Thousands of travellers were delayed at airports nationwide on Saturday after the Navitaire check-in system used by Jetstar, Virgin Australia, Tiger Airways and Rex failed on Saturday morning.
The three-hour outage meant airlines had to check passengers in manually, causing flight cancellations and delays of up to several hours.
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Online bookings were also affected until the system was fixed just before midday (AEDT).
Jetstar spokesman Stephen Moynihan said the system outage was caused by a power failure at a data centre in Sydney.
The airline had called in additional staff at airports to help clear the backlog of passengers, he said.
"There are knock-on delays of between one to three hours as we move passengers onto their flights," he said.
Waiting Jetstar and Virgin passengers were given food and drink vouchers to use at the terminals.
"Flight Delay Update: VirginAustralia are now handing out $8 food vouchers to cope with disgruntled passengers. It's actually working!" tweeted Sydney DJ Timmy Trumpet.
Tiger spokeswoman Vanessa Regan said the outage caused half-hour delays for several flights.
"We did have a couple of minimal delays but we expect to smooth those over now," Ms Regan said.
"The airline is doing all it can to minimise any further disruptions caused as a knock on effect of this morning's outage."
Virgin spokeswoman Melissa Thomson said three flights departing Sydney airport had to be cancelled due to congestion at the gates as a result of the outage.
While the airline was endeavouring to get all guests away, passengers were still experiencing delays of between 30 minutes to two hours, she said.
A Navitaire system crash in 2010 caused chaos for Virgin Blue passengers nationwide, with two days of flight cancellations and delays, forcing some to put themselves up in hotels.
Virgin boss Richard Branson apologised, saying it had been a "terrible 24 hours".
The airline blamed Navitaire for the chaos and said it was considering legal action, but reached a confidential settlement in 2011.
Ms Thomson said Virgin was migrating to a new IT system next year and would no longer be using Navitaire.
