A MARTINEZ, HOST:
Verizon and AT&T are rolling out long-awaited 5G service across the country today, except near many airports. The two telecom giants agreed yesterday to limit the service amid concerns that 5G could interfere with safety equipment on some aircraft.
NPR's David Schaper reports.
DAVID SCHAPER, BYLINE: According to former federal aviation administrator Michael Huerta, 5G presents a problem for a critical navigational tool called a radio altimeter.
MICHAEL HUERTA: It's a piece of equipment onboard modern aircraft that enable aircraft to know their position relative to the ground. And this is important when you're dealing with an inclement-weather situation, where you may not have the visibility that you would have on a blue-sky day, in order to ensure that aircraft can land safely.
SCHAPER: About a year ago, the FCC auctioned off a segment of radio spectrum for 5G to Verizon and AT&T for tens of billions of dollars. That spectrum is next to the frequencies used by radio altimeters on planes and helicopters. And the FAA worries that 5G signals will interfere with older altimeters.
NYU electrical engineering professor Ted Rappaport, who heads the research center NYU Wireless, explains it this way.
TED RAPPAPORT: It's kind of like when the television sets would get interfered with 30 or 40 years ago by a CB radio. Same kind of thing exists with radio altimeters in some of the older aircraft today.
SCHAPER: The FAA says the potential for such interference would make some aircraft altimeters useless. And the safety regulator warned it would restrict certain older aircraft from landing at certain airports. As a result, airlines say they'd be forced to cancel, reroute or delay hundreds of passenger and cargo flights a day. They warned of catastrophic flight disruptions and that the nation's commerce will grind to a halt. But AT&T and Verizon have already agreed to delay deployment of 5G twice so the FAA could further study it. But wireless companies insist 5G towers will not interfere with aircraft altimeters, and some experts agree.
Cenk Gursoy is a professor of electrical engineering and computer science at Syracuse University.
CENK GURSOY: In my opinion, there should not be that much of an interference because the separation between the two bands is substantial. It's not really - they not very close to each other.
SCHAPER: The wireless companies say 5G is deployed in about 40 other countries without aircraft interference problems. But in most of those places, the spectrum used for 5G is further away from aircraft radio frequencies. And 5G is operated at low power near airports, with transmitters pointed away from airplanes.
Gursoy says those solutions might work here.
GURSOY: They should be able to resolve this. I'm kind of puzzled that this has not been taken care of before.
SCHAPER: But there's a reason it hasn't, according to former FAA administrator Huerta.
HUERTA: This problem emerged largely because of, I think, a lack of effective communication between the FCC and the FAA before the spectrum auction was actually run at the end of 2020.
SCHAPER: The FCC approved the sale of the radio spectrum to Verizon and AT&T over the FAA's objections.
HUERTA: But we are where we are. And I think what really has to happen is very detailed technical analysis between the two industries and their regulators to ensure that 5G can be safely deployed across the U.S.
SCHAPER: Still, 5G service could lead the FAA to restrict flights at some airports, especially when there's bad weather. And a few international airlines have canceled some flights into the U.S. as a result.
David Schaper, NPR News.
(SOUNDBITE OF MELODIESINFONIE'S "MEDITATION ON GOD") Transcript provided by NPR, Copyright NPR.
