Southwest Airlines said that its computer problems were mostly fixed, but warned customers booked on Thursday flights to check their flight's status online -- and get to the airport early where long lines were forming.
Some flights were arriving and departing on time, but others were canceled Thursday morning at Sacramento International Airport. Longer than usual lines formed at the Southwest ticket counters before the sun came up.
Among the flights canceled Thursday morning on Southwest were arrivals from Los Angeles, San Francisco and Orange County. A departure to Las Vegas was also canceled.
On Wednesday, Sacramento International Airport officials reported that seven flights have been canceled and 51 flights delayed because of Southwest Airline's nationwide computer outage.
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The airline has already canceled more than 220 flights on Thursday, the Associated Press reported.
The airline said "most systems are back online" after problems that began with an outage Wednesday afternoon and continued intermittently well into the night.
"We know we disappointed customers today. We are really, really sorry about that," spokeswoman Linda Rutherford said in a video that the airline posted Wednesday night. "That is unacceptable to us."
Southwest officials said they had not identified the cause of the outage. Several of the airline's technology systems were affected for several hours. The airline briefly held up all departing flights on Wednesday, and its website and electronic check-in systems failed.
After a similar outage last October resulted in 800 delayed flights, Southwest blamed a faulty software application.
In Sacramento, customers who do not have bags to check can avoid long lines at the Terminal B ticket counters by printing out their boarding passes on any of the self-serve kiosks on Level 2 of Terminal B, officials said.