Alaska Airlines is recovering from a computer networking problem that threw its passenger check-in system offline early Monday morning.
Operations slowly were returning to normal Monday afternoon after a fiber-optic outage shut down its ticketing system for five hours, cancelling flights in Seattle and Los Angeles and causing delays across the airline's 64-airport network.
"Sprint internet service was disrupted at 7:30 a.m. and was restored about noon. As of noon, the two airlines had canceled 70 flights, affecting more than 6,000 passengers," the company said in a statement. "Alaska and Horizon plan to pre-cancel some flights scheduled to depart between 2 and 5 p.m. Monday Pacific time to help return their operation to normal. A complete list of those pre-cancellations will be posted at" the company's website, the airline said.
All passengers who had their travel disrupted were told they could rebook without a rescheduling fee. Alaska Airlines urged passengers traveling Monday "to check the status of their flight at alaskaair.com, Alaska's mobile website, or by using Alaska's mobile apps for the iPhone and Android. Customers can also call 1-800-ALASKAAIR (1-800-252-7522) before leaving for the airport."
At Sea-Tac airport early Monday afternoon, hundreds of passengers were standing in lines that spilled outside the building.
The problem's cause was a combination of two fiber optic cuts in the Sprint system that connects the airline's resevations and ticketing system to the SABRE system used by many airlines and travel agencies to track and issue tickets.
Sprint spokeswoman Crystal Davis in Reston, Va., said one problem occurred at a construction site along railroad tracks between Chicago and Milwaukee, and the other was somewhere between Portland and Seattle. Alaska Airlines said a "Sprint fiber network cable severed in the Seattle area."
If there had been only one disruption, the computer system would've been able to reroute the traffic. She said the failure Monday was caused by the combination of the two cuts. It also affected some other Sprint customers in parts of Washington, Oregon and California.
At Sea-Tac International Airport, passengers reported they were being issued hand-written boarding passes.
Earlier, Alaska Airlines took to Twitter, saying, "Our data connection partner, Sprint, is experiencing a network outage which is affecting our ability to check-in customers." A message posted at alaskaair.com said, "The SABRE system went down at 7:40 a.m. and appears to be a data connection issue with Sprint."
Other airlines at Sea-Tac were not affected, according to a Port of Seattle spokesman.
One person trying to travel from Seatac Airport Tweeted, "Alaska Air's computers are down at SEA. No one can get on planes. Looks like we'll be late... "
A passenger trying to fly out of Portland Tweeted: "#alaskaair down in #pdx too, longest line I've seen in awhile. :(. Everyone just standing, waiting."
Around 9 a.m., a passenger at Sea-Tac tweeted, "Flight numbers being posted on white sheets of paper and hand written boarding passes."
The Seattle-based Alaska Airlines is the seventh-largest U.S. airline based on passenger traffic and is the dominant U.S. West Coast air carrier. It has an average of 436 flights a day at 64 destinations, including airports in Mexico and Canada.
Alaska Airlines and Horizon Air are owned by the Alaska Air Group.
Additional reporting by KING 5's Glenn Farley and the Associated Press.