Hundreds of Southwest Airlines flights have been delayed as the carrier deals with winter weather and a computer outage.
The outage occurred early Friday and grounded Southwest flights around the country for nearly an hour.
A spokesman for the Federal Aviation Administration says Southwest had a problem with a system that transmits flight plans to the FAA.
Southwest said in a statement that it suspended operations for about 50 minutes early Friday to "ensure performance" of software systems that were upgraded overnight. Spokesman Chris Mainz said early morning flights on the East Coast were delayed by an average of 40 minutes, but the matter didn't cause any flight cancellations.
By midmorning Central time, about 600 Southwest flights had been delayed, 15 percent of Southwest's schedule and far more than any other U.S. carrier, according to FlightAware.
The airline said some of the delays are also due to winter weather.
The outage and winter weather come as Southwest reports a higher than normal number of planes taken out of service for maintenance. That's causing tension between the airline and the aircraft mechanics' union.