An employee with the Transportation Security Administration (TSA) checks the documents of a traveler at Reagan National Airport in Washington, U.S., January 6, 2019. REUTERS/Joshua Roberts

By David Shepardson

WASHINGTON (Reuters) -The U.S. Transportation Department said on Tuesday more than 11,000 employees at the Federal Aviation Administration, about a quarter of its staff, will be furloughed if government funding lapses at midnight.

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.

With an eye on keeping the skies safe, more than 13,000 current air traffic controllers would be required to continue working, but would not be paid until the shutdown ended, the FAA said.

The FAA is about 3,800 controllers short of targeted staffing levels, but even if government funding is halted, the FAA would continue to hiring and training air traffic controllers. During prior government shutdowns, the FAA suspended hiring and most training of air traffic controllers.

About 50,000 Transportation Security Administration employees who staff airport security checkpoints would also be required to keep working, but would not be paid.

In 2019, during a 35-day shutdown, the number of absences by controllers and TSA officers rose as workers missed paychecks, extending checkpoint wait times at some airports. Authorities were forced to slow air traffic in New York, which put pressure on lawmakers to quickly end the standoff.

Airline trade group Airlines for America, which represents United Airlines, Delta Air Lines, American Airlines, Southwest Airlines and others, warned that if funding lapses, "the system may need to slow down, reducing efficiency" and impacting travelers.

U.S. Travel Association, which represents airlines, hotels, car rental firms and other travel companies said partial U.S. government shutdown would cost the U.S. travel sector $1 billion per week.

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

The FAA also said certification activities would continue for operational safety functions of commercial airplanes and

engines, as well as commercial space launch oversight and licensing.

(Reporting by David Shepardson; Editing by Leslie Adler and Chris Sanders)