Sunday update: 6,500 flights cancelled due to computer glitch

Mass flight cancellations disrupted U.S. airports for a third straight day Sunday, as the lingering fallout from a technical glitch Friday affecting Microsoft Windows clients caused IT infrastructure outages worldwide and disrupted many airline operations.

Delta Air Lines and United Airlines again canceled hundreds of flights Sunday as both carriers continued to try to resume operations following problems caused by a third-party vendor late last week.

The problems led to crowded terminals at airports across the country this weekend, with long, winding lines of travelers waiting to speak to customer service, and images of passengers sleeping on the floors of airport concourses.

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By late Sunday morning, airlines had canceled more than 1,000 flights in the United States.

According to data from flight tracking site FlightAware, Delta was the hardest-hit airline with more than 500 cancellations Sunday, or about 13% of its business. United came in second with 253 cancellations Sunday, or about 8% of its schedule.

In total, airlines have canceled more than 6,500 flights in the United States since Friday’s disruption, including nearly 3,000 on Delta, according to data from FlightAware.

Delta Airlines

In a statement Saturday, the Atlanta-based carrier said it was still getting operations back on track after the computer outage at Austin-based Crowdstrike forced it — and several other U.S. airlines — to temporarily suspend flights Friday.

Delta extended its pause on unaccompanied minor flights through Tuesday (July 23) and extended travel waivers that allow passengers more flexibility to change their itineraries — a move taken by other carriers, including United.

United Airlines

In its latest update Saturday, United told TPG that its customer service call systems had been fully restored and noted that most technology systems were back up and running — but warned of further cancellations and delays likely over the weekend.

U.S. flight cancellations on Saturday were down 37% from Friday, according to data from FlightAware, but still topped 1,600 for the day, led by Delta at 1,200.

Delta and United’s major hubs were the hardest-hit U.S. airports this weekend, from Hartsfield-Jackson Atlanta International Airport (ATL) to Minneapolis-St. Paul International Airport (MSP), Denver International Airport (DEN) and Newark Liberty International Airport (EWR) — among others.

What do airlines owe you after a cancellation or delay?

Although the issues originated with a third-party vendor, and not the airlines directly, the U.S. Department of Transportation considers these cancellations and delays to be “controllable” — in other words, the airline’s responsibility — an agency spokesperson told TPG Friday.

That means the promises airlines make, as outlined in the airlines’ customer service dashboard, will apply. Here’s what each airline told the DOT they would guarantee after a cancellation or significant delay.

Other important resources:

Transportation Secretary Pete Buttigieg took to social media Saturday to reiterate the agency’s reimbursement policies.

“I’ve heard that some airlines are only offering flight credits,” Buttigieg wrote on X, formerly Twitter. “Let me be clear: you have the right to get your money back quickly if your flight is canceled and you don’t rebook.”

An outlier in 2024

The operational disruptions over the past 48 hours come during a year that has been largely without a major air travel crisis.

Between January 1 and July 18, U.S. airlines canceled 1.3% of flights, according to FlightAware. That compares to a cancellation rate of 2.6% during the same period in 2022.

Delta specifically touted its operational reliability during the carrier’s second-quarter earnings call on July 11.

“Our operations this year have been the best in the industry on every measure, month after month,” CEO Ed Bastian said at the time. The carrier has performed well in recent J.D. Power airline rankings and TPG’s 2024 Best Airlines report, thanks in part to its operational reliability.

“Unexpected disruptions like these are difficult to manage and do not reflect the operational reliability and experiences customers have come to know and expect from us,” the carrier said Saturday.

The industry’s most recent large-scale operational issues include a multi-day incident at United last summer that prompted the carrier to step up its work with the Federal Aviation Administration on operations at Newark… and an FAA computer outage in January 2023 that led to the first nationwide grounding since Sept. 11, 2001. The latter incident came just days after Southwest Airlines’ operational disaster during the 2022 holiday season.

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