Qantas domestic passengers in Australia experienced long delays after the airline's check-in system failed on Sunday.
The Amadeus system server crashed at 8.30am AEDT, causing about 80 flights nationwide to revert to manual check-ins.
The airline says international flights were also affected.
Domestic passengers were lined up outside the doors of the Qantas terminal at Sydney airport waiting to check in.
The ABC reports that a similar system failure in November caused extensive delays.
