The US Federal Aviation Administration (FAA) proposed a directive which would mandate passenger and cargo aircraft have C-Band-tolerant altimeters or approved filters installed by early 2024 as a path forward for allowing 5G services to safely coexist with the aviation industry.

The airworthiness directive (AD) is similar to one implemented in December 2021 which prohibited flight operations around C-Band wireless transmitters unless the FAA approved them.

An FAA representative told Mobile World Live the AD would be open for public comment for 30 days. The new rules would go into effect on 24 February 2024.

In a statement, the FAA described the proposal as a collaboration between wireless companies, aviation stakeholders and other federal agencies including the Federal Communications Commission (FCC) to “enable the wireless companies to achieve full use of their networks while maintaining public safety”.

The proposal also requires aviation operators to revise their flight manuals to prohibit low-visibility landings after 30 June unless the retrofits have been completed.

Verizon and AT&T delayed the launch of 5G services on C-Band spectrum until January 2022 after the aviation industry expressed concern about interference with cockpit safety systems.

The operators later agreed to further delay some of their C-Band usage near airports until July 2023 to give the aviation industry more time to retrofit aircraft

In October 2022, acting FAA administrator Billy Nolen called for the FCC to expand exclusion zones AT&T and Verizon implemented around airports to 19 smaller mobile operators and other spectrum holders.

Opposition
Trade organisation Airlines for America (A4A) stated while it supported moving forward on safety measures and mitigation efforts related to the use of C-Band, the compliance deadline for changing radio altimeters needed to be feasible .

“A4A member carriers are working diligently to ensure fleets are equipped with compliant radio altimeters, but global supply chains continue to lag behind current demand,” it stated.