Southwest and other airlines are canceling thousands of flights in the US

Southwest Airlines canceled thousands of flights for Tuesday and Wednesday as the company struggled to recover from a deadly winter storm that stranded vacationers across the country.

The disruption to operations could last for several days. At many of the airports Southwest flies from, people have slept on the floor and waited in line for hours.

More than 2,900 U.S. flights were canceled and more than 2,400 others were delayed around 11:30 a.m. ET Tuesday, according to FlightAware, a flight tracking service. Most of the cancellations — more than 2,500 of them — came from Southwest, which had already canceled more than 60 percent of its flights for the day.

The airline has already canceled about 61 percent of its Wednesday flights and 14 percent of its Thursday flights, according to FlightAware. Southwest shares are down about 5 percent Tuesday morning.

Aviation experts said the storm had a disproportionate impact on Southwest because the company configures its network very differently than other major airlines like American Airlines and Delta Air Lines. Southwest, which has long prided itself on good employee relations, has also recently struggled with staffing shortages that have exacerbated tensions between management and workers, said Robert W. Mann Jr., a former airline executive. who now runs the consulting firm RW Mann & Company.

“Southwest clearly got the worst of it,” said Mr. Mann. “I have to think it was cultural more than anything.”

Southwest was in damage control mode late Monday and Tuesday morning, responding to angry and frustrated customers on Twitter. The airline apologized several times for the cancellations and offered help via direct message. The airline called its problems “unacceptable” and said it was doing everything it could to get crews where they were needed to restore their system.

“Our biggest problem right now is getting our crews and our planes in the right places,” Southwest spokesman Chris Perry said in an email.

The U.S. Department of Transportation said in a statement Monday it would investigate the problems at Southwest, adding it was concerned about the airline’s “unacceptable rate of cancellations and delays” and reports of poor customer service.

Henry Harteveldt, airline analyst at Atmosphere Research Group, said in an email that Southwest’s structure makes it “uniquely vulnerable to weather problems, particularly those as geographically widespread and as intense as this storm.”

“I can’t remember an airline having experienced such a massive operational problem as we are currently experiencing with Southwest,” he said.

Most airlines operate on a “hub and spoke” basis, with planes returning to a hub airport after flying to other cities — United hubs, for example, include airports in or near Newark, Houston, and Denver. Southwest uses a “point-to-point” approach, with aircraft typically flying from destination to destination without returning to a hub.

Hub-and-spoke airlines may close certain routes in inclement weather and resume operations when conditions improve. But Southwest can’t do that easily without disrupting multiple flights and routes, he said.

David Vernon, an airline analyst at finance firm Sanford C. Bernstein, said the scheme allows for higher use of planes in normal times but could have negative repercussions if things go wrong.

To make matters worse, Southwest doesn’t swap tickets with other airlines, so the airline can’t rebook passengers on other flights, Harteveldt said. The debacle could force the airline to “buy back” frustrated customers with deeper discounts or run more promotions, he said.

No single region or airport bore the brunt of the cancellations. As of Tuesday morning, more than 155 flights from Denver International Airport, or about 17 percent of outbound traffic, were canceled, and more than 115 flights, or about 38 percent, from Chicago Midway International were canceled. More than 100 flights were also canceled at Harry Reid International in Las Vegas, and similar numbers were reported at Baltimore-Washington International, Dallas Love Field in Texas and Nashville International in Tennessee.

It’s been almost a week since the winter storm began to devastate millions of travelers. The number of canceled flights began to rise last Thursday as airlines canceled more than 2,600 of them. The next day, nearly 6,000, or about a quarter of all US flights nationwide, were canceled. Almost 3,500 flights were canceled on Saturday, Christmas Eve, and slightly fewer flights were canceled on Christmas Day, at around 3,200.

In areas like Buffalo, where at least 28 people died and roads remained impassable after the worst winter storm in more than 50 years, the recovery is just beginning. A driving ban remained in place and snow was due to be final early Tuesday after accumulations of up to 49 inches end up. Many roads were not plowed and vehicles were left on the roads, Gov. Kathy Hochul said Monday.

Most of the power outages had been restored after more than a million customers were affected at the height of the storm, but thousands remained without power in Maine and New York early Tuesday, according to poweroutage.us.

Steve Lohr contributed to the coverage.