Hundreds of United Airlines passengers at Sea-Tac Airport departures were delayed this morning by a United Airlines computer failure that grounded flights around the country.
Eight of 29 scheduled United flights from Sea-Tac Thursday were affected by the computer problem or by its lingering side effects.
Passengers on those eight flights suffered through delays of up to two and a half hours.
A United flight scheduled to leave Sea-Tac at 5:56 a.m. for Chicago, didn’t depart until 8:32 a.m.
The outage lasted for about two hours this morning. At Sea-Tac the delayed flights, with one exception, were all part of the former United route structure before it merged with Continental Airlines.
Flights flown by Continental before the merger, with the exception of an afternoon flight from Sea-Tac to Newark, were unaffected by the computer issue.
The computer problem was the third large outage for United this year. United after the merger migrated its flight planning and operations work to a computer formerly used by Continental. United, however, has had problems merging its flights into that system.
The outage affected about half the flights in United’s mainline network. Flights operated by regional carriers on United’s behalf were unaffected.
Although the computer system was running correctly by mid-morning, the morning delays continued to domino through the system as planes arrived for later flights hours behind schedule.
A United flight from Sea-Tac to Denver scheduled to leave at 3:10 p.m., for instance, was rescheduled to leave at 4:20 p.m.
Another United flight from Sea-Tac to Newark set to depart at 3:24 p.m. was reset for 4:05 p.m.
United is the world’s largest airline with 5,500 flights daily.
During the system failure, some furious passengers vented their anger on social media sites, the Associated Press reported.
‘‘Does anyone have a Radio Shack computer or abacus to help United get their system fixed?,’’ tweeted Lewis Franck, a motorsports writer who was flying from Newark, N.J. to Miami Thursday to cover the last race of the NASCAR season.
In a subsequent phone call with The Associated Press, Franck added: ‘‘Why is there a total system failure on a beautiful day? What happened to the backup and the backup to backup?’’