WASHINGTON: The US Transportation Department said on Tuesday that it is opening an investigation into Delta Air Lines after the carrier canceled more than 5,000 flights since Friday as it struggles to recover from a global cyber outage that snarled airlines worldwide. While other carriers have been able to resume normal operations, Delta has continued to cancel hundreds of flights daily of a crew scheduling system.

Since Friday Delta has been canceling 30 percent or more of its flights daily through Monday, axing 418 flights on Tuesday, or 12 percent of its schedule as of 9:00 am and delaying another 356, or 10 percent, according to FlightAware, after canceling 1,150 on Monday. Transportation Secretary Pete Buttigieg said on Tuesday the investigation is to “ensure the airline is following the law and taking care of its passengers during continued widespread disruptions... Our department will leverage the full extent of our investigative and enforcement power to ensure the rights of Delta’s passengers are upheld.”

Delta did not immediately comment. Delta CEO Ed Bastian said Monday it would take the US carrier another couple of days before its operations recover. Since Friday, the carrier had canceled 4,000 flights as of Monday morning. A software update by global cybersecurity firm CrowdStrike triggered system problems for Microsoft customers, including many airlines, on Friday. Delta is widely respected for running a reliable operation.

Analysts say its on-time performance in terms of arrivals and departures has helped the airline cement its position as a premium airline. The issue has left customers fuming. Many complained they waited hours for assistance as the airline’s helplines were overwhelmed. Some were forced to rent cars, driving hundreds of miles to get to destinations, while others said they would have to wait days for new flights. In December, Southwest Airlines agreed to a record-setting $140 million civil penalty over the 2022 holiday meltdown that led to 16,900 flight cancelations and stranded 2 million passengers, resolving a USDOT investigation. — Reuters