Delta's operational difficulties, which was precipitated by the July 19 CrowdStrike outage, has continued into a fifth day.
The airline canceled 480-plus mainline flights on Tuesday, accounting for 13% of its schedule, according to flight-tracker FlightAware. In addition, 41% of Delta's schedule was delayed.
Cancellations by Endeavor, a wholly-owned subsidiary of Delta that operates a portion of Delta Connection regional flights, had moderated from previous days; cancellations accounted for 4% of its Tuesday schedule.
In its latest update about recovery efforts, Delta said that more than half of its worldwide IT systems are Windows-based, and that the CrowdStrike failure required the airline to manually repair and reboot affected systems.
Additional time was also required for various applications to synchronize and start communicating with each other, Delta said on Monday.
"Delta's crews are fully staffed and ready to serve our customers, but one of Delta's most critical systems -- which ensures all flights have a full crew in the right place at the right time -- is deeply complex and is requiring the most time and manual support to synchronize," the airline said.
Delta reiterated that it will issue SkyMiles points or travel vouchers to impacted customers, with amounts based on affected travel. The airline also said it will reimburse customers who have incurred hotel, meal and ground transportation expenses while in transit.
Delta customers whose flights have been canceled or significantly delayed can also cancel their travel and request a refund at delta.com/refund.
Delta customer Akhtar Nawab, who holds the top SkyMiles loyalty status of Diamond Medallion, said such measures aren't good enough. He explained that on July 20 it took him 14 hours to travel on Delta from Southern California's Orange County to New York LaGuardia via Minneapolis due to delays. His flight on Tuesday from LaGuardia to Norfolk, Va., for a family vacation was also delayed multiple times. Delays of his father's flight to Norfolk from Louisville, Ky., via Atlanta led the family to cancel that itinerary and rebook on Southwest for Wednesday.
"It's insane that they're not prepared at all for this," Nawab said. "Had I known that this would linger for this long, I think I would have rebooked us on a different airline."
Nawab also said that agents at Delta's specialized Diamond Medallion call center didn't have enough information to be helpful.
In its Monday afternoon update, Delta said that it had notified customers about delays and cancellations via text and through the Fly Delta app, and has offered rebooking options that can be managed online. But the airline also acknowledged that its digital tools have been overwhelmed, causing performance challenges.
Travel Weekly has reached out to Delta for further explanation on why it does not have redundant systems in place that would ease recovery from a third-party outage like the CrowdStrike one. Delta has also been asked how much longer it expects it will take to reset and recover its operation.
The airline's travel waiver related to the disruption is set to expire at the end of the day on July 23. Under the waiver, fare differences will be waived for rebookings for travel beginning by July 28.
Despite Tuesday's spate of cancellations, Delta appears to be making progress on a reset. The carrier canceled 1,159 mainline flights on Monday. Tuesday cancellations are on a slower pace.