upper C-band. This affects planes with 30+ seats or heavy payloads first, with others following two years later. These changes help keep flights safe as new wireless services roll out, and aircraft owners should prepare for updates that might cost time and money. ## Abstract 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. ## Effects PRIA read - Immediate retrofit for major air carriers: cost, high. If you operate aircraft under 14 CFR part 121 or operate under part 129 with 30 or more passenger seats or a payload over 7,500 pounds, your radio altimeter must meet new minimum interference-tolerance standards by the date the FCC authorizes wireless service in the Upper C-band. The rule would req… - Two‑year retrofit delay for other aircraft: cost, medium. All other aircraft operating under part 91 in the 48 contiguous United States and the District of Columbia that are equipped with radio altimeters must meet the proposed minimum performance requirements two years after the FCC authorizes wireless service in the Upper C-band. That gives these operat… - No requirement for aircraft without altimeters: benefit, low. Aircraft that are not currently equipped with a radio altimeter would not need to install or upgrade a radio altimeter under this proposed rule. If your aircraft lacks an RA now, you would not be required to install one because of this rule. - FAA's expected retrofit timeline: cost, low. FAA expects the initial radio altimeter performance deadline will be achievable between 2029 and 2032. That is the timeframe FAA uses to plan equipment development and retrofits for the required interference-tolerant radio altimeters. - Estimated national retrofit cost: cost, high. FAA estimates the total undiscounted cost to retrofit radio altimeters is $4.494 billion, or $424 million annualized at a 7 percent discount rate over 20 years. The table in the proposal breaks costs out by operational part (for example, Part 91 undiscounted cost $1,589 million; Part 121 $1,363 mil… - Potential operating limits until compliance: cost, medium. FAA would supersede current airworthiness directives and could impose operating limitations on aircraft with radio altimeters that do not meet the proposed performance requirements until those RAs are replaced. That means non-compliant aircraft could face restrictions that limit operations, includi… ## Related documents - [2026-15585](https://policyrisk.com/federal-register/2026-15585): Requirements for Interference-Tolerant Radio Altimeter Systems, 2026-07-31 - [2026-13440](https://policyrisk.com/federal-register/2026-13440): Enabling Supersonic Overland Flight, 2026-07-02 - [2026-13126](https://policyrisk.com/federal-register/2026-13126): Designation-Restrict the Operation of Unmanned Aircraft in Close Proximity to a Fixed Site Facility; Extension of Comment Period, 2026-06-30 - [2026-08943](https://policyrisk.com/federal-register/2026-08943): Designation-Restrict the Operation of Unmanned Aircraft in Close Proximity to a Fixed Site Facility, 2026-05-06 - [2025-04846](https://policyrisk.com/federal-register/2025-04846): Extension of the Prohibition Against Certain Flights in the Territory and Airspace of Libya, 2025-03-20 - [2025-03853](https://policyrisk.com/federal-register/2025-03853): Enforcement Policy Regarding “Drug and Alcohol Testing of Certificated Repair Station Employees Located Outside of the United States; Corre…, 2025-03-11 ## Sources - [2026-00051 on federalregister.gov](https://www.federalregister.gov/documents/2026/01/07/2026-00051/requirements-for-interference-tolerant-radio-altimeter-systems) - [2026-00051 as published (PDF)](https://www.govinfo.gov/content/pkg/FR-2026-01-07/pdf/2026-00051.pdf) ## Related - [Previous: 2026-00048, Safety Zone; West of Cyril E. King Airport, St. Thomas, VI](https://policyrisk.com/federal-register/2026-00048) - [Next: 2026-00084, Hazardous and Solid Waste Management System: Disposal of Coal Combustion Residu…](https://policyrisk.com/federal-register/2026-00084) - [All Federal Register documents](https://policyrisk.com/federal-register) Source: PRIA, https://policyrisk.com/federal-register/2026-00051 (as of 2026-11-04).