CHICAGO (AP) -- Southwest Airlines expects some lingering delays Saturday morning after a system-wide computer failure caused it to ground 250 flights for nearly three hours late Friday night.
Full service was restored just after 2 a.m. EDT Saturday, but the Dallas-based airline is still working to clear a backlog of flights and reposition planes and crew.
The airline -- the country's largest domestic carrier -- canceled 43 flights Friday night and another 14 Saturday morning.
Southwest is the latest airline to ground flights because of a large computer outage. But its problem was minor compared to those experienced by two competitors -- thanks in part to its late-day timing.
In April, American Airlines grounded all of its flights nationwide for several hours due to computer problems. The airline ultimately canceled 970 flights. And last year, United Airlines had two major outages: one in August delayed 580 flights; another in November delayed 636 flights.
The problem was detected around 11 p.m. EDT Friday, Southwest spokesman Brad Hawkins said. It impaired the airline's ability to do such things as conduct check-ins, print boarding passes and monitor the weight of each aircraft. Some flights were on the taxiway and diverted back to the terminal, Hawkins said. Flights already in the air were unaffected.
Most of Southwest's cancelations Friday night were in the western half of the country, according to airline spokeswoman Michelle Agnew. Saturday's cancelations were scattered across the U.S. They included planes leavings from Minneapolis, Chicago, Phoenix, Denver and San Diego, according to flight tracking service FlightAware.
Southwest flies an average of 3,400 flights each day.
Agnew said in an email Saturday morning that the airline's technology team is "still working to confirm the source of the issue."
Shortly after 2 a.m., Southwest posted on its Twitter page that "systems are operating and we will begin work to get customers where they need to be. Thanks for your patience tonight."
Agnew said the computer system was "running at full capacity" by early Saturday. Before that, though, officials used a backup system that was much more sluggish.