According to consumer watchdog the ACCC (Australian Competition and Consumer Commission), which monitors charges at the four biggest airports, Sydney’s Kingsford Smith had the highest profit margin for its aeronautical services at 46.7% last financial year, down 3.4 percentage points.
But its profit margins on parking increased 1.5 percentage points to 73.1%. At the international terminal
“The returns that the airports get on car parking show that they do not face significant competitive constraints when setting prices,” says ACCC chairman Rod Sims.
Melbourne Airport was slightly ahead of Sydney in terms of total revenue from parking at $135.3 million compared to $133.8 million.
But on returns per car parking space, Sydney pulled in $6138, while Melbourne was about half that at $3084.
Here are the numbers compared each capital city airport:

Source: ACCC
Sydney Airport collects the highest revenue per passenger at $17.27, growing 3.9% last year. Overall, Aeronautical operations produced a profit of $331.5 million on revenues of $709.8 million.
According to ACC Chairman Rod Sims, the ACCC would like to be given some specific regulatory powers over airports to limit price increases, but so far it has been denied.
"They're completely unregulated. Various governments over time have set them up that way. We've suggested a bit of regulation over time but governments have said they'd rather they stay unregulated," Mr Sims observed.
"The airlines certainly would support us having some role here, whether it's a negotiate/arbitrate role on, whether it's some regulatory role on car parking fees.
Mr Sims said it would be a "great" outcome if the Federal Government built Badgery's Creek, and potentially sold it off to another private owner later.
"Not only would you get the benefits of competition between Badgery's Creek and Sydney Airport, but if you have a common owner of the two airports, that common owner will have an incentive to restrict investment at Badgery's Creek and delay Badgery's Creek so that it can maximise its profits at Sydney Airport."