Aircraft Noise

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Overview

The Australian aviation industry is continually striving to minimise the effects of aircraft noise on communities and many advances have been made in recent years. These have included the revision of flight path arrangements, introduction of curfews, phasing out of older, noisier aircraft, and the development of strict planning controls by many councils.

Flight Paths & Flight Zones

Ideally, aircraft fly by the most direct route and at the optimum altitude for reasons of economy and efficiency of flight operations. However, it is not always possible for aircraft to fly optimum routes because of noise and safety considerations and the competing demands of other airspace users.

What are Flight Paths and Flight Zones?

While flight paths are often depicted as single lines on a map, it is not possible for all aircraft following a particular flight path to fly precisely along the same line. In practice, flight paths tend to be corridors that can be a number of kilometres wide.

Whereas flight paths show where the aircraft fly most of the time, flight zones are also shown to describe in more general terms the airspace that may be used by aircraft operating to and from the airport.

The flight zones include all the flight paths and adjacent airspace which may be used by aircraft for safety and other operational reasons. At some times, aircraft will be seen and heard anywhere in the flight zone around an airport.

Aircraft operating at low altitudes creating the most noise are generally found within a radius of about 10 nautical miles (19km) from the aerodrome. For example, an aircraft preparing to land would be at an altitude of about 3000 feet (approximately 900 m) at 10 nautical miles from the runway threshold. Departing aircraft are usually higher than arriving aircraft at equal distances from the aerodrome.

Aircraft will, of course, also be seen and heard outside this 10 nautical mile radius.

What affects the Selection of Flight Paths?

Some of the factors that influence flight paths are:

runway orientation
the need to separate arriving and departing aircraft
the need to provide an appropriate safety buffer around aircraft following the same path or on intersecting paths
the need to integrate the flight paths for each airport in the region
aircraft performance limitations, e.g., rate of turn, climb and descent rates
avoidance of hills or other obstructions
minimisation of noise impact where possible
weather conditions
avoidance of restricted airspace, (usually for security or safety reasons)
efficient use of airspace.

The Effects of Weather on Aircraft Noise

Our Noise Enquiry Service receives many comments from callers who notice that aircraft noise is much worse on some days compared to others. Generally, the amount of noise emitted from a particular jet aircraft during landing, departure, or engine testing does not change from day to day. However, several factors may affect the sound level heard by callers at a given location. Noise propagation is a complex phenomenon that can be influenced by wind, temperature, cloud cover, fog, topography, or man made barriers such as homes or buildings.

Noise is essentially a sound wave distributed in equal directions away from the source. Generally, noise levels decrease as the distance increases between the source and the receiver. However, the direction in which the sound waves travel can be altered by weather conditions which may result in varying noise levels at the same location at different times.

Temperature inversions, which occur when the air temperature increases as altitude increases, causes sound waves to bend down towards the ground, which may increase the sound heard by a receiver.

Another factor, wind, generally causes sound waves to bend in the direction of its flow. For example a wind with an easterly component one day may well have a westerly component on the next day. When this occurs residents on either side of a flight path may hear changes in noise levels.

These differing weather conditions do not cover all possibilities but provide an indication of how weather may alter the propagation of sound waves. Wind and temperature conditions also have effects on the performance of aircraft which can cause changes in sound levels heard on the ground.

To lodge a complaint regarding aircraft noise, please use our online form.

To contact the Noise Enquiry Service phone 1800 802 584 (freecall) or 1300 302 240 (local call)
or write to:
Noise Enquiry Service
PO Box 211
Mascot NSW 1460
Email: community.relations@airservicesaustralia.com