A 20km stretch of land surrounding the future western Sydney airport will be subjected to noise levels similar to or louder than a washing machine or vacuum cleaner more than 100 times a day by 2040, preliminary flight path analysis shows.
Proposed flight paths released on Tuesday have been designed to avoid areas either currently or projected to be densely populated in coming decades, ahead of the airport beginning operations in late 2026.
However noise assessment modelling released by the government appears to show existing suburbs which sit south of Mount Druitt could be among the areas most affected by noise from the new airport.
The federal government’s modelling appears to show these suburbs fall within a narrow stretch of land that, by 2033, will be subjected to multiple instances each day of noise pollution from aircraft movement either of or “well in excess” of 70 decibels outdoors and 60db indoors – loud enough to disturb normal conversation.
A chunk of the south of St Clair will see overhead flights cause outdoor noise levels in excess of 70db up to 19 times per day by 2033. A handful of affected houses will experience these events 20 to 49 times per day by 2040.
Luddenham Public School and surrounding residential properties are expected to experience between 10 and 19 overhead flights each day by 2033 that will cause noises loud enough to disrupt indoor conversation.
By 2040, when the airport’s operations have significantly ramped up, the area affected by daily noises above 70db will expand, though will still be largely confined to a narrow strip of land echoing the runway’s orientation.
Even by 2033, land closest to the airport will experience noise of at least 70db more than 100 times a day, with areas less affected subjected to these events between five and 20 times a day.
An increase of 10 decibels represents a doubling in perceived loudness, with 0db the threshold of human hearing, 50db similar to moderate rainfall, and 70 likened to being near a washing machine or vacuum cleaner.
Sydney’s second gateway and first 24-hour passenger airport will alleviate pressure on Sydney’s Kingsford Smith airport, which is subject to an 11pm-6am curfew and movement limits due to its close proximity to residential areas.
Western Sydney airport’s one runway is designed to guide departing and arriving planes in a manner that minimises noise impacts over the future Bradfield CBD that will be built south-east of the airport as part of the Aerotropolis.
In addition to existing airport movements and the future Aerotropolis, the airport’s flight paths are constrained by air force-restricted airspace over Glenbrook in the Blue Mountains that prevents planes departing north-east from making an immediate left turn.
During the day, flights will approach and leave the airport predominantly from its west and north, with fewer movements from the east and south, to ease the air traffic control burden that already has to navigate aircraft to airports in Mascot, Bankstown and Camden.
During overnight periods, planes will largely avoid the majority of inner and suburban Sydney, with no flight paths set south of Hornsby, north of Cronulla or east of the airport.
There are also contingency flight paths for periods of increased winds, as well as for times of extreme heat when air density decreases and some planes take longer to gain altitude.
The government has launched an online tool that allows residents to see potential noise impacts and expected daily aircraft movements relevant to their address, as it invites community consultation.
While the flight paths released on Tuesday are preliminary, Guardian Australia understands there is limited scope to tweak the proposed routes due to Sydney’s geography.
The federal transport minister, Catherine King, said the preliminary flight paths were developed according to principles that included “minimising flights over residential areas and reducing the impact on the community of aircraft operations at night”.
“The Albanese government is committed to balancing the needs of the community, environment, industry and users of the broader Greater Sydney airspace, while maintaining safety as a priority, in the design of WSI’s (Western Sydney International) flight paths,” King said.
King said the department will hold community information and feedback sessions across western Sydney and the Blue Mountains in coming months.
The preliminary flight paths were developed by an expert steering group which included the department of infrastructure and transport, AirServices Australia – the government body responsible for air traffic control – the Civil Aviation Safety Authority, the defence department and the airport’s operator, WSA Co.
The government will release a draft environmental impact statement later this year that will examine noise, social and environmental impacts of the proposed flight paths. This will guide noise insulation and property acquisition policies for the surrounding area.
