Microsoft hits back at Delta after the airline said last month’s tech outage cost it $500 million

Microsoft joins cybersecurity software company CrowdStrike in the fight back against Delta Air Lines, which accuses the airline of canceling thousands of flights after a technical glitch last month.

A Microsoft lawyer said Tuesday that Delta’s core IT system is likely maintained by other technology companies, not Microsoft Windows.

“Your letter and Delta’s public comments are incomplete, inaccurate, misleading, and damaging to Microsoft and its reputation,” Microsoft attorney Mark Cheffo wrote in a letter to Delta attorney David Boies.

Cheffo said Microsoft was trying to understand “why other airlines were able to fully restore their operations so much faster than Delta.”

The comments reflect an escalating battle between the tech companies and the Atlanta-based airline.

Delta CEO Ed Bastian said last week that the global technology outage that began with a faulty upgrade of CrowdStrike to machines running Microsoft Windows cost the airline $500 million. Bastian threatened legal action.

Delta said Tuesday it has a long track record of investing in reliable service, including “billions of dollars in IT capital expenditures” since 2016 and billions more in annual IT costs. It declined to comment further.

CrowdStrike has also disputed Delta’s claims. Both CrowdStrike and Microsoft said Delta rejected their offers to help the airline recover from last month’s outage. Microsoft’s lawyer said CEO Satya Nadella emailed Bastian during the outage, but the Delta CEO never responded.