CEOs of the nation’s largest airlines warned in a letter that there could be “catastrophic disruption” to flights when 5G is set to deploy on Wednesday.

The airlines wrote in a letter obtained by Reuters:

We are writing with urgency to request that 5G be implemented everywhere in the country except within the approximate 2 miles of airport runways at affected airports as defined by the FAA on January 19, 2022. This will allow 5G to be deployed while avoiding harmful impacts on the aviation industry, traveling public, supply chain, vaccine distribution, our workforce and broader economy.

The chief executives of Alaska Airlines, American Airlines, Atlas Air, Delta Air Lines, Hawaiian Airlines, JetBlue Airways, Southwest Airlines, United Airlines, FedEx, and UPS all signed the letter:

We further ask that the FAA immediately identify those base stations closest to key airport runways that need to be addressed to ensure safety and avoid disruption in a manner that is narrowly focused and consistent with the agreement established on January 3, 2022

On January 3, AT&T and Verizon agreed to delay the 5G rollout from January 5 until January 19. They also agreed to buffer zones surrounding 50 airports to minimize potential interference, according to Reuters. The two telecom giants won close to all of the 5G C-Band spectrum last year in an $80 billion auction.

The airline executives warned of potential “catastrophic disruption.” They said there are “huge swaths of the operating fleet that may need to be indefinitely grounded,” in a letter addressed to White House National Economic Council director Brian Deese, Transportation Secretary Pete Buttigieg, Federal Aviation Administration (FAA) Administrator Steve Dickson, and Federal Communications Commission (FCC) Chairwoman Jessica Rosenworcel.

The 5G rollout could also cause delays in the supply chain, the airlines warned. “Immediate intervention is needed to avoid significant operational disruption to air passengers, shippers, supply chain and delivery of needed medical supplies,” the letter said.

In addition, the rollout could leave up to 100,000 passengers stranded at airports across the country. “Unless our major hubs are cleared to fly, the vast majority of the traveling and shipping public will essentially be grounded,” the executives said. “This means that on a day like yesterday, more than 1,100 flights and 100,000 passengers would be subjected to cancellations, diversions or delays.”