As the Department of Transportation opened an investigation into Delta Air Lines Tuesday after it canceled thousands of flights as a result of Friday’s global IT outage, the carrier’s president apologized.

“I just like to start with an apology, as you know we were impacted dramatically by the CrowdStrike situation that happened at the end of last week,” said Glen Hauenstein, president of Delta Air Lines, onstage at the Global Business Travel Association convention in Atlanta.

He continued: “We have been working around the clock to try and recover. Unfortunately, our recovery [has been] a little bit more sluggish than some of our competitors, who also had CrowdStrike.”

The airline, Hauenstein said, is “painfully aware” of its slow comeback after the technology failure. The Delta executive did not expand upon why the carrier has been so slow to recover.

As of midday Tuesday, FlightAware reported the airline had canceled more than 460 flights – the fifth day since the initial tech glitch.

And Tuesday morning, United States Secretary of Transportation Pete Buttigieg announced the DOT investigation on X.

“.@USDOT has opened an investigation into Delta Air Lines to ensure the airline is following the law and taking care of its passengers during continued widespread disruptions,” Buttigieg wrote. “All airline passengers have the right to be treated fairly, and I will make sure that right is upheld.”

The Delta flight disruptions likely aren’t over, Hauenstein said. “We should be well on our way back to normal operations with a target of being fully [back] by Thursday or Friday.”

For Delta, the experience has been trying but one Hauenstein anticipates it will learn from once the airline fully recovers. 

“We [talk] a lot about technology, we talk a lot about AI and this is where technology has not actually been helpful for us … It’s been actually a hindrance,” he said.