Southwest Airlines is experiencing some residual delays after problems with its computer system Wednesday afternoon caused "significant flight delays" at airports across the country, including Baltimore-Washington International Thurgood Marshall Airport, the airline said.
Hundreds of travelers waited in the terminal to depart BWI on Wednesday, where Southwest is the largest carrier by far — responsible for more than two-thirds of the flights.
On Thursday morning, more than 221 flights were canceled, Southwest officials said in a statement.
"There were [lines] earlier this morning" said Jonathan Dean, a BWI spokesman said just before 9 a.m. Thursday. But just before 9 .am., he said "things are moving."
He couldn't say how many flights from BWI are among those canceled Thursday morning.
Some pictures posted on social media early Thursday showed large groups waiting along ticket counters. A reporter with WJZ-TV captured former Gov. Martin O'Malley in line, tweeting "Southwest backups even include Former Gov's!"
Most of the airline's systems were back online Wednesday night after outages, but a statement warned that "recovery will take some time. We expect some cancellations and delays as we position aircraft and crews."
"I'd like to know how a company as big as Southwest can have their whole server go down," said Laurie Earl, who was traveling home to Salt Lake City after visiting her son in Glen Burnie. "Where's the backup plan?"
Dean said Wednesday afternoon that he did not know specifics of the problem, or how many flights into and out of BWI were affected.
According to the flight tracker FlightAware.com, 74 flights were delayed and three were canceled at BWI on Wednesday as of 7:15 p.m. — the majority of them Southwest flights. Nationwide, Southwest had canceled 17 flights, and delayed more than 600 as of 9 p.m., according to FlightAware.com.
"We apologize that our computer system is down," the airline announced in the late afternoon at BWI. "Again, this is a computer issue out of our control."
For about three hours, visitors to Southwest.com couldn't buy tickets, check in for flights or check their flight's status. The site appeared to be working again by late afternoon. Airline officials said some difficulties could last into Thursday. Southwest announced it would offer flexible accommodations to reschedule trips.
The line to check-in with Southwest at BWI stretched through the terminal and folded back on itself. Police patrolled with dogs and rifles.
"When we pulled up, we were like what are all the police here for?" said Bree Stevens, of Vienna, Va., bound for Utah with her husband and their four children. "I was freaking out, like, 'Uh, honey? I don't know if I want to get on an airplane today.'"
Travelers sighed, sat on their luggage, rested their chins on palms.
"I almost have to take her out again," Stacey Daily said of her leashed Italian greyhound, Gi-Gi.
Daily had been waiting two hours with her dog, husband and their two children to leave for Oakland, Calif. Their flight was scheduled to depart in minutes. "I don't want to spend the night in the airport with two kids and a dog," she said.
The airline said it "began experiencing intermittent performance issues earlier this afternoon with multiple technology systems as a result of an outage."
Southwest apologized to its customers and said it had a team of experts "working diligently to fully resolve the technical issues," and its systems were "gradually coming back online."
Resuming normal operations "will take time," the airline said.
Airlines have sprawling, overlapping and complicated technology systems, and even brief outages can strand thousands of passengers for hours.
Last October, an outage caused about 800 Southwest flights to be delayed and forced employees to issue tickets and boarding passes by hand. The airline blamed a software application, and it recovered in about a day. United Airlines and American Airlines both had computer problems last summer but fixed the problems within a day.
Dallas-based Southwest Airlines carries more passengers within the United States than any airline. However, it is far smaller than American, Delta and United when international traffic is included.
In the BWI terminal, 3-year-old Journey Waters of Baltimore rode a duffel bag dragged by her father. Mitch Waters was taking his family on vacation to Disney's Blizzard Beach in Orlando, Fla.
"We weren't expecting this," he said, gesturing to the crowd.
Then another armed policeman walked past.
"Man," Waters said, "they're not playing no games out here."
Baltimore Sun reporter Jessica Anderson and The Associated Press contributed to this report.