Airservices is Australia's air navigation service provider - we provide air traffic control, aviation rescue and fire fighting and air navigation services.

Environmental Analysis for Melbourne

To achieve the best aircraft safety outcomes for Melbourne, while being cognisant of noise and emissions impacts, Airservices is working towards making Smart Tracking technology permanently available for all suitably equipped aircraft landing at Melbourne Airport. Smart Tracking has been successfully trialled at Melbourne since 2009.

All Smart Tracking at Melbourne is done within existing long-standing flight paths.

Methodology

As part of the evaluation of Smart Tracking at Melbourne, Airservices has analysed potential changes in aircraft noise distribution between 2010 and 2020 with and without Smart Tracking being used. The analysis assumes 85% of jets will use Smart Tracking by 2020. The information below includes forecast growth in air traffic of 24% to 2020, however aims to only show any difference in the noise impact of aircraft which could be attributed to Smart Tracking.

How is aircraft noise measured?

Noise is measured using A-weighted decibels, dB(A), which is a representation of the loudness of sounds in air as perceived by the human ear.

To measure the maximum sound level of a single noise event, LAmax is calculated. This indicates the highest noise level a person on the ground would hear from a single aircraft overflight (arrival or departure).

To measure average sound level over a particular time period, equivalent continuous sound level, LAeq is calculated. For example, an LAeq24 of 40dB(A) indicates that the sound energy produced by aircraft overflight which occurs periodically is equivalent to a constant sound of 40dB(A) over 24 hours.

Some useful rules of thumb:

  • A change in LAmax of at least 3dB(A) is generally required before a difference in sound level may be noticed
  • An increase in LAmax of 10dB(A) is required before most people perceive the sound to be twice as loud
  • A change in LAeq of 3dB(A) could be caused by doubling the number of overflights or by all of the aircraft being 3dB(A) louder
  • A sound outdoors will generally be 10-15dB(A) quieter indoors due to the attenuation by the building

Overview

Acceptable navigation tolerance for aircraft conducting a Smart Tracking approach creates a flight path corridor that approximately 1.1 km wide. Conventional navigation technology generally creates a corridor that is approximately 2.6 km wide. The majority of the proposed tracks have been designed within these existing 2.6 km wide corridors and in many cases follow the centre of the existing corridor. Analysis has shown that around 95% of all flights to and from Melbourne today already operate at a level of navigation accuracy which contains them within a narrow corridor. Consequently, communities underneath the centre of existing corridors will experience almost no change in noise from individual over flights as a result of aircraft making an RNP approach, while most of those on the fringes of corridors will receive slightly less noise over time.

Approaches to Runway 09

There are three Smart Tracking routes proposed to be made permanent for approaches over land to the western runway, Runway 09.

Track 1: Arrivals from the south to the western runway (Runway 09). There is unlikely to be any change in aircraft noise that is noticeable by the community.

Track 2: Arrivals from the west to the western runway (Runway 09). The level of noise of any individual flight is not expected to change for most communities under this route, however a few locations may experience decreases in LAmax by up to 6dB(A).

Track 3: Arrivals from the north to the western runway (Runway 09). This approach is slightly closer to Sunbury than the existing flight path but any changes in noise are unlikely to be noticeable and no change in the average noise level will result.

Approaches to Runway 16

There is one Smart Tracking route proposed to be made permanent for approaches over land to the northern runway, Runway 16.

Track 4: Arrivals from the north to the northern runway (Runway 16). There is unlikely to be any change in aircraft noise that is noticeable by the community.

Approaches to Runway 27

There are two Smart Tracking routes proposed to be made permanent for approaches over land to the eastern runway, Runway 27.

Track 5: Arrivals from the north to the eastern runway (Runway 27). The level of noise of any individual flight is not expected to change for most communities under this route, however a few locations may experience decreases in LAmax by up to 4dB(A) or increases by up to 4dB(A).

Track 6: Arrivals from the east to the eastern runway (Runway 27). There are no noticeable changes in aircraft noise expected.

Approaches to Runway 34

There are three Smart Tracking routes proposed to be made permanent for approaches over land to the southern runway, Runway 34.

Track 7: Arrivals from the east to the southern runway (Runway 34). The level of noise of any individual flight is not expected to change for most communities under this route, however a few locations may experience decreases in LAmax by up to 9dB(A) or increases by up to 7dB(A).

Track 8: Arrivals from the south to the southern runway (Runway 34). There is an anticipated increase in the number of persons exposed to the 60dB(A) LAmax contour for some aircraft types.

Track 9: Arrivals from the north and west to the southern runway (Runway 34). There is an anticipated minor increase in the number of persons exposed to noise of over 60dB(A) LAmax for some aircraft types, however as these areas are already regularly exposed to 60 and 70dB(A) noise events it is difficult to determine whether the permanent implementation of Smart Tracking will become noticeable.