By 3:30 p.m. Eastern time, airlines canceled nearly 2,500 U.S. flights on Friday, according to flight-tracker FlightAware. Airlines were working to recover from an overnight global technology outage.
The outage was caused by a recent update undertaken by cybersecurity firm CrowdStrike and affected Microsoft Windows users of its tool.
The outage has impacted airlines worldwide. There have been 4,000-plus cancellations around the world.
Atlanta, where Delta is by far the largest carrier, was the airport with the most U.S. cancellations on Friday, with nearly 300. That amounts to 24% of the Atlanta schedule.
According to airline data provider Cirium, there were more than 27,000 departures scheduled for Friday from U.S. airports; approximately 8.8% have been canceled.
There have also been 8,000-plus delayed U.S. flights.
Delta had canceled the most flights with 836, or 22% of its schedule, according to FlightAware. American and United had each canceled more than 350 flights.
Conversely, Southwest and Alaska flyers should feel fortunate. Each had canceled just four flights, according to FlightAware.
In a statement on Friday morning, Delta said the technology disruption had forced it to pause its global flight schedule overnight, but that operations had resumed.
United also paused all departures overnight before resuming them in the morning. The carrier said the software disruption impacted separate systems, such as those used for calculating aircraft weight, checking in customers and phone systems in call centers.
American, too, halted its operation overnight, before restarting at 5 a.m. Eastern time.
United and Delta have issued waivers, allowing for rebookings without change fees or fare differences for impacted travelers.
American has waived change fees, but the waiver makes no mention of fare differences being waived.
The U.S. Department of Transportation said that the DOT views CrowdStrike-related delays and cancellations as controllable. That means airlines must adhere to the customer service commitments for flight disruptions.
Flyers and travel advisors can view those commitments at the DOT Airline Customer Service Dashboard.