PBS News Hour

JUDY WOODRUFF

Verizon and AT&T are forging ahead with their plan to switch to new high-speed 5G wireless service nationwide, but with an important exception, near U.S. airports and runways. Those exceptions were made yesterday because of fears of that the new technology could interfere with plane technology and potentially impact landings. Our science correspondent, Miles O'Brien, is here to unpack it all for us. Hello, Miles, to you. So, tell us, exactly, what is the problem here?

MILES O'BRIEN

Hello, Judy. The device in question here is called a radar altimeter, a radio altimeter. It's a device on an airliner which gives pilots very precise information of their relative distance to the ground the closer they get to it. It's crucial during the landing phase in bad weather. And, without it, we couldn't have the proverbial safe landing on that dark and stormy night. So, any time the aviation industry gets word of something getting close to that piece of the spectrum where this device operates, they get nervous. And that's what led to this fight.

JUDY WOODRUFF

And, Miles, we know this was supposed to have been resolved of some time ago. The two federal agencies involved, the FCC, federal communications commission, and the FAA, of course, the Federal Aviation Authority, are at different places here. What has happened? Why hasn't it been resolved?

MILES O'BRIEN

Well, the aviation community has been saying this is a big problem. And the communication industry has said that the aviation industry is focused on worst-case scenarios that are improbable. Well, that's what the aviation industry does. So, there is kind of a clash of cultures here. The concerns are potentially real. These frequencies tend to spill outside of their lanes. And it's very important that there are specific filters on the devices, so they don't pick up stray signals, giving bad indications to the pilots.

JUDY WOODRUFF

So -- but, I mean, you think about all this. Surely, the FAA considered all this as they were moving forward.

MILES O'BRIEN

Well, the FAA was considering it, but the FCC was pushing as well. And it was a little bit like a game of chicken to see, who is going to fix the problem? Would the transmitters on the ground be modified in some fashion? Would the power be reduced, the antennas re-aimed? Would there be bubbles around airports? Or would the airlines have to fix all of their radar altimeters, so the obsolete ones are no longer in the fleet? Which are the ones that might cause trouble?

JUDY WOODRUFF

So, Miles, given all this, what do we expect to happen here? I mean, can they resolve this so that the airlines, the FAA feels comfortable and 5G goes forward?

MILES O'BRIEN

It can be done. Forty countries have done this. And what this compromise that was announced is a lot like what has occurred in Europe and elsewhere, providing lower transmission power, directing those antennas, creating corridors for runways. All that is in the compromise. So that will stay in place for a while, until such time as the aviation fleet gets upgraded with radar altimeters that aren't likely to be fooled by 5G. So, this problem will work itself out over time. The compromise will probably be here for a while, as it takes a while for this equipment to be retired.

JUDY WOODRUFF

Well, it sounds complicated, but I know, first and foremost, people who fly on passenger airliners or anybody who gets in a plane wants to be sure they're safe.

MILES O'BRIEN

Absolutely. And that is uppermost here. And, obviously, the aviation industry doesn't want to be in a position where something like this causes an accident, particularly in the wake of the problems 737 MAX scenario, where the FAA was accused of not being aggressive enough identifying a safety issue. In this case, they're out in front of it. The compromise is in place, and people can feel safe flying for the foreseeable future.

JUDY WOODRUFF

Miles O'Brien reporting on all things aviation for us. Thank you, Miles.

MILES O'BRIEN

You're welcome, Judy.