AT&T and Verizon said they will delay the launch of their 5G networks in C-band spectrum for two weeks, until January 19.

The move represents a reversal from the companies' previous position. On late Sunday, the companies rejected the notion of a two-week delay as "an unprecedented and unwarranted circumvention of the due process."

By late Monday, the companies appeared to have reconsidered.

"We know aviation safety and 5G can co-exist and we are confident further collaboration and technical assessment will allay any issues," AT&T said. Verizon, meanwhile, said the delay "promises the certainty of bringing this nation our game-changing 5G network in January."

At issue are concerns in the airline industry that 5G operations in C-band spectrum could interfere with some radio altimeters in aircraft. The gadgets are used to aid pilots landing in low-visibility conditions. Although the FCC auctioned C-band spectrum for 5G early last year, the airline industry has ratcheted up warnings in recent months that 5G in C-band spectrum could potentially interfere with thousands of flights per day around the country.

As a result, US Transportation Secretary Pete Buttigieg and Federal Aviation Administration chief Steve Dickson on New Year's Eve asked AT&T and Verizon to delay their launch of 5G in C-band spectrum by two weeks.

The two carriers initially rejected that request, but now they have acquiesced.

This is the second 5G launch delay the carriers have agreed to. Both Verizon and AT&T initially had planned to launch 5G in their C-band holdings in December, but pushed that back to January 5 due to the interference concerns.

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano