Airworthiness Directives; Transport and Commuter Category Airplanes

FAA / Federal Register · 2023-11371

The FAA is superseding Airworthiness Directive (AD) 2021-23- 12, which applied to all transport and commuter category airplanes equipped with a radio (also known as radar) altimeter. AD 2021-23-12 required revising the limitations section of the existing airplane/ aircraft flight manual (AFM) to incorporate limitations prohibiting certain operations requiring radio altimeter data when in the presence of 5G C-Band interference as identified by Notices to Air Missions (NOTAMs). Since the FAA issued AD 2021-23-12, the FAA determined that additional limitations are needed due to the continued deployment of new 5G C-Band stations whose signals are expected to cover most of the contiguous United States at transmission frequencies between 3.7-3.98 GHz. For certain airplanes, this AD requires revising the limitations section of the existing AFM to incorporate limitations prohibiting certain operations requiring radio altimeter data, due to the presence of 5G C-Band interference. This AD also requires modifying certain airplanes to allow safe operations in the U.S. 5G C-Band radio frequency environment. The FAA is issuing this AD to address the unsafe condition on these products.