AUSTIN (Nexstar) — As thousands of Southwest Airlines passengers and employees are left stranded over the holidays, the airline’s union of flight attendants said they saw this coming.

“It’s the saddest day in Southwest Airlines history,” President of the airline’s flight attendants union Lyn Montgomery said. “All of this is generated by Southwest Airlines’ decisions. It’s not about Winter Storm Elliot. This is something that we actually have forecasted. We run the operation so hot that one day, it just isn’t going to be recoverable when we hit these irregular operations issues.”

Montgomery has been a flight attendant for the airline for 27 years. She blames the airline’s “archaic” technology that is insufficient to handle the airline’s present-day demand.

She said flight crews rely on telephone calls rather than an automated online system for reassignments and rescheduling.

“So if you have 1,200 changes at one time, that means a crew scheduling team has to reach out to 1,200 individuals. We have had flight attendants be on hold … anywhere from three hours to 17 hours just to wait to find out [their] next assignment.”

That schedule should slow for Montgomery and her peers, with Southwest Airlines planning to operate at about one-third of its typical schedule “for the next several days.”

The airline has already canceled nearly 8,000 flights through the first three days of a week when millions of Americans are traveling for the holidays.

“Our heartfelt apologies for this are just beginning,” the company wrote in a statement on Monday. “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.”

But its flight attendants union and the U.S. Department of Transportation suspect more than just the weather could be at fault.

The department said on Monday night it will “examine whether cancellations were controllable and if Southwest is complying with its customer service plan.”

Montgomery said Secretary of Transportation Pete Buttigieg granted her request for a one-on-one meeting with her Tuesday afternoon.

“I plan on letting him know that there needs to be some major changes,” she said. “The cards have fallen. It no longer needs any proof to know that there’s something systemically broken, and it’s up to Southwest executive leadership to take accountability and fix it.”