(NEXSTAR) – Despite the worst of the winter weather being over by Tuesday, the travel nightmare for Southwest Airlines was far from over.

As of Tuesday morning, 63% of the airline’s flights were canceled nationwide, according to FlightAware. Another 8% were delayed.

“This is the largest scale event that I’ve ever seen,” Southwest CEO Bob Jordan told the Wall Street Journal Monday.

The mass cancellations started with the blizzards, high winds and sub-zero chills that affected much of the Midwest and the Northeast. The bad weather in part of the country triggered a snowball effect that had travelers in sunny Southern California and Florida stranded as they tried to get home after the holiday weekend.

The problem, according to Southwest, is the areas that saw the worst weather are most dependent on the airline. “We were fully staffed and prepared for the approaching holiday weekend when the severe weather swept across the continent, where Southwest is the largest carrier in 23 of the top 25 travel markets in the U.S.,” the airline said.

That created problems in areas not even impacted by bad weather.

If a Buffalo-to-Los Angeles flight is canceled because of the blizzard in New York, for example, and that crew was planning to fly to Phoenix next, that second leg might also be canceled if there’s no one to fly the plane and assist with passengers.

A Southwest told NPR there were also issues rescheduling employees and “connecting flight crews to their schedules,” making it harder to bounce back from delays and cancellations quickly.

As the airline works to recover, Southwest said it is planning to fly “roughly one third of our schedule for the next several days.”

Travelers trying to rebook flights out of some airports are reporting there are no options available until Dec. 31 or early 2023.

Nexstar contacted Southwest for an estimate on when operations will return to normal, but did not hear back by publication time.

The U.S. Department of Transportation said it will be looking into the thousands of flights canceled by Southwest to see if the company is complying with the promises outlined in its customer service plan.