Noise map for Western Sydney Airport “potentially misleading”

Finn Connolly | 13/07/2023 |5 min read

Until further information is released, the new “Western Sydney International airport aircraft overflight noise tool” may be misleading.

Since the announcement of the Western Sydney airport in 2014, residents have been calling for the flight paths and predicted noise levels to be released to the public. In June 2023 the Western Sydney flight path tool was released, allowing residents to see the proposed flight paths and the predicted noise levels. However, Dr Eric Ancich explains that until the flight tool publicly discloses how the noise levels were predicted, the data presented to residents may be unreliable.

Dr Ancich, a chartered engineer explains that the tool generally used in Australia to measure noise from aircraft, the Integrated Noise Model (INM), only measures the noise made by aircraft at an average. If the flight path tool bases its information on average data, flights could be far louder than predicted. Dr Ancich refers to an independent report he authored, from 2019. The report measured the noise levels of aircraft from Sydney Kingsford Smith Airport passing over areas that would be potentially effected by the Western Sydney airport. The results of the report were compared to the predictions done by the Environmental Impact Statement.

“We were assisted by Blacktown city council, they provided instrumentation. They wanted to know what it would be (the noise) over Blacktown. At that stage aircraft would be flying over council chambers. At the time the EIS indicated in 4 years there would be 5-70 events over Blacktown at 70 decibels. Using the Maximum instantaneous data rather than average, indicated it would actually be 70 decibels or higher 50 times a day”.

“A difference of 10 decibels is a four-fold difference in sound. So the real noise levels could be 4 times as loud as the EIS were suggesting. That’s because the EIS was based off average data were as ours was measured directly off the aircraft”

Dr Ancich states that INM is a reliable tool when used for its intended purpose, measuring averages. However, if used to provide data for the flight path tool it is unable to consider flights that are noisier due to “single events”. These single events could be weather conditions, wind conditions or anything that could cause an aircraft to fly lower and therefore make more noise.

“Until we know how the noise tool gathers data it is potentially misleading. The real number could be 20 decibels higher. That it is why it is so important that the data is not predicted on average data but rather maximum instantaneous data”.

Decibel chart ( Image Credit: Hearing Health Foundation)

While it is impossible to say what the flight path tool has used to predict noise levels, there is reason for concern that it could be INM.

In the case of the Brisbane International Airport’s parallel runway, noise levels over residential areas were predicted and made available to residents. However the data was gathered using INM according to the the Brisbane Flight Path Community Alliance which caused a major disparity in predicted and actual noise levels.

When flights began on the new routes in 2020 residents were angered as they were far louder than predicted.

The left image was retrieved from the Brisbane National airport flight path tool. The predicted noise levels are shown to have a large disparity between the noise levels measured by residents on the right.

(Image Credit: BNE flight path tool, ExPlane data points, Brisbane Flight Path Community Alliance)

Similarly to Western Sydney the Brisbane airport also utilised a flight path/noise tool, allowing residents to view flight paths and noise predictions, however due to lack of transparency it’s accuracy suffered. it was found in a 2021 report by the Aircraft Noise Ombudsman that at the time the flight path tool was released, flight paths were not yet finalised. As the flight paths changed the projections on the website were altered without leaving a log of any adjustments.

Currently the Brisbane flight path and noise tool (as seen above) does not even account for noise modelling after the new runway.

Given the governments history of inaccurate noise predictions and a lack of clarity from past flight tool’s, Dr Ancich recommends transparency from the Australian government in regards to the Western Sydney overflight noise tool.

“The average person doesn’t want to know the average noise but rather what will be going over their house”.

“Until the EIS comes out later this year there is no way of knowing what is presented is factual. It needs to be released and be subject to peer review.”

“I am not a critic of the airport. I do not have skin in the game. What I am opposed to, is not telling the community what the true situation is.”

 The Western Sydney International airport aircraft overflight noise tool’s method of calculating noise levels will likely be released in the EIS later this year.

Western Sydney Airport is expected to open in 2026.