Passengers travelling to or from Sydney Airport on Monday were met with a change to their itinerary due to an Airservices system suffering an IT issue.
Sharing update information via Twitter, Sydney Airport said the Airservices system issue had been resolved at approximately 8.40am AEST.
Airservices Australia also took to Twitter to update delayed passengers, tweeting at 9.20am AEST that the technical issue experienced at Sydney Airport had been addressed, and that the country's air navigation service provider was "now working to resume to normal operations and clear the backlog of flights".
Following the update from Airservices, the service provider told passengers to contact their airline for details of their flight status.
ZDNet understands passengers travelling to Sydney from Brisbane via Virgin Australia are now faced with a two hour-plus delay as the airport looks to clear its backlog of interrupted flights.
"Due to an issue with the Air Traffic Control system at Sydney Airport this morning, there will be an impact to flights operating to and from Sydney today," Virgin said in a statement Monday morning.
"Virgin Australia is working to have all guests on their way as quickly and safely as possible.
"We will be contacting those guests who may be impacted and we encourage all guests to check the status of their flights here: flightstatus.virginaustralia.com."
According to the ABC, the fault relates to the flight planning system which feeds into the radar picture. The report explained that without it, controllers cannot see which plane is which.
It is also believed the data connection between Sydney and Melbourne is down.
Qantas is also urging customers to check their flight status, confirming "significant delays" at Sydney Airport are affecting all airlines.