The Department of Transportation has ended its investigation of the operational meltdown that beset Delta Air Lines in July 2024.
The failure, during which Delta canceled approximately 7,000 flights and delayed more than 10,000 over the course of five days, was precipitated by a software update by cybersecurity provider CrowdStrike that crashed Microsoft Windows operating systems around the globe.
"After review, it was determined that Delta's passengers received prompt refunds, adequate baggage assistance, and appropriate assistance for passengers with disabilities," the DOT said in an emailed statement. "Because the president has directed his administration to ensure enforcement actions serve the public interest, the matter was closed with direction given to Delta to provide adequate customer service assistance including timely notification of the right to seek a refund."
In its own statement, Delta said its top priority is to take care of its employees and customers.
"We are grateful to the Department of Transportation for recognizing the catastrophic circumstances we faced as an industry during the unprecedented outage and its dismissal of the investigation citing how we cared for customers, which included millions of dollars in refunds, hotels, food and baggage assistance," Delta said.
Delta sues CrowdStrike
The same CrowdStrike software update also forced the other major U.S. airlines to halt operations, but they recovered faster. American, for example, had largely recovered its operation by the evening of the faulty update and had only 51 mainline flight cancellations the following day.
Delta explained at the time that 60% of its mission-critical applications, including redundant backup systems, rely on Windows, and that during its recovery it had to physically reset 40,000 servers -- a bigger lift than any other airline.
Delta sued CrowdStrike in a Georgia court over the matter in October 2024, alleging the faulty software update cost it more than $500 million. The case is ongoing, though the court dismissed the most serious of Delta's claims in 2025.