SEATTLE — A second major Alaska Airlines IT outage in four months canceled more than 400 flights and stranded 49,000 travelers; the carrier orders a full technology audit.

SEATTLE — For the second time in four months, Alaska Airlines passengers found themselves grounded when the carrier’s information-technology systems failed. Thursday’s breakdown at the airline’s primary data center froze operations for about eight hours, forcing the cancellation of more than 400 flights on Thursday and Friday and disrupting the travel plans of 49,000 customers.