Steep spending cuts contained in a House Republican budget bill would dramatically exacerbate a shortage of U.S. air-traffic controllers that has already led to a reduction in flights to New York this summer, officials said May 5.

The Federal Aviation Administration would be forced to halt hiring and training of new controllers, furlough thousands of other employees and stop work on an air-traffic computer system, agency Acting Administrator Billy Nolen said in a letter to lawmakers. The situation “would wreak havoc on summer air travel,” he said.

Transportation Secretary Pete Buttigieg called the prospect of FAA budget cuts “perfectly backward” during a period in which the agency is ramping up hiring and attempting to upgrade critical infrastructure.

“I cannot understand why house Republicans would want to vote for more cancellations and delays and that inevitably is what this would come to,” he said in an interview.

Raising the issue of controller staffing is the latest salvo in the high-stakes debate over federal spending and increasing the U.S. debt limit, which must be lifted by June 1 to avoid a potential default. House Republicans passed legislation on April 26 that would cut domestic spending by 22%.

House Speaker Kevin McCarthy and other Republican leaders didn’t immediately respond to requests for comment.

The number of air-traffic controllers has dwindled over the past decade as a result of multiple setbacks to hiring and training, including the COVID-19 pandemic and various government shutdowns, according to the FAA.

There were 10,578 fully certified controllers as of September 2022. Another 2,800 people were in various stages of being trained, but it can take years to become certified.

A shortage of controllers has already had impacts on the U.S. aviation system.

The FAA facility that guides aircraft to and from New York’s major airports has only 54% of the optimal number of fully trained controllers, which prompted the agency in March 2023 to urge airlines to cut flight schedules by as much as 10% during the busy summer season.

In 2022, a shortage of controllers in a Florida facility was one reason for a surge in flight delays in the region.

Overall, weather and issues with airline equipment and staffing cause the most delays and cancellations, according to government data. But even small additional disruptions in congested regions such as New York can have a significant impact.

Potential budget cuts also come in the wake of a rare shutdown of all departures last January prompted by the failure of an FAA computer system that provides safety notices to pilots. The agency is attempting to modernize it.