West good fit for Sydney airport: Truss

Western Sydney's growing need for its own airport is a priority consideration for the federal government as it decides on a site for the harbour city's second facility.

With a population forecast to double to some four million people in coming years, western Sydney demands its own airport, Infrastructure Minister Warren Truss told a tourism and transport forum in Canberra on Wednesday.

"Surely a community with four million people needs an airport, to service their local needs if not just the wider needs of the city," the minister told reporters after the forum.

The coalition is looking at economic and social factors as it plans to stick to its commitment for a first-term announcement of where the airport will be located.

Badgerys Creek, southwest of central Sydney, is a frontrunning greenfields site where land has been set aside for decades for an airport.

Consultation was ongoing as the government tried to find a site that "has as much community support as possible", Mr Truss said.

The minister concedes that with or without an airport, western Sydney will need substantial infrastructure improvements including roads, rail and and social facilities.

"We understand the need to provide certainty to the public and to allow the aviation, transport and tourism industries to plan for the future," Mr Truss said.

"We are therefore inclined to make this decision sooner rather than later."