Vocal and public campaigning from Australia's two largest airline groups has failed to sway Australia's Productivity Commission from changing its position on the need for arbitration to resolve disputes between airport users and operators.

A coalition of airport users has backed calls from lobby group Airlines for Australia and New Zealand for reforms to the way airports are regulated.

The International Air Transport Association (IATA) says the Productivity Commission's (PC) draft report into the economic regulation of the nation's airports reached its conclusions without a balanced assessment of the evidence.

Airlines for Australia and New Zealand has expressed a "profound sense of disappointment" with the Productivity Commission's airports inquiry.