5G and Aviation: the Aftermat

by Robert W. Poole, Jr.

Well, AT&T and Verizon turned on their new 5G towers in much of the United States this month—and aviation has not ground to a halt. The majority of the U.S. airline fleet, it turns out, have radar altimeters which the Federal Aviation Administration (FAA) has now judged can be operated at most of the airports where the telecom companies have at least temporarily taken measures to reduce possible interference with altimeters and other avionics. But most commercial landings thus far have not been under serious low-visibility conditions. Flights that would have to use radar altimeters to land safely at some airports under Instrument Flight Rule (IFR) conditions would have been canceled under current FAA protocols.

The question I asked in the November and December editions of this newsletter [Aviation Policy News] —how FAA and the U.S. Department of Transportation (US DOT) could have done so little after receiving the October 2020 Radio Technical Commission for Aeronautics (RTCA) report identifying serious signal interference risks—has not been fully answered. FAA did notify the Federal Communications Commission (FCC) about the problem in late 2020, as noted in a front-page Wall Street Journal article on Jan 21. When FCC ignored this warning, the aviation community, led by US DOT, should have carried out a large-scale public information campaign right then, prior to the FCC spectrum auctions. Had that occurred, the bidders would have taken into account the possible need to modify their tower locations and strength near airports and might have bid somewhat less than the $80 billion the government received.

Another question is why this problem has not occurred in other developed countries. A partial answer crossed my screen as I was writing this month’s issue. CNN Business posted “Europe Rolled Out 5G Without Hurting Aviation. Here’s How,” by Charles Riley and Joseph Ataman, to whom we should be grateful. As they report, the European Union Aviation Safety Agency (EASA) told CNN Business: “The technical data received from EU manufacturers offers no conclusive evidence for immediate safety concerns. . . . At this time, EASA is not aware of any in-service incidents caused by 5G interference.” And the U.K. Civil Aviation Authority had basically the same message.

However, this is not a case of he-said, she-said. There are real differences in how 5G is being implemented in Europe, compared with the United States. The underlying U.S. aviation concern is that some 5G signals could be emitted at frequencies slightly above the assigned band, where they could overlap the signals used in radar altimeters and other onboard avionics.

In Europe, the authorized 5G spectrum is between 3.4 and 3.8 GHz. But in this country, the 5G spectrum bought by ATT and Verizon is 3.7 to 3.98 GHz. Radar altimeters operate between 4.2 and 4.4 GHz, which sounds like it’s sufficiently separated from 3.98 GHz. But the RTCA report and other data suggest that spurious signals in the 3.98 range could interfere with radar altimeters unless the 5G towers are located far enough from runways to make that impossible. France’s National Frequency Agency worked with its aviation safety regulator to ensure that 5G antennas near 17 major French airports comply with limits on height, distance from runways, and power output, and are also required to be tilted away from flight paths.

No such coordination between FAA and FCC took place, either before or after the 5G spectrum auction. This is a serious institutional failure, and thus far no one has been held accountable.

Originally published by Reason Foundation. Republished with permission.