YEARS OF TESTING LEAD TO DUAL-AGENCY REGULATORY ACTION ON 5G AND ALTIMETERS

The Federal Aviation Administration has announced it will issue a final rule on Friday 24 July 2026 requiring all radio altimeters operating on aircraft in the United States to meet next-generation performance requirements that prevent interference from 5G signals in neighbouring spectrum bands. The announcement, made on Wednesday 23 July, is coordinated with the Federal Communications Commission’s Report and Order — adopted on 23 July — governing new 5G spectrum band auctions. The dual-agency action represents the conclusion of an extensive joint process that has included years of FAA-led testing, technical analysis and agency coordination, and follows the FAA’s proposed rule issued for public comment in January 2026.

Radio altimeters are among the most safety-critical instruments on commercial and general aviation aircraft. They measure an aircraft’s height above the terrain and obstacles below, providing accurate altitude readings to pilots and directly feeding the data inputs to aircraft safety systems, including those governing Instrument Landing System approaches during low-visibility conditions. The concern that 5G signals in neighbouring spectrum bands could cause inaccurate altimeter readings — and thereby compromise Category II and Category III ILS approach capabilities — has driven the regulatory process. The FAA said it was confident, as a result of the coordination and technical analysis completed, that aviation could safely coexist with expanded wireless access.

WHAT THE FCC FRAMEWORK PROVIDES AND HOW THE TWO RULES ALIGN

The FCC’s Report and Order contains several specific safeguards designed to protect altimeter frequencies in the new 5G auction bands. These include: limiting the power of the auctioned 5G signals to levels the FAA has determined are safe for aviation; protecting the altimeter frequency band with a buffer band between it and the auctioned spectrum; limiting the height of 5G transmission towers in the new band; and ensuring the functionality of key altimeter-based alerting systems including Terrain Avoidance Warning Systems. The FAA rule has been designed in alignment with this framework, providing technical and schedule certainty to potential 5G auction bidders and establishing the upgrade timeline to which the FCC’s radio-altimeter rebate programme will provide financial incentives for compliance.

TWO DEADLINES: SCHEDULED AIRLINES FIRST, ALL AIRCRAFT SECOND

The FAA final rule establishes two separate compliance deadlines. The first applies to scheduled air carriers — those operating commercial passenger services — who must be able to continue operations without disruption during low-visibility conditions, meaning their aircraft must be equipped with next-generation altimeters by the earlier deadline. The second deadline applies to all other aircraft to maintain the broader safety enhancements of altimeter systems across all operational scenarios. The FAA said the structure of the rule and the FCC’s rebate programme would result in commercial aircraft equipping with next-generation technology several years earlier than would otherwise have been feasible, accelerating the safety improvement across the fleet while providing the regulatory certainty the 5G auction market requires.