FAA Mandates Altimeter Upgrades to Dodge New Wireless Signal Interference
Published Date: 1/7/2026
Proposed Rule
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.
Analyzed Economic Effects
6 provisions identified: 1 benefits, 5 costs, 0 mixed.
Immediate retrofit for major air carriers
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 require installing new or upgraded radio altimeters that withstand interference from the 3.98–4.2 GHz band and may require time and money to implement.
Estimated national retrofit cost
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 million).
Two‑year retrofit delay for other aircraft
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 operators a delayed compliance deadline compared with large carriers, but they still must upgrade within the two-year window.
Potential operating limits until compliance
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, including low-visibility flights, until upgraded.
No requirement for aircraft without altimeters
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
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.
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Key Dates
Department and Agencies
Related Federal Register Documents
2026-15585, Requirements for Interference-Tolerant Radio Altimeter Systems
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). This final rule supports the Federal Communications Commission's July 2026 Report and Order that makes 160 megahertz of the Upper C-band available for terrestrial wireless flexible use via a system of competitive bidding. To ensure safe, efficient, and reliable aviation operations in the presence of wireless signals in the C-band, the Federal Aviation Administration is issuing new regulations that 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. These regulations 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 December 30, 2030, which is prior to the date the Federal Communications Commission authorizes the use of the Upper C-band for new wireless services, as stated in its Report and Order. All other aircraft equipped with radio altimeters that are required to comply with part 91, including aircraft operating under parts 125, 133, 135, 136, 137, 194, and all other aircraft operating under part 129 that are not subject to the initial deadline, must comply with the same minimum performance requirements on or before October 31, 2034.
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