Many airlines were forced to cancel flights due to the weather, but Southwest was by far the leader in canceled flights. About 4,000 domestic U.S. flights were canceled Monday, according to the tracking website FlightAware, and 2,900 of those were Southwest’s.

According to flight tracking service Flightradar24, over 5,000 Southwest Airline flights were canceled for coming 48 hours.

In a statement, DOT said it will “probe whether these massive cancellations were controllable” and whether Southwest Airline is refunding or accommodating travelers in accordance with its customer service plan.

A Southwest spokesman said the airline is in contact with DOT Secretary Pet eButtigieg about the issue and referred to “requilibrate operations” in a phased manner.

“We are working to urgently address disruptions and reposition crews and our fleet, ultimately, to better serve all who plan to travel with us,” the spokesman added.

Virtually all US airlines have been affected amid the most severe winter storm, but many began to recover.

This is not the first time Southwest has had trouble recovering compared to other airlines.

In 2021, over the Indigenous Peoples’ Day weekend, Southwest had a similar collapse, with 2,000 flights canceled.

DOT touted a new consumer dashboard that allows travelers to see what benefits each airline provides, and is working on several regulations aimed at bolstering passenger protections, but they will take a few months to complete.

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