UPDATE Earlier this month, Inside Towers reported that several airlines and aviation manufacturers sought to make the temporary restrictions AT&T and Verizon agreed to for 5G operations on C-band (3.7 GHz) near airports permanent. Now, the FAA seeks that outcome, too, plus restrictions for smaller telecoms as well.
Acting FAA Administrator Billy Nolen said in a letter to the FCC and NTIA he wants the restrictions mandated for 19 smaller telecoms and other spectrum holders. “Aviation safety would be compromised if the U.S. government does not codify certain additional operating limits in the 5G C-band environment,” wrote Nolen, according to Reuters. He raised the specter of flight disruptions if the FCC doesn’t mandate the mitigations. It’s unclear if the Commission has the authority to retroactively impose conditions on companies that purchased spectrum at auction.
The issue is fear about 5G operations on C-band possibly interfering with aviation radio altimeters. The devices give data on a plane’s height above the ground and are critical for bad-weather landings.
Though the FAA didn’t raise any concerns when the FCC began the proceeding under former Chairman Pai, it did at the last minute before the agency’s vote to open up part of the C-band for 5G, Inside Towers reported. AT&T and Verizon paid a combined $82 billion at auction for their C-band licenses. In June, they agreed to delay some C-band 5G operations around certain airports until July 2023. In a deal with the FCC and the FAA, the telecoms agreed to a phased-in rollout to give the airlines time to upgrade or replace radio altimeters that could be vulnerable to interference.
The airline industry is “aggressively retrofitting” planes that fly in the U.S. with RF filters on the altimeters, according to Nolen. But he added “data indicates that even retrofitted aircraft would be susceptible to interference if the [FCC] report and order is not modified, resulting in renewed concerns about unsafe interference.”
The FAA has cut the size of zones around airports where Verizon and AT&T cannot fully use their 5G tower sites, notes Reuters. Nolen said the voluntary mitigations by AT&T and Verizon “have resulted in the safe deployment of 50,000 wireless antennas” across the country.
By Leslie Stimson, Inside Towers Washington Bureau Chief