Delta Air Lines sued CrowdStrike over the July global technology outage that grounded thousands of flights and preceded a dayslong debacle for the air carrier.

The lawsuit accused CrowdStrike of gross negligence, alleging that the cybersecurity company is to blame for not only the outage but the rolling disaster that followed for the airline. In the lawsuit filed Friday in a Georgia state court, Delta called the IT breakdown “catastrophic,” citing $500 million in out-of-pocket losses and losses to future revenue.

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“CrowdStrike committed a series of intentional and grossly negligent acts that caused the global IT outage on July 19, impacting 8.5 million computers,” a Delta spokesperson said.

The Atlanta-based airline also accused the cybersecurity company of intentional misrepresentation, computer trespassing, breach of contract, and deceptive and unfair business practices. Delta is seeking monetary compensation for the damages.

CrowdStrike said it had aimed to reach a resolution that puts customers first, which it said Delta’s suit doesn’t accomplish.

“Delta’s claims are based on disproven misinformation, demonstrate a lack of understanding of how modern cybersecurity works and reflect a desperate attempt to shift blame for its slow recovery away from its failure to modernize its antiquated IT infrastructure,” a CrowdStrike spokesperson said.

The filing comes after weeks of finger-pointing between Delta and CrowdStrike, as well as legal threats by the airline.

The outage dealt a blow to Delta’s long-held selling point as a reliable airline with a fine-tuned operation that merited premium fares. It also struck at a critical moment for Delta: July 19, a Friday, was set to lead into Delta’s busiest weekend of the summer, with more than 90% of the airline’s seats booked.

Early on during the outage, Delta tried to stick to most of its flying schedule, hoping to take a more surgical approach to managing the tech problem rather than quickly moving to cancel more flights as the situation persisted.

Delta has said about 60% of its key applications are Windows-based, and the CrowdStrike outage left them inoperable. The tech breakdown left the airline struggling to dispatch planes and struck its crew scheduling system.