A staffing shortage may have led to Southwest’s holiday travel debacle that saw over 70% of flights canceled on Monday, as previously reported by The Dallas Express.

Southwest saw an unusually high number of employee absences and declared a “state of operational emergency” at the Denver Airport, according to a December 21 message to ramp workers seen by Bloomberg News.

The company is still working to get back to normal operations, with 60% of its Wednesday flight schedule and 58% of its trips for Thursday canceled, according to FlightAware.

Southwest CEO Bob Jordan apologized in a Tuesday video, saying the company reduced its schedule to reposition aircraft and crews.

“We’re optimistic to be back on track before next week,” Jordan said.

Analysts at Citigroup estimate the carrier’s response to the storm that engulfed much of the country could have a 5% drag on Southwest’s fourth-quarter profits.

Bloomberg News was able to obtain management messages to Southwest employees, which the outlet said highlighted how the airline struggled as the “systems used to coordinate a vast network of airplanes, destinations, and flight crews were first overwhelmed and then failed to recover.”

Jordan said, “Part of what we’re suffering is a lack of tools.” He also noted that the company’s scheduling system is an area in need of investment.

“We need to be able to produce solutions faster, and we need to be able to communicate with each other where it doesn’t involve a phone call,” Jordan added.

The Department of Transportation is investigating “whether cancellations were controllable and if Southwest is complying with its customer service plan,” the department tweeted on December 26.

Bloomberg’s report suggests Southwest was well aware of issues ahead of Christmas.

On December 21, severe weather was already disrupting Southwest’s operations in Denver, limiting the number of flights the airline could handle safely, Chief Operating Official Andrew Watterson reportedly said in an internal message.

Southwest also suspended operations at Chicago’s Midway International Airport, meaning both locations would have fewer flights shuttling crews between their home bases and assignments, Watterson said.

On December 23, 90% of Southwest’s routes were affected by weather, but Watterson said the company had taken steps to position itself for fewer cancellations on Christmas Eve.

“As long as there’s not another disruption, we’ll start the day in a much better position,” Watterson claimed.

That did not happen, as the airline faced weather disruptions and a refueling glitch. Southwest’s base at Dallas Love Field was loaded with parked aircraft to ease congestion at northern airports overwhelmed by frigid temperatures.

This left Southwest “no choice but to implement additional cancellations,” Watterson said.

Southwest CEO Jordan spoke with Transportation Secretary Pete Buttigieg, who said the mishap was more than just a weather event.

“This has clearly crossed the line from what’s an uncontrollable weather situation to something that is the airline’s direct responsibility,” Buttigieg argued on NBC Nightly News.

Senate Commerce Committee Chair Maria Cantwell affirmed Buttigieg’s position.

“The problems at Southwest Airlines over the last several days go beyond weather,” Cantwell said in a statement. “The committee will be looking into the causes of these disruptions and its impact to consumers.”

Cantwell also said consumers need more robust protections, including an updated consumer refund rule.

Sens. Ed Markey of Massachusetts and Richard Blumenthal of Connecticut posited the airlines should compensate customers for their tickets and spoiled holiday plans.