United States Alaska Airlines grounded all flights on Sunday due to an IT outage that disrupted its systems, the company announced, without disclosing specific details.

This marks the second time in just over a year the airline has halted operations fleet-wide.

“At approximately 8pm Pacific on Sunday (0300 GMT on Monday), Alaska Airlines experienced an IT outage that’s impacting our operations,” the carrier said in a statement. “We requested a temporary, system-wide ground stop for Alaska and Horizon Air flights.”

The Seattle-based, Alaska Airlines warned of continued disruptions throughout Sunday evening but did not offer further details.

The US Federal Aviation Administration did not immediately respond to requests for comment, though its status page indicated that all Alaska Airlines mainline flights were affected, along with a suspension of operations at regional carrier Horizon Air.

This marks the second major disruption for Alaska in just over a year.

In April 2024, the airline grounded its entire fleet over problems with software used to calculate aircraft weight and balance. That incident followed a high-profile midair blowout involving a door panel on a Boeing 737 MAX 9 operated by the carrier.

According to its website, Alaska Air Group operates 238 Boeing 737s and 87 Embraer 175s.

In June, Hawaiian Airlines—a subsidiary of Alaska Air Group—disclosed that some of its IT systems had been compromised in a cyberattack.

Alaska said at the time it was still assessing the financial impact.

The latest outage comes amid rising concern in the aviation sector over cyber threats, with tech firms like Google and Palo Alto Networks warning of increased targeting by the hacking group known as “Scattered Spider.”