The Federal Aviation Administration has issued an airworthiness directive (AD) for Boeing aircraft stemming from the use of 5G wireless towers. According to the AD released Tuesday, the radio altimeters on Boeing 777s and 747-8s can “experience interference” from 5G C-band wireless towers.
The AD is slated to be published in the Federal Register on January 27.
According to the document, the 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-C band).”
Why This Matters
The radio altimeter provides the pilot with information about how high the aircraft is above terrain. In instrument meteorological conditions, the pilot cannot see the terrain out the window and must rely on the instruments, such as an altimeter, to determine the aircraft’s position.
Faulty information could potentially put the aircraft dangerously low and may compromise other aircraft systems even in good weather, the AD continues. “A recent determination that this interference may affect multiple airplane systems using radio altimeter data, including the pitch control laws, including those that provide tail strike protections regardless of the approach type or weather,” according to the FAA documentation.
The FAA proposes that Boeing address this AD by revising the limitations of the existing airplane flight manual to incorporate limitations prohibiting dispatching or releasing to an airport, and approaches or landings on runways, when in the presence of 5G C-band interference as identified by notices to air missions.
5G networks use a set of radio waves called “C band spectrum.” The purpose of 5G is to provide for faster internet operations, however, the FAA and other members of the aviation industry have expressed concerns that 5G may interfere with radio altimeters of aircraft on approach to certain airports and, therefore, have a negative impact on flight safety.