Delta Air Lines was slow to restore normal operations after last week’s largest-ever information technology outage.

As previously reported by The Dallas Express, the global outage caused a tidal wave of flight cancellations and delays. A malfunction inside an update for Microsoft Windows systems launched by the cybersecurity firm CrowdStrike forced the shutdown of Microsoft’s cloud computing services.

While many airlines have managed to come through the other end of the nightmare earlier this week, Delta wasn’t so lucky, resulting in hundreds of passengers stuck in travel limbo.

The Atlanta-based airline saw the highest number of flight cancellations during the outage, which triggered a Department of Transportation investigation into Delta passengers’ complaints.

“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. All airline passengers have the right to be treated fairly, and I will make sure that right is upheld,” wrote U.S. Secretary of Transportation Pete Buttigieg via X earlier this week.

Delta has issued single-use travel waivers to make it easier for customers to reschedule their trips and waived fare differences until July 28. Nevertheless, there have been alarming reports of passengers waiting hours to speak with Delta’s customer service representatives, according to Fox 4 KDFW.

The airline’s struggles to resume normal operations appeared to be centered at its Atlanta hub, where issues with crew coordination and a backlog of lost bags have been most severe. There has been a ripple effect on other airports, including Dallas-Fort Worth International Airport.

“They took me off the flight. They said there wasn’t a crew. After there wasn’t a crew, they still took my bag. They didn’t give us our bags back,” a Delta passenger named Toki Wright told Fox 4 at DFW Airport.

Wright had planned trips to Las Vegas and Dallas with his daughter and was supposed to be back in Boston on Wednesday.

Since the outage began on July 19, Delta has canceled more than 5,500 flights, including at least 700 on Monday alone, according to flight data provider Cirium.

Delta and its regional partners were responsible for about two-thirds of all global flight cancellations on Monday, almost all of which occurred within the United States.

The situation nevertheless appears to be clearing up.

On July 25, DFW Airport had 13 canceled flights and 401 delayed flights, although Delta only accounts for nine of the delayed flights. By comparison, the airline represented 193 of the 323 delayed flights at Hartsfield-Jackson International in Atlanta that same day, but also none of its 11 canceled flights.

Overall, the airline accounts for 12% of all delayed flights within, from, or into the United States on July 25 — a total of 452.

Delta CEO Ed Bastian successfully arrived in Paris for the Olympic Games on Wednesday. The airline is an official sponsor of the U.S. Olympic team.

“Ed delayed this long-planned business trip until he was confident the airline was firmly on the path to recovery,” Delta said in a statement to CNN. “As of Wednesday morning, Delta’s operations were returning to normal. Ed remains fully engaged with senior operations leaders.”