DALLAS, Aug. 6 (UPI) -- Carriers using the Texas-based airline reservation system Sabre reported delays and cancellations early Tuesday because software failed, airport officials said.
Dozens of flights were affected worldwide after the outage forced airlines that use the system to manually check-in and board passengers, NBC News reported.
The system lost connection for about four hours beginning late Monday and wasn't restored until early Tuesday.
As a result, dozens of flights were delayed because staffers at airports 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.
"Sabre is experiencing a system issue," the company said in a tweet shortly after the trouble began. "Our technology team is working as quickly as possible to resolve the situation," CNN reported.
The Sabre system is used by more than 300 airlines and more than 100 airports worldwide.