Alaska Airlines temporarily grounded its entire mainline fleet and those of its regional subsidiary Horizon Air late Sunday after a software outage crippled key operating systems. The carrier asked the U.S. Federal Aviation Administration for a system-wide ground stop at about 8 p.m. Pacific time, halting departures across its network. The restriction was lifted roughly three hours later, around 11 p.m., after the airline said the IT problem had been resolved. Flight-tracking service FlightAware logged at least 50 cancellations and 46 delays by early Monday, and the Seattle-based carrier warned of “residual impacts” as aircraft and crews are repositioned. Customers were advised to confirm flight status before heading to airports. The episode marks the second fleet-wide grounding for Alaska in just over a year; a weight-and-balance software glitch prompted a similar stoppage in April 2024. Alaska Air Group operates 238 Boeing 737 aircraft and 87 Embraer 175 regional jets. The company has not disclosed the cause of the latest outage.