Despite pleas from NATA and many others in the aviation community, the US FCC proceeded with an auction on 8 December of flexible-use overlay licences for a portion of the 3.7-4.2 GHz spectrum band suitable for 5G operations to the telecommunications industry. NATA, along with 14 other leading aviation groups, supported a letter requesting a suspension of the auction to provide time to fully understand the safety implications of this transaction. Extensive study and research by the industry suggests that without mitigation, the deployment of 5G networks in this frequency band may pose safety risks due to radio interference with radar altimeters.

“The safety of our industry is foremost in our mission and drives everything we do,” says NATA vice president of regulatory affairs John McGraw. “We were pleased to collaborate with and support the efforts of a strong coalition of leading aviation organisations to inform the FCC about the risk to aviation from this significant safety issue. We will continue to monitor the situation and support further research and efforts that help ensure the safety of our airspace system,”

The group of 15 aviation associations sent a letter to the FCC expressing concern over frequency spectrum relocation affecting radar altimeters, a critical flight safety tool.

“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 to 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 on board a civil aircraft that 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 to 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.

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.