Frustrated Southwest pilot and union rep says the airline's flight meltdown was caused by outdated scheduling software

Southwest Airlines blamed its problems on the busy holiday weekend and the powerful winter storm, but said on Tuesday that its antiquated scheduling system was to blame.

The carrier canceled almost all of its flights on Monday. More than 60 percent have been canceled for a total of more than 2,400.

Southwest told Insider that it had had issues with its scheduling tools and that caused a scheduling issue.

Southwest is the largest carrier in 23 of the top 25 travel markets in the US and was fully staffed for the upcoming holiday weekend when severe weather swept across the continent. The operational conditions forced daily changes to our flight schedule at a volume and magnitude that still has the tools to recover the airline operating at capacity.

While the winter storm was a catalyst for the disruptions, the company's outdated scheduling software created the snowball, according to Captain Mike Santoro.

The system that tracks the company's pilots and flight attendants got so busy that it was not able to keep up.

He said that it was difficult for the schedulers to put it back together after they got out of position. The software isn't keeping track of us.

He explained that one flight had two pilots and three flight attendants assigned to it but needed one more flight attendant to legally fly.

The flight attendants were being flown to another city for an assignment but were also ready, willing, and able to work that flight as well.

The company canceled the flight when they didn't need to because the system didn't know they were on that plane.

scheduling didn't know that the flight attendants were in the back of the plane.

In an interview with Texas news outlet KHOU, the president of Southwest's flight attendant union pointed to the scheduling software as one of the reasons the carrier failed to recover from the storms.

United Airlines and American Airlines mostly avoided this. Their systems are modern and can handle the workload more quickly than Southwest's can. Montgomery told KHOU that flight attendants use a system that relies on phone lines. The system can get so jammed that crews are forced to wait on hold for hours.

Southwest will continue to operate a reduced schedule in order to recover its operations.

The senators pointed to internal failures at the company and said passengers should be compensated for the disruptions.

Southwest can't avoid paying passengers by blaming winter storms. Southwest executives have acknowledged that the mass cancellation was due to the failure of its own internal systems. Southwest should compensate passengers for those canceled flights.