Aug. 6, 2013 at 6:05 AM ET
Dozens of flights were canceled or delayed worldwide early Tuesday after a major computer software outage forced several airlines to manually check-in and board passengers - with some staff using pen and paper.
Carriers using the Texas-based Sabre reservations system - including American Airlines, Alaska Airlines, JetBlue, Virgin and Etihad - lost connection for about four hours, starting at about 9:30 p.m. ET Monday.
The system was restored at about 2.30 a.m. ET Tuesday, but not before dozens of flights were delayed because airport-based airline staff had to process passengers manually.
At least three airlines – Alaska, Virgin Australia and Abu Dhabi-based Etihad – were forced to issue boarding passes using pen and paper.
Long lines quickly grew at U.S. airports, including San Francisco where passengers posted pictures to Twitter.
At London Heathrow, there were minor delays to two Virgin Atlantic departures to the United States.
Virgin Australia, which had to cancel at least 12 domestic departures from Sydney, at least eight from Melbourne and at least four from Perth, urged passengers to consider staying at home and traveling another day.
“Not much fun for us trying to get back to our families,” said Melbourne-based Twitter user Janet M.
“These things happen,” said Twitter user Paul, who posted a picture of his “state of the art” handwritten Virgin Australia boarding pass.
Etihad asked passengers to arrive earlier than usual at airports.
Alaska Airlines spokeswoman Bobbie Egan told the Associated Press that about 50 of its flights departing Seattle Monday night were delayed by up to an hour due to the outage.
Nancy Castles, a spokeswoman at Los Angeles International Airport, said 17 flights there experienced delays of up to 45 minutes.
Jet Blue spokeswoman Tamara Young said it had suffered “some delays due to the outages of unknown length.”
“It's our understanding that other airlines and travel agencies are also impacted by this,” American Airlines spokesman Matt Miller added.
Flights in the air were not affected.
Dallas-Forth Worth-based Sabre, which provides IT support to dozens of global airlines, apologized for the disruption.
“Sabre customers were unable to connect to our system for a period of time this evening,” spokeswoman Nancy St. Pierre said in a statement. “This has been restored and everyone is now able to connect to Sabre. We apologize and regret the inconvenience caused.”
She said the system had been restored at about 2:30 a.m. ET.
Most airlines use lightly-customized versions of similar software provided by Sabre or its main global rival, Amadeus.
NBC News’ Olivia Santini and Christopher Nelson contributed to this report.