Melbourne Airport has returned to normal after a power blackout caused chaos this morning.
Airport spokeswoman Anna Gillett said services had all but returned to normal late this afternoon as airlines worked through the backlog of delayed flights.
"The backlog has pretty much cleared ... we're looking pretty good. We’re pretty much operating to schedule at the moment," she said.
Ms Gillett said 10 international flights had been delayed because of the blackout, but was not sure how many domestic flights had been affected.
The blackout temporarily grounded flights and threw schedules into disarray, sparking passenger confusion.
The power went out abut 9.20am and was back by 10.40am - but there was a backlog of passengers trying to check in and get through security.
The power cut meant the airport's lights went out, security gates were closed and shops were unable to serve customers.
'A bit post-apocalyptic'
Virgin passenger Laura Hamilton said the security gates were closed for about 30 minutes, before security staff began searching bags manually.
She said there was an audible groan from people around her when the lights went down, which stayed off for about an hour.
''It's pretty frustrating. People are just sitting around and looking p----- off. Everyone has basically given up on their day,'' said Ms Hamilton, a Fairfax employee.
Ms Hamilton said she and her partner, Stu, were scheduled to fly to Brisbane at 10am but had been told their flight would not leave until 3pm.
Earlier, a Virgin spokeswoman said normal services had resumed, but said passengers scheduled on flights for the rest of the day could expect ''some minor delays'' as the airline worked through a backlog.
Liam McCallum, of Adelaide, said the power was out for at least an hour. His flight to Adelaide was due to depart at 9am, but he has been told it will now leave at 8pm tonight - 11 hours late.
"All the lights went off and after venturing around I think they powered it down more, until there was just nothing on at all. No screens, no nothing," he said.
"I went to purchase something and the shop had no power and the traffic lights were down so police were redirecting traffic.
"Everything just kind of shut down at once. It was very gloomy, it was a bit post-apocalyptic.
"There were dark figures everywhere walking around and big queues."
No flights departing
Earlier, Ms Gillett said the airport experienced a ''major power outage'' at 9.20am, which then began progressively resuming in some terminals from 9.45am.
''There is power throughout various parts of the airport. But at this stage we do not have flights departing,'' she said.
''But we're working very hard to get the issue resolved and that's the main focus, to get it resolved to get people going again.
''We appreciate this is causing some inconvenience for people and we apologise for that, but we are working as quickly as we can to get it resolved.''
Ms Gillett said the outage was not dangerous.
She said airport officials were unsure what caused the problem, and was unsure how many passengers were affected.
But some airlines claim that their flights have not been affected.
'Minor' power delays
A Jetstar spokesman said the airline had experienced minor power delays, although normal service had been restored.
''There are minor delays at check-in. Back-up power has kicked in and all flights are operating normally,'' he said.
Qantas said its passengers were not affected.
''From a Qantas perspective it's not impacting our services at this stage. We've got back-up power so that's allowing us to continue our operations,'' a Qantas spokeswoman said.
It is believed the power outage is affecting Customs operations and is believed to have sent three of the four terminals at the site into darkness.
Australian Customs confirmed passengers were being delayed while going through to the boarding gates.
A Customs spokeswoman said there were delays processing passengers both arriving on flights and scheduled to leave, as processing had to be done manually.
Melbourne Airport tweeted about 10.20am that power was gradually being restored, but that there would be delays "as services recover".
Forty minutes later, the airport tweeted: "We are working through delayed flights as quickly as we can. Thanks for your patience."
Melbourne Airport's website and its mobile phone app appears to have crashed this morning while people were seeking out information about what has been happening.
The outage meant the state government postponed an announcement at Tullamarine today.
Transport Minister Terry Mulder was scheduled to open a new drive-on ramp at the airport's long-term car park at 10.30am, but a spokeswoman said the event had been delayed.
Affected passengers and visitors took to Twitter to vent their frustration.
Seb Hussey reported that he was stuck in the airport carpark due to the power outage.
"I'm currently stuck in @Melair (Melbourne Airport) Carpark cos all power just went out! WHAT TO DO!!!," he tweeted.
Other Twitter users said passengers were stuck in aerobridges linking planes to the terminal due to the outage.
Jemena Electricity, which provides power to the area around Tullamarine, said it was not affected by the outage as the airport had its own electrical substation.
Not the first time
Today's blackout was not the first time the airport was hit by power problems. In May last year passengers experienced delays of up to 90 minutes, while in February Virgin passengers experienced long waits.
Ms Gillett said officials were trying to determine the cause of today's blackout, but said power outages were not unexpected.
''It's actually not that uncommon for this to happen, we are a high consumer of power as you could imagine,'' she said.
''We have a number of systems in place but at this stage I don't want to speculate on what the problem was for this one."
Tiger Airways said it experienced minimal disruption during the blackout, as all morning flights had taken off before the power went down.
A spokeswoman said the only flight delayed was the flight to Sydney scheduled for 11.50am, which was delayed less than an hour.
- with AAP