The FAA appears to be shifting much of the burden related to information generation and gathering aimed at resolving the continuing quagmire over 5G C-band radio altimeter interference to avionics and aircraft OEMs, aircraft operators, and a civilian contractor to the agency. In a special airworthiness information bulletin (SAIB) issued yesterday, the FAA requested that manufacturers of radio altimeters and aircraft, as well as operators, continue to voluntarily provide “specific information” related to those altimeters’ design, functionality, and usage; continue to test the equipment in cooperation with federal authorities; and report results to both civil aviation authorities and spectrum regulators.
The FAA said it is continuing to collaborate with the Federal Communications Commission and the National Telecommunications and Information Administration on the issue as it assesses options beyond its previous airworthiness directives (ADs), which prohibit select aircraft operations in the presence of 5G cellphone tower interference as of July 1, 2023, and ban all Part 121 (airline) operations after Feb. 1, 2024, unless performed with a radio altimeter-tolerant airplane. The FAA called the requirements interim actions pending the development of a “Technical Standard Order for radio altimeters...that meets international minimum operational performance standards.”
The information requested in the SAIB is detailed, potentially voluminous, and in many cases likely proprietary. The FAA further asks that all retrofit plans and details be forwarded to the Mitre Corporation—the FAA’s chief civilian technical contractor for collection, aggregation, and de-identification. It places a heavy burden on avionics and aircraft manufacturers in particular for equipment and procedure testing and analysis, updating aircraft flight manuals, reporting anomalies, and developing retrofit plans. Part 121 operators are requested to incorporate the potential for 5G C-band interference into their safety management systems and flight planning and coordinate information on interference with avionics and aircraft manufacturers.
The SAIB also notes that “operators should consider the potential loss of pilot trust in dependent aircraft safety systems in the assessment of existing, and the development of new, crew procedures.” Pilots are encouraged to report all radio altimeter anomalies to air traffic control and submit detailed incident reports to the FAA.