"You couldn't book, you couldn't change any bookings, you couldn't check in somebody at the airport -- you couldn't do anything that an airline would normally use a computer system to do. We were completely without IT support for 23 hours," said Jamie Perry, GM of distribution and commercial systems at Jetstar.

Early last week Jetstar informed its customers that it was closing its Web site and call centre on Friday at 5.00 pm AEDT, with the view to reopening at 4am AEDT on Monday. The company determined that was the necessary time required to cut over from its Navitaire Open Skies reservation and distribution system, which the carrier launched with in 2004, to Navitaire's New Skies 3.0.

Perry admitted the migration was a mammoth undertaking.

"Once you make the decision to shut the system off. You are in the lap of the gods somewhat until it comes back up again," he said.

"Obviously if anything had happened during that time if there had been even worse weather than we had experienced [extreme heat in South Eastern Australia] and we had to start diverting aircraft all over the place, or if we had a problem with one of our aircraft and it hadn't been able to take off on time, we would have been completely without systems to try to manage that experience. We are so complicated in the way we operate -- all airlines are - that would have been very challenging."