2026-00051Proposed Rule

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

Published Date
Comments Due
1/7/2026
3/9/2026

Department and Agencies

Department
Independent Agency
Agency
Transportation Department
Federal Aviation Administration
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