An estimated 45% of the U.S. commercial fleet has been cleared for low-visibility landings at some airports where 5G C-Band will be deployed, says the FAA
Days after the Federal Aviation Administration (FAA) issued more than 1,400 warnings to pilots about the possibility that on-board aviation systems may be disrupted by 5G C-Band operations, the federal agency has cleared for use two radar altimeters used in some Boeing and Airbus jets. According to the agency, this easing of restrictions will enable 45% of U.S. aircrafts to make low-visibility landings.
The Notices to Airmen (NOTAMs), issued last week, warned pilots that altimeters, automated landing and heads-up displays/enhanced flight vision systems for aircraft should be considered unreliable in specific geographic areas, as should the use of helicopter autopilot hover modes.
Radio altimeters supporting these systems operate between 4.2-4.4 GHz; C-Band 5G operations will initially begin at around 3.7 GHz. While there is substantial RF distance between those two types of operations, the FAA is still concerned about even the possibility of out-of-band interference with altimeter systems, which were not designed to deal with a changing RF environment or terrestrial 5G operations.
But now, several aircraft models, including Boeing’s 737, 747, 757, 767, MD-10 and MD-11 and the Airbus A310, A319, A320, A321, A330 and A350, have been cleared for low-visibility landings, even in locations where 5G is deployed. These aircraft and altimeter approvals, said the FAA, open “runways at as many as 48 of the 88 airports most directly affected by 5G C-Band interference.”
“Even with these new approvals, flights at some airports may still be affected,” cautioned the agency. “The FAA also continues to work with manufacturers to understand how radar altimeter data is used in other flight control systems.”
In December, AT&T and Verizon agreed to pause their C-Band plans until early January following warnings issued by the FAA that the 5G spectrum could interfere with aviation safety systems. More recently, when the FAA Chief Steve Dickson and U.S. Transportation Secretary Pete Buttigieg asked Verizon and AT&T to delay their C-Band roll out for an additional two weeks, the carriers first rejected the new request. The pair changed their tune the following day, however, ultimately agreeing to the two-week delay that will now put C-Band activation at January 19 instead of January 5.
