DUBAI, United Arab Emirates — Some flights to and from the U.S. were canceled on Wednesday even after AT&T and Verizon scaled back the rollout of high-speed wireless service that could interfere with aircraft technology that measures altitude.
International carriers that rely heavily on the wide-body Boeing 777, and other Boeing aircraft, canceled early flights or switched to different planes following warnings from the Federal Aviation Administration and the Chicago-based plane maker.
Airlines that fly only or mostly Airbus jets, including Air France and Ireland's Aer Lingus, seemed less affected by the new 5G service.
Airlines had canceled more than 320 flights by Wednesday evening, or a little over 2% of the U.S. total, according to FlightAware. That was far less disruptive than during the Christmas and New Year’s travel season, when a peak of 3,200, or 13%, of flights were canceled on Jan. 3 due to winter storms and workers out sick with COVID-19.
A trade group for the industry, Airlines for America, said cancellations weren't as bad as feared because AT&T and Verizon agreed to temporarily reduce the rollout of 5G near dozens of airports while industry and the government work out a longer-term solution.
At O'Hare International Airport in Chicago, Sudeep Bhabad said his father-in-law's flight to India was cancelled.
“They have to resolve this problem," Bhabad said. “It would have been a lot better if they had resolved it way before and we knew this in advance, instead of, like, finding out when we are here at the airport.”
Similar mobile networks have been deployed in more than three dozen countries, but there are key differences in how the U.S. networks are designed that raised concern of potential problems for airlines.
The Verizon and AT&T networks use a segment of the radio spectrum that is close to the one used by radio altimeters, devices that measure the height of aircraft above the ground to help pilots land in low visibility. The Federal Communications Commission, which set a buffer between the frequencies used by 5G and altimeters, said the wireless service posed no risk to aviation.
But FAA officials saw a potential problem, and the telecom companies agreed to delay their rollout near more than 80 airports while the agency assesses which aircraft are safe to fly near 5G and which will need new altimeters.
The FAA gave approval Wednesday for more types of planes to land in low visibility near 5G signals, including the Boeing 777. By evening, however, nearly 40% of the U.S. airline fleet was still waiting to be cleared. That percentage was expected to shrink as the FAA continued to review other planes and altimeters.
“I assume whatever process they are using could be used to clear the rest,” said Randall Berry, a professor of electrical engineering at Northwestern University.
The FAA says there are several reasons why the 5G rollout has been more of a challenge for airlines in the U.S. than in other countries: Cellular towers use a more powerful signal strength than those elsewhere; the 5G network operates on a frequency closer to the one many altimeters use, and cell tower antennae point up at a higher angle. A telecom industry group, CTIA, disputes the FAA's claims.
Some experts say poor coordination and cooperation among federal agencies is as much to blame as any technical issues.
“The fights around this from federal agencies have just gotten more and more intense," said Harold Feld, an expert on telecom policy at the advocacy group Public Knowledge.
The European Union Aviation Safety Agency said it wasn't aware of any problems on the continent caused by 5G interference. To mitigate airline interference, French telecom providers reduce the strength of their high-speed networks near airports.
Boeing Co. said in a statement it would work with airlines, the FAA and others to ensure that all planes can fly safely as 5G is rolled out.
In the meantime, airlines scrambled to adjust to the new reality.
Emirates, which relies heavily on the 777, halted flights to several American cities on Wednesday, but maintained service to Los Angeles, New York and Washington.
“We hope to resume our U.S. services as soon as possible,” the state-owned airline said.
Tim Clark, president of Emirates, told CNN it was “one of the most delinquent, utterly irresponsible” situations he’d ever seen as it involved a failure by government, science and industry.
Japan’s All Nippon Airways canceled 20 flights to cities such as Chicago, Los Angeles and New York, while Japan Airlines said eight of its flights were affected Wednesday.
Air India said on Twitter it would cancel flights to Chicago, Newark, New York and San Francisco because of the 5G issue. But it also said it would try to use other aircraft on U.S. routes — a course several other airlines took.
Korean Air, Hong Kong’s Cathay Pacific and Austrian Airlines said they substituted different planes for flights that were scheduled to use 777s. Germany’s Lufthansa swapped out one kind of 747 for another on some U.S.-bound flights.
American Airlines Chief Operating Officer David Seymour said in a memo to staff that the carrier canceled four flights while it awaited FAA approval of equipment on its Airbus aircraft.
Choi Jong-yun, a spokeswoman of Asiana Airlines, which uses Airbus planes for flights to the U.S., said it hadn't been affected so far.
FCC Chairwoman Jessica Rosenworcel said in a statement that the 5G “deployment can safely co-exist with aviation technologies in the United States, just as it does in other countries around the world.” However, she urged the FAA to conduct its safety checks with "both care and speed.”
Gambrell reported from Dubai. Associated Press video journalist Teresa Crawford in Chicago and AP writers Kim Tong-hyung in Seoul, South Korea, Yuri Kageyama in Tokyo, Ken Moritsugu in Beijing, David McHugh in Frankfurt, Germany, Frank Jordans in Berlin, Angela Charlton in Paris, Kelvin Chan in London and Isabel DeBre in Dubai contributed to this report.