SAN FRANCISCO -- Federal officials halted Southwest Airlines flights from taking off on Tuesday.
By late morning on the East Coast, more than 1,500 Southwest flights had been delayed, accounting for well over half of all delays nationwide, according to FlightAware.
Southwest said on Twitter that it asked the Federal Aviation Administration to hold up departures because of "intermittent" technical issues and hoped to resume flights as soon as possible.
Then at 8:10 a.m., the FAA tweeted: "This morning@SouthwestAir experienced a technical issue with one of their internal systems. At the airline's request, the FAA paused Southwest's departures as they resolved the issue. The pause has been lifted and their service has resumed. The airline did not immediately respond to questions about the nature of the technical problem."
Southwest had delayed 1,820 flights or 43% of its schedule as of just after noon Tuesday, according to FlightAware. The airline has canceled only nine flights on Tuesday. Southwest says its workers "worked quickly to minimize disruptions.
Southwest called the problem "intermittent technology issues" in a social media post to customers. Several have taken to social media to complain about delayed flights.
"We apologize for any inconvenience this may cause, but we're hoping to get everyone going ASAP," the airline wrote in another social media post.
In December, Southwest canceled nearly 17,000 flights over the Christmas holiday due to bad weather and its crew-scheduling system becoming overwhelmed. Those cancellations cost the airline more than $1 billion and are being investigated by the Transportation Department.
CNN contributed to this report
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