Officials say the system is likely to be operating normally in time to handle the Thanksgiving travel rush.

The Federal Aviation Administration said airplane departures could resume late Friday evening Eastern time. Passengers should contact their airlines for information about their flights, the FAA said.

The ripple effect from the stoppage could be felt for days, however.

More than 2,500 flights were cancelled in the US on Saturday, and hundreds more were delayed, according to FlightAware, a website that tracks flight disruptions.

Transportation Secretary Sean Duffy warned Americans traveling that getting air traffic back to normal won't be quick.

International flights are being handled on a case-by-case basis, according to Homeland Security Secretary Markwayne Mullin.

San Francisco airport said that flights headed across the Pacific Ocean were cleared to leave the airport from Friday evening. That included flights destined for Hawaii and Asia.

Europe's aviation agency suspended U.S.-bound departures at the request of the FAA from 5 pm Eastern on Friday until midnight.

Airlines are obligated to offer free rebooking on another flight for travelers who want to continue their journey, or a refund if their flight was canceled and they decide not to take the trip.

New technology being hooked up to the nation's air traffic control system overloaded antiquated equipment, Trump administration officials said.