WASHINGTON (Reuters) — The Department of Transportation said on Tuesday that more than 11,000 employees at the Federal Aviation Administration will be furloughed if government funding lapses at midnight Eastern time.

U.S. airlines have warned that a partial federal government shutdown could strain American aviation and slow flights, as air traffic controllers and security officers would be forced to work without pay and other functions would be halted.

The Transportation Department said the FAA would continue to hire air traffic controllers, and field training of controllers would continue. During prior government shutdowns, the FAA suspended hiring and most training of air traffic controllers.

More than 13,000 current controllers would be required to continue working but would go unpaid until the shutdown ended, the FAA said.

The FAA has about 45,000 employees. In total, the Transportation Department would furlough 12,200 of 53,717 employees, including those at the FAA.

The FAA also said certification activities would continue for operational safety functions of aircraft and engines, as well as commercial space launch oversight and licensing.