The passengers described the situation as a "crackle" and said no one could check in. (ABC News: Cameron Gooley)
A power outage at the T3 Domestic Terminal causes flight delays at Sydney Airport.
A spokesman for Qantas said they appreciate flight delays for up to an hour and that technicians are working to restore power to the terminal.
Energy issues are believed to be caused by a water burst tube.
The spokesman said electricity interruptions also hit the airport's PA system, affecting passenger communication.
Passengers arrived at the social media to describe the situation as "bad."
"I would not want to catch a flying flight," Tim Boyce told Twitter.
Others said no one was able to check in.
In a response, Sydney Airport told a passenger that the terminal operated independently of Qantas and was trying to find out when to fix the problem.
Passenger Carlo Giacco said he was waiting for an hour for his flight to Hamilton Island.
"We are quite upset that it has taken so long and there has been no communication about what's going on," he said.
"The IT system seems to be down and just delays our holiday experience and people are waiting on the island, just can not wait to get to the plane."
"We have always flown to Qantas and there have never been delays, so there is obviously a bug on the computer and we hope they will solve it, but the airport does not seem to be communicating."
Caroline Walshe said she was waiting two hours to get a friend from Melbourne.
"Nobody tells me what the portal is to my friend, there is nothing on the screens, it's just scary," he said.
"And not only, there is no one from the customer service, saying" apologize for a power failure. ""