Story ID: 
FAA Revises Safety Alert on 5G Interference
By: Gordon Gilbert
Caption: Update encourages operators to upgrade to 5G-resistant radar altimeters
Word Count: 213
The ongoing issue of potential interference to radio altimeters (radalts) and related equipment from 5G C-band cellular broadband signals has prompted the FAA to issue revised Safety Alerts for Pilots (SaFo) 21007.
New information in the revised alert contains a summary of the compliance requirements of several airworthiness directives issued earlier this year that apply to all transport- and commuter-category airplanes, as well as all helicopters, equipped with a radalt. These ADs were issued due to a determination that radalts cannot be relied upon to perform properly when they are operating in the presence of 5G C-band signals.
In addition to the previous recommendations, the alert now encourages “all operators to equip their aircraft with 5G C-band tolerant [radalts] as soon as possible.” Such upgraded equipment was not widely available when the alert was originally published. In addition, there continues to be concerns with the “cumulative effects” of interference on associated aircraft systems that rely on radalt inputs.
The alert notes that those associated systems include TAWS, GPWS, TCAS, PFD, windshear detection systems, altitude safety callouts and aural warnings, 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.