The leaders of America’s largest airlines are warning of a “catastrophic disruption” to travel and shipping operations if telecommunication companies rollout 5G technology without limiting use near airports.

Chief executives of American Airlines, JetBlue Delta Air Lines, United Airlines, and Southwest Airlines, as well as officials from FedEx Express and UPS Airlines, wrote to Transportation Secretary Pete Buttigieg and other U.S. government officials saying that it would be an “economic calamity” if Verizon and AT&T proceed with the new technology before necessary upgrades and changes have been made to aviation equipment.

Verizon and AT&T have already delayed the launch of their new C-Band 5G service twice after warning from airlines and pressure from the White House.

These two companies won the majority of contracts worth a few billion dollars to operate 5G in the 3.7 – 3.98 GHz frequency bands, which was originally supposed to roll out on Dec. 5. They agreed to buffer zones around 50 airports to reduce interference risks, but the problem is many of the major airports are reportedly not included in the list

Airline CEOs don’t think they’re equipped for the new technology and worry it will interfere with critical devices, including tools used to measure the altitude of a plane.

“We are writing with urgency to request that 5G be implemented everywhere in the country except within the approximate two miles of airport runways as defined by the FAA on January 19, 2022,” the CEOs stated, adding, “to be blunt, the nation’s commerce will grind to a halt.”

According to Reuters, some airlines are even considering canceling international flights amid the rollout.

“In addition to the chaos caused domestically,” the letter continues, the lack of certified planes “could potentially strand tens of thousands of Americans overseas.”

In a reported separate letter, United Airlines said “The federal government’s current 5G rollout plan will have a devastating impact on aviation, negatively affecting an estimated 1.25 million United passengers, at least 15,000 flights and much-needed goods and tons of cargo traveling through more than 40 of the largest airports in the country annually.

Airlines are now hanging on by a thread and hoping the federal government will intervene by blocking the technology before it’s deployed on Jan. 19.