The Federal Aviation Administration lifted an order Wednesday morning to delay comm flights after a computer system failure.
Airlines resumed operations around 8 a.m. Central time.
The White House said there was no evidence of a cyberattack.
American Airlines at DFW Airport and Southwest Airlines at Love Field in Dallas said they were resuming normal operations but warned of delays and possible cancellations throughout the day.
“All customers who are traveling today, Jan 11, may rebook in the original class of service or travel standby (within 14 days of the original date of travel between and in accordance with our accommodation procedures) without paying additional charges,” Southwest said in a statement.
The flight-tracking website flightaware.com said more than 4,000 flights were delayed. Nearly 700 were canceled.
Previous update: 7:15 a.m.
Flights into and out of DFW, Love Field and other airports nationwide were grounded Wednesday morning.
A Federal Aviation Administration system failure forced flights to stay out of the air until 8 a.m. Central, the agency said.
The FAA reported an outage with the Notice to Air Missions, or NOTAM, which relays information to airports and pilots in real time, around 6 a.m. CT.
“The FAA is still working to fully restore the Notice to Air Missions system following an outage,” the FAA said in a statement. “The FAA has ordered airlines to pause all domestic departures to allow the agency to validate the integrity of flight and safety information.”
As of 7:15 a.m. Dallas time, more than 1,200 flights had been delayed nationwide.
More than 21,000 flights were scheduled nationwide Wednesday.
Dallas-based American Airlines said in a statement that it is “closely monitoring the situation, which impacts all airlines, and working with the FAA to minimize disruption to our operation and customers. We encourage customers to check aa.com for the latest flight information.”
American had delayed 292 flights and canceled 108 as of 7:15 a.m., flightaware.com reported.
President Joe Biden was briefed by Transportation Secretary Pete Buttigieg on Wednesday morning.
“I just spoke to Buttigieg. They don’t know what the cause is. But I was on the phone with him about 10 minutes,” Biden said. “I told him to report directly to me when they find out. Air traffic can still land safely, just not take off right now. We don’t know what the cause of it is.”