Aviation Groups Call for Halt of FCC Spectrum Auction Affecting Radar Altimeters

A group of 15 aviation associations have sent a letter to the Federal Communications Commission (FCC) expressing concern over frequency spectrum relocation affecting radar altimeters, a critical flight safety tool. The group requested that the FCC suspend Auction 107, scheduled to begin December 8, which offers new flexible‐use overlay licenses for spectrum in the 3.7–3.98 GHz band, in order to resolve likely interference issues with radar altimeters prior to the auction.

“Since 2017, the aviation industry has consistently noted during the Federal Communications Commission rulemaking process that deployment of 5G networks in this frequency band may introduce harmful radio frequency interference to radar altimeters currently operating in the globally-allocated 4.2–4.4 GHz aeronautical band,” the group wrote. “Radar altimeters are deployed on tens of thousands of civil aircraft in the United States and worldwide to support several critical safety-of-life aircraft functions throughout multiple phases of flight. Radar altimeters are the only sensor onboard a civil aircraft which provides a direct measurement of the clearance height of the aircraft over the terrain or other obstacles.”

The group’s request to suspend the auction is rooted in findings from a RTCA study on the impact of C-band mobile telecommunications interference on low range radar altimeter operations. The study revealed that 5G telecommunications systems in the 3.7–3.98 GHz band will cause harmful interference to radar altimeters on all types of civil aircraft—including large commercial transport airplanes; business, regional, and general aviation airplanes; and both transport and general aviation helicopters.  Without appropriate mitigations, such interference could lead to catastrophic failures. The study was submitted to the FCC for consideration back in October and additional information was provided to the FCC today.

The aviation associations signing onto the letter to the FCC Commissioners include Aerospace Industries Association; Airborne Public Safety Association; Air Line Pilots Association, International; Aircraft Electronics Association; Aircraft Owners and Pilots Association; Airlines for America; Cargo Airline Association; Experimental Aircraft Association; General Aviation Manufacturers Association; Helicopter Association International; National Air Carrier Association; National Air Transportation Association; National Business Aviation Association; RTCA; and Regional Airline Association.

A copy of the letter can be found here.