"While we negotiate successfully with other suppliers to reduce costs and ultimately deliver better airfares ... charges by Australian monopoly airports are largely non-negotiable," Mr Parker said.

Australia’s five largest airports - Sydney, Melbourne, Brisbane, Adelaide and Perth - made average aeronautical revenue per passenger of $14.34 in 2016, which was $4.71 higher than the five largest airports in the US, the submission says, while operating on far higher earnings margins.

Airports worldwide had an average earnings margin of 55 per cent in 2015, according to the International Air Travel Association, while Sydney Airport enjoyed an earnings margin of 83 per cent, Melbourne 75 per cent, Brisbane 74 per cent and Perth 66 per cent.

Cutting airport fees by $4 per passenger would save airlines $648 million a year, according to Qantas, which made an after-tax profit of $980 million last year.

The airports have argued they have made significant investments over the past 15 years to allow for an influx of international competitors, which has injected new competition to the market and driven down the cost of overseas travel for Australians.

The Australian Airport Association has also told the inquiry that Qantas and Virgin have significant bargaining power with the airports thanks to the domestic market's duopoly.

The only discernible pattern is a quest for excessive returns by Australian monopoly airports.

Qantas' submission

Total passenger numbers passing though Australian airports more than doubled between 2002 and 2017, from 76 million to 159 million.

Qantas said with this massive increase in volume, charges to use airports' assets should have fallen, but this had not happened.

“Charges levied by airports bear little relation to passenger volumes, geography, type of traffic or level and quality of services and facilities," its submission says. "The only discernible pattern is a quest for excessive returns by Australian monopoly airports.”

Qantas also criticised the methodology the Australian Competition and Consumer Commission uses to monitor the profits and charges of the country's four largest airports, which only takes into account earnings from aeronautical operations.

A better measure would be to also consider the money airports made from leasing retail space and from car parking, as was done by UK regulators, Qantas said.

Qantas and other airlines are arguing for an arbitration model to be introduced that could rule on disputes with airports over fees.