Federal transportation officials want AT&T and Verizon to delay the release of expanded 5G wireless services this week because of fears of signal interference that they said could pose risks to flight safety. The wireless companies said no on Sunday.
The Federal Aviation Administration and the transportation secretary asked the two wireless companies to delay their introduction of new 5G technology for up to two weeks.
Failing to reach a deal will force the US aviation sector to take steps to protect the safety of the traveling public. These steps will cause widespread and unacceptable disruption as airplanes divert to other cities or flights are canceled, causing ripples throughout the U.S. air transportation system.
AT&T and Verizon said on Sunday that they would proceed with their 5G expansion. The companies said that the aviation industry had nearly two years to upgrade equipment that might be affected by the new spectrum use.
John Stankey, the chief executive of AT&T, and Hans Vestberg, the chief executive of Verizon, wrote in a letter that the question of whether 5G operations can safely coexist with aviation has been settled.
The fight could add to the turmoil that has been afflicting airlines and their passengers in the past week, as carriers battled bad winter weather and a coronaviruses wave that thinned their staffing during a peak holiday travel period.
The wireless carriers agreed to a delay of 30 days. Federal officials wanted to give them more time to identify critical airports that need a buffer zone.
For six months, until early July, the companies said they would comply with a version of restrictions now in place in France, which would sharply limit the signals at issue around busy airport runways.
The 5G expansion is a priority for the wireless carriers. The C-band spectrum, which was auctioned off last year, will allow for faster signals and greater geographic reach for both companies. The carriers have not yet said which areas will get the new services this week, or how many customers they will cover, but they did say last month that the new spectrum will reach 100 million customers by March. AT&T plans to reach 70 million people in the United States by the end of the year.
There is a fight between government regulators. The FCC has urged wireless carriers to expand their 5G networks, while the FAA has sought to slow things down.
Brendan Carr, a Republican F.C.C. commissioner appointed by President Donald J. Trump, sent a letter to Mr. Buttigieg about the agency's objections.
Mr. Carr wrote that the request for the delay was not supported by the science, engineering or law.
A spokeswoman for the F.A.A said that the agency was looking at the letter.
She said that U.S. aviation safety standards would guide their next actions.
