Southwest Airlines apologized as it canceled more than 2,500 flights scheduled for Tuesday in the fallout of a winter storm that snarled much of the U.S.

Southwest’s cancellations, which include more than 60 percent of its schedule, comprise the majority of the 2,867 U.S.-based flights canceled on Tuesday, according to FlightAware.

Most other major airlines have largely recovered from a weekend filled with flight cancellations and delays, but Southwest announced it will only fly roughly one-third of its schedule for the next several days.

“With consecutive days of extreme winter weather across our network behind us, continuing challenges are impacting our Customers and Employees in a significant way that is unacceptable,” Southwest Airlines said in a statement on Monday. “And our heartfelt apologies for this are just beginning.”

The airline said it is repositioning its crews and planes to address the wide-scale disruption.