Federal Register #2026-13162

FAA Mandates Radio Altimeter Modifications for 5G Interference Mitigation in Airplanes

The Federal Aviation Administration (FAA), under the Department of Transportation, is mandating new airworthiness directives for all transport and commuter category airplanes equipped with radio altimeters due to 5G wireless broadband interference risks in the 3.7-3.98 GHz band, especially in Canadian airspace. - Government Buyer: - Federal Aviation Administration (FAA), Department of Transportation - Aircraft Certification Service, Compliance & Airworthiness Division - Affected Aircraft: - All transport and commuter category airplanes with radio altimeters, including Boeing 737 models - Products/Services Requested: - Revision of Airplane Flight Manuals (AFM) to prohibit certain operations requiring radio altimeter data in Canadian airspace - Modification of non-tolerant airplanes to achieve radio altimeter tolerance, via: - Replacement of radio altimeter units (estimated 180 airplanes) - Installation of externally mounted radio altimeter filters (estimated 820 airplanes) - Quantities: - 180 airplanes estimated for radio altimeter replacement - 820 airplanes estimated for filter installation - 1,000 airplanes estimated for AFM revision - Unique/Notable Requirements: - No specific OEMs or part numbers are specified; directive applies to all affected aircraft regardless of manufacturer - Compliance is required before further flight in Canadian airspace after the effective date - Estimated total modification cost up to $50 million - Directive is an interim action and may be updated based on future 5G interference or regulatory changes - Impacted Systems: - Terrain Awareness and Warning System (TAWS), Traffic Collision Avoidance System (TCAS), and windshear warning/guidance systems, all reliant on accurate radio altimeter data

Description

The FAA is adopting a new airworthiness directive (AD) for all transport and commuter category airplanes equipped with a radio (radar) altimeter. This AD addresses interference issues caused by wireless broadband operations in the 3.7-3.98 GHz frequency band (5G Lower C-Band) while operating in Canadian airspace. It requires revising the existing airplane flight manual (AFM) to incorporate limitations prohibiting certain operations requiring radio altimeter data in Canadian airspace. The directive aims to mitigate unsafe conditions due to radio altimeter interference and enhance flight safety.

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