A group of 15 aviation associations recently 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 asked the FCC to suspend Auction 107, which began Dec. 8, 2020, despite the protests. The auction offers new flexible-use overlay licenses for spectrum in the 3.7–3.98 GHz band. GA alphabet groups want the FCC to resolve likely interference issues with radar altimeters before 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 GA associations 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 an 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 airliners, business airplanes, helicopters, and general aviation aircraft.
Without appropriate mitigations, this interference could lead to catastrophic failures, according to the study.
The study was submitted to the FCC for consideration back in October and additional information was provided to the FCC Dec 7.
The aviation associations signing onto the letter include the 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.