Sydney International Airport is earning the highest profits from car parking fees, a new ACCC report has found. Picture: Bob Barker

A new report from the Australian Competition and Consumer Commission has found a lack of competitive constraints means our four major airports — in Sydney, Melbourne, Brisbane and Perth — continue to enjoy another year of high profits on car parking.

The ACCC’s Airport Monitoring Report for 2015-16 said Sydney Airport’s car parking profit margin went up to 73.1 per cent — the highest of Australia’s airports.

Sydney pocketed a whopping $133.8 million in revenue from car parking last year, according to the report. Its car parking profit increased by 5.4 per cent in real terms to $97.8 million.

The profit margins across the other airports also remained high in 2015-16: Brisbane enjoyed a profit margin of 66.1 per cent; Melbourne Airport, 59 per cent; and Perth, 55.6 per cent.

But the consumer watchdog found more consumers were taking advantage of discounts when booking online for car parking, especially long-term parking.

Parking fees are keeping our major airports rich.Source:News Limited

“Booking online can deliver the best value car parking deals,” ACCC chairman Rod Sims said.

“In comparison, those who do not pre-book must pay drive-up prices which can be double that of online prices.”

Elsewhere, the four airports have continued to rake in profits through aeronautical revenue — the fees they charge airlines.

Sydney recorded a profit of almost 47 cents in the dollar from aeronautic revenue, or about $17.27 per passenger.

The profits from aeronautical revenue by the four airports were “substantially higher” per passenger than they were a decade ago, the consumer watchdog said.

“The ACCC estimates that over the past decade, these airports have collected $1.57 billion more in revenue from airlines than they would otherwise have collected if average prices were held constant in real terms,” Mr Sims said.

“Despite these much higher revenues per passenger, ratings of service quality are not materially different from those seen a decade ago.”

The annual report also warned the Federal Government about giving Sydney Airport first rights to build and operate the proposed Western Sydney Airport.

Mr Sims said allowing Sydney Airport to hold a monopoly would prevent competition that could benefit consumers.

“A second international airport competing with Sydney Airport will yield significant benefits to consumers and airlines,” he said.

“On the other hand, a common owner of the two airports would have an incentive to restrict investment and delay the new airport in order to maximise returns from its existing assets.”