Computer glitch affects United worldwide

CHICAGO, Jan. 4 (UPI) -- United Airlines' computerized reservation and check-in system went dark for about four hours and caused flight delays worldwide, a report said.

United said it was investigating the cause of the mysterious blackout in the system called Apollo for about four hours Tuesday evening.

While no flights were canceled, passengers at airports that included Chicago's O'Hare, London's Heathrow and Tokyo's Narita were delayed up to 90 minutes as airline workers manually checked boarding passes and paper vouchers.

"We were able to hold some flights and rebooked some customers," United's Jean Medina told the Chicago Tribune.

The outage affecting Apollo, which United uses worldwide, also made it impossible to book future flights on the airline.