Comments are due Friday, February 10, to FAA proposed requirements “to help foster coexistence between 5G operations in the C-band and aircraft relying on radio altimeters.” The proposal is an update to an airworthiness directive concerning the coexistence of telecom licensees of C-band spectrum (3.7-4.2 GHz) and radio altimeters.
In a Notice of Proposed Rulemaking, the FAA proposes interference tolerance requirements for radio altimeters and requirements that all transport and commuter aircraft operating under its rules meet power spectral density requirements to operate in the contiguous U.S. after February 2, 2024. The FAA says it’s determined “that radio altimeter tolerant airplanes will not experience unsafe conditions at any airport identified by the FAA as a 5G market.” It’s also decided that any 5G C-band provider that “maintains the mitigated actions, which are based on the power levels to which Verizon and AT&T previously agreed, will not have an effect on the safety of transport and commuter airplanes with radio altimeters that meet the interference tolerance requirements.”
This airworthiness directive supersedes 2021–23–12, according to a Federal Register notice. The FAA found that “additional limitations are needed due to the continued deployment of new 5G C-band base stations whose signals are expected to cover most of the contiguous United States at transmission frequencies between 3.7– 3.98 GHz. This proposed [directive] would also require modifying certain airplanes to allow safe operations in the United States 5G C-band radio frequency environment. The FAA is issuing this airworthiness directive to address the unsafe condition on these products.”
The FAA says it will assess changes in the agreed-upon power levels. Public comments on the FAA’s proposals are due February 10 via regulations.gov. Reference Docket No. FAA–2022–1647; Project Identifier AD–2022–01379–T.
By Leslie Stimson, Inside Towers Washington Bureau Chief
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