The U.S. Federal Aviation Administration (FAA) is expected to publish a final rule on July 24 requiring mandatory upgrades to aircraft radio altimeters, according to Aviation Week.

The new regulation is linked to a decision by the Federal Communications Commission (FCC) to release an additional portion of the upper C-band spectrum for future wireless communication services. On July 22, the FCC approved a plan to auction a total of 160 MHz of spectrum by mid-2027.

New wireless services in that frequency range are scheduled to begin operating in December 2030 in the 75 largest U.S. markets, while deployment in the rest of the country is expected to start in July 2031.

The FAA is expected to align aircraft compliance deadlines with that schedule. Airlines operating scheduled commercial services will likely be required to complete radio altimeter upgrades by the end of 2030, before the new systems become operational. Other affected aircraft are expected to receive an additional compliance period of approximately two years.

The FAA published its draft rule in January, proposing a two-phase modernization program. The first phase would apply to commercial operators, while owners and operators of other aircraft covered by the regulation would receive a longer transition period.

At the time, the FAA assumed that the new telecommunications services could be introduced between 2029 and 2032 and said the final deadlines would be adjusted to match the FCC’s approved schedule. Aviation and telecommunications industry representatives have since concluded that the end of 2030 is an achievable target for upgrading commercial fleets.

Rebates and other financial incentives are also planned to accelerate the replacement or modification of existing radio altimeters. Funding for the program is expected to come from proceeds generated by the spectrum auction.

The FAA confirmed that the final rule retains the two-phase implementation plan but did not disclose precise compliance deadlines for individual aircraft categories ahead of its official publication.

Radio altimeters measure an aircraft’s height above the ground and play an important role in terrain-warning systems, automatic landing functions and other systems used during the final phases of flight. The aviation industry has previously warned that powerful 5G signals operating in nearby frequency bands could interfere with older or insufficiently protected equipment.

The new requirements are intended to remove some of the uncertainty that accompanied the initial rollout of 5G networks in the United States earlier in the decade, when some airlines were forced to temporarily modify operating procedures, cancel flights or restrict the use of certain aircraft types at individual airports.

According to the FAA, aligning technical requirements and compliance deadlines should provide telecommunications operators with the certainty needed to participate in the future spectrum auction, while the financial incentive program will help the aviation industry install next-generation radio altimeters on time. This could allow commercial aircraft to receive more advanced equipment several years earlier than would otherwise have been possible without regulatory and financial support.