Alaska Airlines and its Horizon Air affiliate canceled 95 flights Saturday because a computer system used for flight planning failed.
The outage lasted intermittently for about seven hours and resulted in the two airlines scrapping about 12 percent of their combined schedule before technicians fixed the system, which returned at 10 a.m. Pacific time.
Company spokesman Paul McElroy said many other flights were delayed, and customers had trouble getting flight-status updates on the airlines' website because of the outage.
McElroy said stranded passengers would be rebooked on later planes or put on other airlines and Alaska will consider adding flights. He said passengers will not be charged a flight-change fee.
The airline declined to say how many passengers were affected.
Alaska Airlines, which canceled 54 flights, uses versions of the Boeing 737 with roughly 124 to 172 seats, according to airline seating chart websites. Horizon, which canceled 41 flights, uses smaller turboprop planes.
McElroy said the company was going through a routine upgrade of its computer system when something went wrong.
Seattle-based Alaska Airlines flies to cities in the U.S., focusing on the West Coast, and to Canada and Mexico. Alaska and Horizon are owned by Alaska Air Group Inc.