The FAA has again revised an alert related to radar altimeters due to the possibility of interference from 5G signals on the adjacent C-band.
New information in the revised alert summarizes the compliance requirements of several airworthiness directives issued earlier this year that apply to all transport- and commuter-category airplanes and helicopters equipped with a radar altimeter, according to AIN. The advanced directives were issued because of a determination that radar altimeters can’t be relied on to perform properly when they are operating in the presence of 5G C-band emissions.
In addition to the previous recommendations, the alert now encourages “all operators to equip their aircraft with 5G C-band tolerant [radar altimeters] as soon as possible.” Such upgraded equipment was not widely available when the alert was originally published. In addition, there continues to be concerns about the “cumulative effects” of interference on associated aircraft systems that rely on radar altimeter inputs, according to AIN.
The revised Safety Alerts for Pilots (SaFo) 21007 notes that those associated systems include windshear detection systems, altitude safety callouts and aural warnings. They also include: autothrottles, reversers, stick pusher/shaker, engine and wing anti-ice systems, autoflight systems, and other equipment intended for maintaining safe flight, particularly during takeoffs, climbs, descents and landings.
By Leslie Stimson, Inside Towers Washington Bureau Chief
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