SPOKANE -- Alaska Airlines is recovering from a computer networking problem that threw its passenger check-in system offline early Monday morning.
Shortly before 1 p.m. PT, Alaska Airlines said the system was back in operation.
Flights scheduled to depart Monday afternoon are expected to leave on schedule, but the airline was dealing with passengers who were scheduled for morning departures.
At Spokane International Airport, hundreds of passengers were standing in lines because their flights were delayed or cancelled.
Some passengers experienced delays up to five hours.
The problem's cause was a combination of two fiber optic cuts in the Sprint system that connects the airline's reservations 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.
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."