Qantas passengers were issued with handwritten boarding passes at airports across the world this morning after the company's check-in system malfunctioned.
A Qantas spokeswoman confirmed the meltdown occurred at 6.40am and had impacted on the airline's ability to print boarding passes.
Qantas has now confirmed through Twitter the problem occurred with the global reservation systems Amadeus.
In a reply post, @QantasAirways said "Hi, all ports serviced by the Amadeus system have experienced problems today, it has affected airlines globally."
Amadeus had reportedly been responsible for Qantas system outages in 2009 and 2010.
What they are saying is there has been a complete meltdown and no-one can check in.
Earlier, a company spokeswoman said all airports servicing Qantas flights were affected.
"We have had issues printing boarding passes at our domestic airports. Customers can check in online or on their smartphones, but we expect the system to be up any moment," she said at 7.45am.
The spokeswoman said people flying from Los Angeles and Auckland were checking in at the time the system went down.
"What happens in these cases is customers are given pre-printed cards, and staff fill their details in," she said.
An announcement was broadcast at Sydney Airport at 8.50am that the problems appeared to have been fixed and printed boarding passes were now being issued.
The Qantas spokeswoman confirmed all systems in airports across the world would be up and running by 9am AEDT.
The printing problems were causing only minor delays to departure times, although Melbourne was also affected by poor weather conditions, the spokeswoman added.
A Tullamarine Airport spokeswoman confirmed storms compounded problems for travellers in Melbourne, with lightning closing the airport for brief periods just before 7am and again about 7.35am.
The editor of smh.com.au, Darren Goodsir, was due to fly from Sydney to Melbourne this morning. He said many passengers were being put on to later flights because of the system failure.
"What they are saying is there has been a complete meltdown and no one can check in," he said.
"Everyone is being manually checked in and they are getting handwritten boarding passes."
In Melbourne, two check-in staff were trying to issue handwritten boarding passes for hundreds of passengers, a traveller bound for Canberra told this website.
He said passengers faced long queues and waits of up to 40 minutes to check in, and his 7.20am flight to Canberra had been rescheduled to depart at 8.30am "at the earliest".
The passenger, who declined to be named, said staff were telling passengers there was a nationwide problem with the computerised check-in system.
Another smh.com.au reader said her travel plans had been thrown into disarray by the meltdown.
"Got to airport 615 plenty of time for 730 flight to Melbourne. Printed tickets down. Waited in until 745 to be issued with hand written ticket. Got on plane. Read. Plane half full. 815: message to say storm in Melbourne. Plane mechanically unfit to fly. Got off plane. 830: Announcement to say next available flight at 230. Missed meeting. In taxi back home. A great day at the office."
An aviation security expert said a handwritten pass was still considered a legal document as long as the passenger's name and flight details were written on a blank Qantas boarding pass.
The main difference was it would not have a barcode on it.
"The threat level remains the same," the expert, who asked not to be named, said.
"But the problem in Australia is there is no requirement for photo [identification] at the gate ... for domestic flights.
"Boarding passes are swapped regularly. It is something that is very well known."
- with Glenda Kwek
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