Hundreds of domestic flights in Japan were cancelled or delayed on Sunday as a result of a glitch that hit data flowing between All Nippon Airways Company Limited's main reservations host computer and intermediate computers that handled downstream connections to terminals in airports. The airline has the largest share of Japan's domestic air market. The information was slowed by the glitch leading to a backlog of data that eventually clogged the system and resulted in 130 cancellations and delays of more than an hour for 306 flights. Around 69,300 passengers were affected, said ANA spokesman Rob Henderson.
The problems began to resolve themselves on Sunday afternoon and by Monday morning the airline was operating close to a normal schedule. Henderson noted ANA doesn't yet know the cause of the problem. However, in the last two weeks, three of the six intermediate computers that sit between the host and airport check-in terminals were replaced as part of the gradual phase-in of a new computer system from Unisys Limited. After the replacement a problem was suspected and the airline switched back to the old computers, but then realized it was a communications issue and not one of hardware.
News source: PC World