Airworthiness Directives; The Boeing Company Airplanes

The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 707, 717, and 727 airplanes; Model DC-8, DC-9, and DC-10 airplanes; Model MD-10 and MD-11 airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87), and MD-88 airplanes; and Model MD 90-30 airplanes. This AD was prompted by the determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G Lower C- Band) while operating in Canadian airspace, and the determination that during approach, landings, and go-arounds, as a result of this interference, certain airplane systems may not properly function, resulting in increased flightcrew workload while on approach with the flight director, autothrottle, or autopilot engaged, which could result in reduced ability of the flightcrew to maintain safe flight and landing of the airplane. This AD requires revising the existing airplane flight manual (AFM) to incorporate limitations prohibiting certain operations requiring radio altimeter data when operating in Canadian airspace. The FAA is issuing this AD to address the unsafe condition on these products.