Following the rollout of C-band 5G across the US, the Federal Aviation Administration (FAA) has issued a new Airworthiness Directive (AD) for Boeing 737 aircraft.
In its advisory, the government agency warned that C-band 5G transmissions could potentially interfere with landing operations at a small number of airports for most Boeing 737s.
However, this new AD does not apply to landings at airports where C-band 5G hasn't been deployed yet and at airports where the FAA has determined that aircraft radio altimeters are “safe and reliable in the 5G C-band environment”.
Back in January, the FAA gave the go ahead for all 737 models to land at airports when using radio altimeters in low-visibility conditions if C-band 5G towers are present nearby. Now though, the US aviation watchdog has reversed course as radio altimeters cannot be relied upon to perform their indented function in areas with 5G interference and because attempts to deal with this interference, could put additional pressure on aircraft personnel.
Boeing 737 aircraft and 5G interference
The reason the FAA issued its latest AD is due to the fact that several of the systems found on Boeing's 737 aircraft rely on the radio altimeter to function properly. These include the autothrottle, ground proximity warning, thrust reversers and Traffic Collision Avoidance System.
This new directive affects around 2,442 aircraft in the US alone and 8,342 worldwide and could lead to serious disruptions for air travelers.
While Boeing 737 models -100, -200, -200C, -300, -400, -500, -600, -700, 0700C, -800, -900 and -900ER are covered under the latest AD, Model 737-200 and -200C are not as these aircraft are equipped with an SP-77 flight control system that does not have any of the autoland and flare modes that could be affected by 5G signals.
Instead of naming the affected airports, the FAA plans to issue Notices to Air Missions (NOTAMS) where an aircraft's radio altimeter is unreliable due to C-Band 5G interference. Previously the agency identified a total of 87 airports with low-visibility approaches that require pilots to use an altimeter check during landing.
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Via The Register
