01:20 PM EDT, 07/23/2024 (MT Newswires) -- Delta Air Lines ( DAL ) said Tuesday it is cooperating with the US Department of Transportation's investigation into the carrier's handling of thousands of flight cancellations in the wake of Friday's global technology outage.

The company canceled another 460 flights by afternoon on Tuesday, adding to the roughly 5,000 cancelations from Friday through Monday, according to data from FlightAware. It had delayed 779 flights on Tuesday by afternoon.

Transportation Secretary Pete Buttigieg said in a post on X, formally known as Twitter, Tuesday that the department has opened an investigation into Delta's handling of flight disruptions. Previously, he posted that the DOT had received hundreds of customer complaints amid "unacceptable customer service conditions" at Delta.

The DOT wants to "ensure the airline is following the law and taking care of its passengers during continued widespread disruptions," Buttigieg wrote Tuesday. "All airline passengers have the right to be treated fairly, and I will make sure that right is upheld."

In a statement emailed to MT Newswires, Delta said it received the DOT's notice of investigation and is fully cooperating. Delta teams are "working tirelessly to care for and make it right for customers impacted by" CrowdStrike's ( CRWD ) faulty Windows update, according to the company.

"We remain entirely focused on restoring our operation," the company said.

On an X thread posted Sunday, Delta told customers that canceling a flight is "always a last resort and not taken lightly." The carrier said it extended the travel waiver for customers with travel booked from July 19-21 for them to make a one-time change to their itinerary and was also offering reimbursement for hotel, meal and ground transportation expenses incurred during the operational disruption.

In a video posted on Delta's intranet on Monday, Chief Executive Ed Bastian told employees that "it's going to take another couple of days before we're in a position to say that ... the worst is clearly behind us," according to the transcript shared by the airline.

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