The U.S. Transportation Department said on September 30 it would furlough more than 11,000 employees at the Federal Aviation Administration (FAA), or about 25% of its staff, if government funding lapses. 

According to Reuters, U.S. airlines warned that a federal government shutdown, which began at midnight EDT, would 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. 

Around 45% of airfreight is transported in the belly of passenger planes, according to AirCargoNews. 

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. It is already running about 3,800 controllers short of targeted staffing levels. 

The National Transportation Safety Board said about 25% of its 400 employees would be furloughed but it would still be able to launch new investigations into air accidents and other incidents. 

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

On September 20, the trade association Airlines for America, urged “elected leaders to act with urgency and in good faith to identify a solution.” 

Reuters reports that, in 2019, during a 35-day U.S. government 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.