So far, it's unknown when flights will be able to take off - stranding passengers on the first day of school holidays and causing chaos at the airport.
At around 5am, Sydney Airport confirmed there was a "system software failure" which was preventing planes from both taking off and landing.
Airservices Australia said the incident was down to a software failure and not a cyberattack. "Thanks for your patience", Sydney Airport tweeted at 7.24am.
"Our technicians are now working to rectify the situation", ASA said.
"As of this morning, the flight delays in Sydney have not had a direct effect on flights from the Rockhampton Airport", Mr Waters said.
According to News Corp, the universal system used by Air Services Australia has been disrupted.
Sydney Airport said in a message posted to its official Twitter feed that the "issue has now been resolved".
"Passengers are advised to contact their airline for details of their flight status". "We are working to rectify the issue while managing traffic safely".
"This is just them playing politics, and pretending somehow that you can get more out of Sydney Airport than is possible", he said. The airline had to cancel more than 20 flights on Monday as a result.