The acting head of the US Federal Aviation Administration (FAA) says that budget cuts approved by House Republicans would cause the agency to furlough thousands of workers and stop hiring new air traffic controllers, making summer air travel worse.

The FAA Acting Administrator Billy Nolen said in a letter to lawmakers that spending cuts also would slow efforts to modernize technology, including an alert system that failed in January and briefly grounded planes around the country.

Nolen issued the warning in a required report to Congress about a shortage of air traffic controllers. He said the FAA is on pace to hit its goal of hiring 1,500 controllers by the end of September and is chipping away at a shortage that was made worse by the pandemic, when the agency suspended training new controllers.

“Despite these efforts, the spending cuts recently passed by the House of Representatives would wreak havoc on summer air travel,” Nolen told lawmakers.

Last month, the House approved legislation to raise the US debt limit and ensure that the government can pay its bills. But in a close, party-line vote, Republicans attached deep cuts in domestic spending, plus restrictions on the IRS and a ban on student-loan relief.

The House-passed measure is almost certain to be blocked in the Senate or killed with a presidential veto, but Republicans hope they can force President Joe Biden to negotiate and accept deeper domestic cuts than he would prefer.

According to the report that Nolen sent to Congress, the FAA ended last September with 10,578 certified controllers – short of its target of 12,062 – with another 3,000 people in various stages of training.