US Transport Secretary Sean Duffy warned on Tuesday that if the federal government shutdown continues for another week it could lead to “mass chaos” and force him to close some airspace, which could upend American aviation.
There have already been delays at US airports because the Federal Aviation Administration slows down or stops traffic temporarily when it is short of controllers, many of whom are calling in sick as they work without pay during the shutdown.
Last weekend saw some of the worst staff shortages. On Sunday, flights at Newark Liberty International Airport in New Jersey were delayed for several hours.
More than 60,000 air-traffic controllers and Transport Security Administration officers are working without pay, and the White House has warned that increasing absenteeism could mean chaos at check-in lines.
“If you bring us to a week from today, Democrats, you will see mass chaos, you will see mass flight delays. You'll see mass cancellations, and you may see us close certain parts of the airspace, because we just cannot manage it,” Mr Duffy told reporters. “We will restrict the airspace when we feel it's unsafe.”
US airline shares slumped on the news, with Delta, United Airlines and American Airlines all falling more than 5 per cent.
Tuesday was the 35th day of the shutdown. If it drags into Wednesday it will become the longest shutdown in US history.
The Republican-led House of Representatives passed a massive spending bill at the end of September and then adjourned, leaving the Senate with the decision to take it or leave it.
The bill does not have enough backing from Democrats to pass in its current form. They say it will force up health insurance costs for millions.
On Tuesday, there were more than 2,300 flight delays as the FAA imposed delays in Phoenix and expects to delay flights in Houston after seeing staffing issues in Denver, Detroit and elsewhere.
FAA Administrator Bryan Bedford told Fox Business on Tuesday that at the agency's largest 30 airports “anywhere from 20 to 40 per cent of our controllers aren't coming to work".
