Wireless carriers Verizon and AT&T say they will go ahead with plans to switch on high speed 5G service nationwide Wednesday, except near airports and runways, due to worries that high tech radio signals could interfere with navigational systems on some aircraft.

Emirates and other long-haul international airlines have canceled or rerouted flights into the U.S. in response. Carriers that use the Boeing 777, a long-haul aircraft, were particularly concerned, with two Japanese airlines citing the aircraft's vulnerability to 5G signals as reasons behind their schedule changes.

Because of those safety concerns, the Federal Aviation Administration has issued notices to airlines that would prohibit certain planes from landing at dozens of airports around the country during poor weather conditions.

The move by the telecom giants to limit 5G near airports averts what domestic airlines say could have been "catastrophic" flight delays and cancellations for thousands of travelers if Verizon and AT&T had fully implemented 5G service after midnight on Tuesday, as planned.

Nonetheless, Emirates announced that it is stopping flights to Boston, Chicago, Dallas-Fort Worth, Houston, Miami, Newark, New Jersey, Orlando, Fla., San Francisco and Seattle. Flights to Los Angeles, New York and Washington will continue as scheduled.

The big wireless companies agreed to delay their rollout of 5G, or fifth generation wireless service, twice before — in December and again in early January — to try to work out a compromise with the airline industry, the FAA and other stakeholders.

The push for 5G

The wireless industry calls 5G a game changer. It provides stronger connectivity and faster download speeds on cellphones and other wireless devices, making streaming, gaming and other uses better than ever.

Ted Rappaport, an electrical engineering professor at NYU and director of the research center NYU Wireless, says cellphone technology has gone through big upgrades about every 10 years, starting with those big old brick phones in the 1980s and with the latest upgrade marking a huge jump.

"The internet came in spades and 4G with the smartphone around 2010," says Rappaport, who adds that 5G will be exponentially better.

"5G is so much faster in terms of data rate, in terms of capability, in terms of radio spectrum," he says. "It basically brings a fiber optic cable wirelessly to the pocket of every human. So, 5G truly is revolutionary."

Airlines worry it could disrupt a key piece of equipment

Rappaport says the wireless carriers need more and more radio spectrum to carry more and more bits to our smartphones. The Federal Communications Commission auctioned off radio spectrum to the wireless carriers a big chunk of the "C" band of radio spectrum for about $80 billion in 2020. The segment of the spectrum in the "C" band purchased by AT&T and Verizon happens to sit right next to the frequencies used by radio altimeters in aircraft.

"The radio altimeters on our aircraft determine not only the height above the ground ... as we come in for a landing or we're taking off, but they're tied to many other systems in our aircraft," said Joe DePete, head of the Air Line Pilots Association, in a recent interview with Yahoo Finance.

Altimeters are critical for pilots to use during bad weather when visibility is poor. Pilots like DePete worry that strong 5G signals from cellphone towers placed close to airport runways could interfere with the radio altimeters.

"The issue is that some of the older planes and older aircraft equipment that were built maybe 30 or 40 years ago do not have very good band pass filters. They don't have very good filters on their receivers," says Rappaport.

It's similar to the way that CB radios would sometimes interfere with old TV sets, before cable and digital signals, according to Rappaport.

"The underlying issue here is that radio signals cannot be perfectly confined to their assigned frequency band and will result in some energy being transmitted in neighboring bands," adds Northwestern University electrical engineering professor Randall Berry. "Also, radio receivers cannot perfectly filter out the signals transmitted in neighboring bands and so will receive some out-of-band interference. Both of these effects result in interference from a neighboring band."

Due to the possibility of interference with such critical navigational equipment, the FAA has issued so-called Notices Of Air Missions that would prohibit certain aircraft from landing at dozens of airports around the country, even at times when skies are clear and visibility is not poor.

The CEOs of 10 passenger and cargo airlines, including American, Delta, Southwest, United and FedEx, are urging federal officials, including Transportation Secretary Pete Buttigieg, to establish 2-mile 5G-free buffer zones around runways.

"To be blunt, the nation's commerce will grind to a halt" unless 5G service is restricted around major airports, the CEOs said in a letter Monday to government officials.

"Unless our major hubs are cleared to fly, the vast majority of the traveling and shipping public will essentially be grounded," the CEOs said, adding that on a day like this past Sunday "more than 1,100 flights and 100,000 passengers would be subjected to cancellations, diversions or delays," the CEOs' letter adds.

The wireless carriers say 5G doesn't pose a risk

AT&T and Verizon say transmissions from their 5G towers will not interfere with aircraft radio altimeters and other aviation electronics, and they say that the technology is being used safely in more than 40 other countries.

But the wireless providers nonetheless agreed on Tuesday to postpone turning on 5G towers around some airports, although AT&T and Verizon did not immediately say how many, nor for how long, this delay of 5G implementation would continue.

In a statement, AT&T said "we have voluntarily agreed to temporarily defer turning on a limited number of towers around certain airport runways as we continue to work with the aviation industry and the FAA to provide further information about our 5G deployment, since they have not utilized the two years they've had to responsibly plan for this deployment. We are frustrated by the FAA's inability to do what nearly 40 countries have done, which is to safely deploy 5G technology without disrupting aviation services, and we urge it do so in a timely manner."

But former FAA Administrator Michael Huerta, who served in the role from 2010-2018, points out that the 5G towers near airports in other countries are either turned off or operating at low power near airports, with transmitters pointing down toward the ground and away from aircraft, and he urges all involved to take more time to fully examine the safety of 5G signals.

"What really needs to happen is the very detailed technical analysis — airport by airport, aircraft type by aircraft type — to determine how real the interference potential actually is."

In a statement, President Biden thanked AT&T and Verizon for reaching an agreement that "will avoid potentially devastating disruptions to passenger travel, cargo operations, and our economic recovery."

"This agreement protects flight safety and allows aviation operations to continue without significant disruption and will bring more high-speed internet options to millions of Americans," Biden added.