Protecting Wilderness and National Parks

World Heritage Area noise assessment for the proposed Western Sydney Airport misleading and unhelpful

The Colong Foundation believes that overflights from the proposed Western Sydney Airport will cause significant noise impacts to wilderness in the Blue Mountains.  The Foundation fears that if the airport is approved the Blue Mountains will lose its green cachet and affect its tourist-based economy.

The draft EIS for the Western Sydney Airport must be revised to provide an adequate assessment of options that prevent aircraft noise being heard in the World Heritage Area.  In 2011 the US Parks Service prepared an EIS that established special flight rules in the vicinity of Grand Canyon National Park.  These rules ensure aircraft noise is not heard in wilderness areas[i] and this approach should be applied to the proposed airport”, said Keith Muir director of the Colong Foundation for Wilderness.

The draft EIS fails to adequately assess, avoid, minimise and mitigate aircraft noise impacts.  It fails to apply appropriate noise limits or examine flight plan options.  The draft EIS is an unsuitable basis for decisions that will significantly affect the World Heritage Area and the lives of hundreds of thousands of people in western Sydney.

“Noise peer reviewers for the draft EIS, Marshall Day Acoustics believe the aircraft noise to be potentially significant and widespread impact within the World Heritage Area[ii],” Mr Muir said.

“The aircraft noise assessment for the World Heritage Area is misleading.  The draft EIS assumes a “recommended” noise level for national parks that is much higher than measured background levels.  The assessment is additionally defective because it compares its unreasonably loud recommended noise level to a time-averaged aircraft noise level that is quiet when compared to measurements of noise levels when aircraft pass overhead,” Mr Muir said.

“Background noise in remote areas of Blue Mountains National Park has been measured at 23 to 27dBA[iii].  In the United States wilderness areas ambient noise levels has been measured at 27dBA to 47dBA[iv].  The draft EIS asserts 55dBA LAeq is a suitable recommended maximum noise level for wilderness areas, making reference to a 15 year old EPA industrial noise policy.  The recommended 55dBA LAeq noise level is at one or two orders of magnitude louder than background noise and will destroy wilderness amenity”, said Mr Muir.

“The draft EIS claims that aircraft flying over the World Heritage Area cause “minimal incursion of noise levels in excess of 55dBA” is buried on page 538 of Vol. 2. Measured aircraft noise levels from overflights at 5,000-6,000 feet are louder than this noise level, except for small regional jets with 50 seats that do generate 55dBA at 5,000 feet.  ‘Normal’ sized jets, such as jets with twin aisles and two engines, generate 64-67 dB L max ascending at 5,000-6,000 feet[v].  The time-averaged 55dB LAmax noise level understates the annoyance that would be caused by overflights in Blue Mountains national parks,” he said.

“Peer reviewers Marshall Day Acoustics point out that the characteristics of aircraft noise and natural sounds are very different, so even if aircraft noise were equivalent to background, it would still be annoying to those visiting the Blue Mountains national parks,” said Mr Muir.

For more info. contact: Keith Muir, (02) 9261 2400 (wk) or 0412 791 404 (mob)


[i] National Park Service, U.S. Department of the Interior, 2011 Feb., Special Flight Rules Area in the Vicinity of Grand Canyon National Park Actions to Substantially Restore Natural Quiet Draft Environmental Impact Statement, DES 10-60

[ii] Marshall Day Acoustics, 20 Nov 2015, Western Sydney Airport draft EIS, overflight noise peer review, page 19.

[iii] Dr Urszula Mizia, July 1994, Proposal for Noise Control Criteria for Aircraft Flying over National Parks and other environmentally sensitive areas. A discussion paper prepared by Dr Urszula Mizia for the FNA Noise Criteria Working Group in relation to aircraft flying over the Blue Mountains National Park.

[iv] US Dept. of Agriculture, Forest Service, July 1992, Report to Congress – Potential Impacts of Aircraft Overflights of National Forest System Wildernesses, Prepared pursuant to Section 5, Public Law 100-91, National Park Overflights Act of 1987, page 2-7.