American Airlines flights have resumed after being cleared to fly by federal regulators an hour after all flights were grounded causing widespread disruption to the Christmas getaway in the US.
Just before 7 am eastern time (12pm UK time) the Federal Aviation Administration ordered all American Airlines flights grounded in the States at the airline's request.
American had reported a technical issue affecting its entire system with millions traveling for the holiday.
The ground stop, according to the time stamps on the FAA's orders, lasted exactly one hour.
In a statement, the airline said a "vendor technology issue" had caused the issue and it was "all hands on deck" to minimise further disruption.
"We sincerely apologise to our customers for the inconvenience this morning," the airline said.
"It's all hands on deck as our team is working diligently to get customers where they need to go as quickly as possible."
Flights are still showing delays as the airline recovers from the nationwide issue, but real-time tracking website Flightradar24 shows planes taking off again at a number of major US travel hubs.
The groundings couldn't come at a worse time for the millions of travelers expected to fly over the next 10 days.
Many flights during the holidays are sold out, which makes cancellations even more disruptive than during slower periods. Even with just a brief outage, the cancellations have a cascading effect that can take days to clear up.
The Transportation Security Administration expects to screen 40 million passengers over the holidays and through January 2.
