Flights from the new western Sydney airport will avoid residential areas "as much as possible", according to a fact sheet released last week.

But if flying over houses is unavoidable, residents shouldn't get both arriving and departing planes - "where possible", the information from the department of infrastructure, transport, regional development and communications said.

The document acknowledged that "significant changes" had been made to the flight path design process after community feedback on indicative routes in 2015.

Those routes would have seen five inbound flight paths converging over Blaxland.

The new plans now include "12 design principles that require the development of flight paths to minimise the impact on the community and the environment, while maximising the benefit of the airport".

The principles stipulate that "aircraft arrivals will not converge through a single merge point over any single residential area".

The plans stipulate that safety is "non negotiable".

An expert steering group is overseeing the design process for the flight paths. It is led by the federal infrastructure department and includes representatives from industry and regulatory bodies, Airservices Australia, Civil Aviation Safety Authority and the chair of FoWSA, the Forum on Western Sydney Airport.

The fact sheet said there will be ongoing community engagement throughout construction of the new airport and design of the flight paths and airspace.

The preliminary design phase is underway and the proposed design will be open for public consultation as part of the upcoming environmental assessment process.

Blue Mountains mayor, Mark Greenhill, said the fact sheet "continues the culture of secrecy" around flight paths.

"Our community deserves to know, especially this close to the opening of the airport."

He suggested the government was delaying the release of details flight paths "until they have got construction to the point where they can tell the community it is too late".

And Susan Templeman, Macquarie MP, called it a "waste of paper".

"This is a classic example of producing something to make it look like there's progress, when in fact residents who will live under the flight path are kept in the dark about what our future will sound like.

"There is nothing it this so-called fact sheet to give any confidence to Blue Mountains residents that our concerns about aircraft noise are being acted on."

The plans state that safety is "non negotiable".

An expert steering group is overseeing the design process for the paths, led by the federal infrastructure department and including representatives from industry and regulatory bodies, Airservices Australia, Civil Aviation Safety Authority and the chair of FoWSA, the Forum on Western Sydney Airport (FoWSA).

The fact sheet said there will be ongoing community engagement throughout construction of the new airport and design of the flight paths and airspace. The proposed design will be open for public consultation as part of the upcoming environmental assessment process.

Blue Mountains mayor, Mark Greenhill, said the fact sheet "continues the culture of secrecy" around flight paths.

"Our community deserves to know, especially this close to the opening of the airport."

He suggested the government was delaying the release of flight paths details "until they have got construction to the point where they can tell the community it is too late".

Susan Templeman, Macquarie MP, called it a "waste of paper".

"This is a classic example of producing something to make it look like there's progress, when in fact residents who will live under the flight path are kept in the dark about what our future will sound like.

"There is nothing it this so-called fact sheet to give any confidence to Blue Mountains residents that our concerns about aircraft noise are being acted on."

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