System-Wide Technical Failure Halts Alaska and Horizon Air Operations for Hours, Leaving Passengers Stranded 

Seattle, WA – Alaska Airlines and its regional subsidiary, Horizon Air, grounded all flights across the United States on Sunday night, July 20, 2025, due to a significant system-wide IT outage that disrupted critical operations. The outage, which began around 8:00 PM Pacific Time (0300 GMT Monday), forced the airline to request a temporary ground stop from the Federal Aviation Administration (FAA), affecting over 200 mainline aircraft and an additional 45 planes operated by Horizon Air. 

The technical failure impacted the airline’s operating systems, halting check-ins, flight planning, and other essential functions. Passengers reported widespread delays, with some stranded on tarmacs for hours, unable to deplane or retrieve luggage. At Denver International Airport, traveler Grant Watts described waiting over two hours on a grounded aircraft before passengers were allowed to exit, with little communication from airline staff. Similar scenes unfolded at Portland International Airport, where frustrated travelers scrambled to rent cars or book alternative flights. 

Alaska Airlines announced the ground stop was lifted by 11:00 PM Pacific Time, approximately three hours after the outage began, allowing operations to resume. However, the airline warned of “residual impacts” throughout the evening, with delays and cancellations expected to persist as crews and aircraft were repositioned. “We sincerely apologize for the inconvenience and encourage guests to check the status of their flights before heading to the airport,” the airline stated on X. 

The cause of the IT outage remains unspecified, though it marks the second time in 15 months that Alaska Airlines has grounded its entire fleet due to technical issues. In April 2024, the airline halted operations over a problem with its weight and balance calculation system. The timing of Sunday’s disruption has raised questions about potential cybersecurity threats, as Microsoft reported “active attacks” on its server software used by businesses and government agencies on the same day. Alaska Airlines has not confirmed whether the outage is linked to these broader attacks, and the FAA has not yet commented on the incident. 

The aviation industry has faced increasing cybersecurity challenges, with recent incidents affecting carriers like Canada’s WestJet in June and Australia’s Qantas in July, where hackers accessed millions of customers’ personal data. Alaska Airlines, which serves over 44 million passengers annually across 120 destinations, operates a fleet of 238 Boeing 737 aircraft and 87 Embraer 175 jets through Horizon Air, making such disruptions particularly impactful. 

Passengers affected by the outage were advised to retain receipts for hotels and alternative travel arrangements for potential reimbursement. The airline has not provided a timeline for full service restoration but continues to update its social media channels with the latest information. As the industry grapples with escalating digital vulnerabilities, this incident underscores the critical need for robust technological infrastructure in aviation.