Qantas has confirmed a global outage of Amadeus' Altea reservation system is the cause of chaos at check-in counters nationally for the airline on Sunday.
"Global issues with Altea system affecting check-in," Qantas said on its official Twitter page.
"Issue resolved and ports will be back online shortly. We're sorry for the inconvenience."
Affected travellers took to Twitter over the weekend with several saying flights were delayed as a result of the computer system crash.
Several reported planes on the tarmac for extended periods due to the outage.
Pictures tweeted from Tullamarine in Melbourne show long queues at the check-in counters.
An iTnews reader similarly reported chaos in Perth this morning.
The cause of the crash has not been confirmed.
However, several Twitter users speculated that it may have been caused by the addition of a "leap second" overnight "to keep the world's official atomic clocks in sync".
A Qantas spokesperson has been contacted for comment and confirmation of the cause.
The reservation system portion of Amadeus' Altea suite is used by 140 airlines worldwide.
A similar outage hit the hosted Altea system, affecting airlines globally, in January.
A spokesperson for Amadeus has also been contacted for comment.
More to come...