What Really Caused Southwest Airlines’ Holiday Meltdown?

The now-infamous meltdown of Southwest Airlines’ operations this holiday season cannot be blamed purely on the historic winter storm that’s swept much of the nation over the past week, insiders are saying.

The powerful Arctic front—which saw about 60 percent of the U.S. population placed under some form of winter weather warning or advisory—also impacted other U.S. airlines’ operations, but Southwest has had to cancel the highest number of flights and also been slowest to recover. While other airlines managed to get back on their feet shortly after Christmas Day had passed, Southwest’s cancellation rate actually increased.

While the historic nationwide storm may have sparked Southwest’s Christmas-week catastrophe, which saw nearly 16,000 flights cancelled and hundreds of thousands of travelers’ holiday plans thwarted, the larger problem lies with the airline’s antiquated IT infrastructure, according to insiders.

Multiple people familiar with the logistics of the debacle told CNN that the extreme weather situation pushed the carrier’s system for coping with “irregular operations” past the breaking point.

Southwest’s IT inadequacies mean that, when something goes amiss, multiple departments are left responsible for redesigning the airline’s flight schedule, as well as crew assignments, manually. This internal process works, “the vast majority of the time,” Southwest said in a statement. “The magnitude and scale of this disruption stressed our technology and processes, forcing a great deal of manual processing,” it explained.

Michael Santoro, vice president of the Southwest Airlines Pilots Association and a captain with the airline for over 13 years, told CBS News that Southwest’s outdated scheduling software cannot process crew reassignments beyond about 300 changes.

“The storm was the catalyst that started this whole event, but the major problem is that our scheduling IT infrastructure is outdated and can’t handle the massive cancellations that had to happen that day when the weather event occurred,” he said Wednesday. “You get this snowball effect where it can’t keep track of where pilots are, flight attendants are and airplanes are.”

“You end up with thousands of crew members having to call in and their wait times were hours just to talk to someone,” Brian Brown, president of Transport Workers Union Local 550, which represents Southwest dispatchers and meteorologists, told CNN. Santoro echoed, “Wait times for scheduling was over 4 or 5 hours to find out what our next assignment was.” He also noted that some crew members were forced to find hotel rooms or sleep in airports, if accommodations weren’t available in their area.

Southwest has said that it expects to resume normal operations from Friday, but this latest crisis isn’t its first in recent memory. “We’ve had a meltdown once or twice a year for the past several years,” he said. The pilots association said in a statement that the issue, “began many years ago when the complexity of our network outgrew its ability to withstand meteorological and technological disruptions.”

Santoro said that union officials have been raising their concerns for years, but that Southwest has yet to make the investment into its IT systems, some of which date back to the 1990s. “We’ve been harping on them since 2015-ish every year,” he said.

Southwest CEO Robert Jordan acknowledged the same in a Christmas Day message sent to employees. “Part of what we’re suffering is a lack of tools. We’ve talked an awful lot about modernizing the operation, and the need to do that. And Crew Scheduling is one of the places that we need to invest in,” he said. “We need to be able to produce solutions faster. We need to be able to communicate with each other where it doesn’t involve a phone call. Those things have been committed to and invested in, and you’re going to see improvements there—I just want you to know that.”