Sydney Airport flight path over the Blue Mountains

Aircraft that fly over the Blue Mountains from Sydney Airport depart from the westernmost of the parallel runways and turn towards the north-west. They are tracking towards a waypoint located over Katoomba. A waypoint is a set of co-ordinates in the air. This waypoint replaces a non-directional beacon which was a ground-based navigational aid that had been in this location since the 1950s.

Departure flight paths are organised so as to efficiently move aircraft onto their routes. The flight path that passes over the Blue Mountains is assigned to aircraft that are heading for destinations to the west, north and north-west such as Dubbo, Perth, Adelaide, Darwin, Broome, Singapore, Kuala Lumpur, Dubai, Abu Dhabi, Hong Kong and Shanghai, for example.

While this is not a new flight path, advances in navigation technology used by modern aircraft mean that aircraft are now able to fly flight paths more precisely and this has resulted in increased concentration of flight paths over the years, including this one.

Altitudes

The altitudes of traffic departing Sydney Airport will vary according to which runway the aircraft has departed from because this affects the number of track miles the aircraft has flown before it reaches the Blue Mountains. The more track miles flown, the more time the aircraft has had to increase altitude and the higher it will be over your area.

Altitudes will also vary according to other factors such as the weight of the aircraft and how heavily laden it is. For example, long-haul aircraft departing for Dubai will be much heavier than smaller aircraft heading to Perth or Adelaide due to fuel load and aircraft size. The maximum take-off weight (MTOW) for an A380 is 560,000kg and for a B747 it is 396,890kg. The MTOW of an A320 is 73,500kg and for an A330 it is 230,000kg. These differences in weight alone will affect an aircraft’s climb rate.

Even the atmospheric conditions at the time can play a part. When the weather is warm, the air is less dense and therefore there is less lift and the aircraft climbs more slowly. Due to these variable factors the altitudes quoted below are not limits and some aircraft may be higher and some lower that the ranges given.

Jet aircraft departing towards the north will generally be within the altitude range of 10,000 to 20,000 feet. Turbo-prop aircraft that have departed Sydney Airport may range from 7,000 to 15,000 feet.

For aircraft departing towards the south, jets will generally be from 15,000 to 25,000 feet. Turbo-prop aircraft will usually be from 10,000 to 15,000 feet.

Many Blue Mountains residents have told us they feel jet aircraft are lower now than in the past. We conducted an investigation into this question, looking at altitudes of aircraft that passed within a five kilometre radius of Blaxland in January of each year from 2012 to 2018. The investigation found variation in altitudes between different aircraft types but relatively little variation within the same aircraft type. The variation in altitudes between aircraft types can be attributed largely to the differing maximum take-off weight of each type. Heavier jets demonstrated a poorer climb performance than lighter jets.

The investigation also found a marked increase in airlines using A380-800 aircraft – from 23 flights in January 2012 to 126 flights in January 2018. As the A380 is the heaviest jet and as the study indicated that they have the lowest average altitude, the increased use of this aircraft type is likely to be a major contributing factor to the community’s perception that altitudes over Blaxland have decreased.

Prospects for change

Airservices has investigated whether it would be feasible to move the Katoomba waypoint. The investigation found that this would adversely impact on safety and would not be operationally feasible due to the constraints of military airspace restrictions and air traffic control sector boundary and route segregation requirements. It would also negatively impact on communities closer to Sydney Airport where the noise levels would be higher than those currently experienced in the Blue Mountains.

Western Sydney Airport

Should you be interested in information about the new Western Sydney Airport, the Department of Infrastructure and Regional Development has carriage of this matter and has a project team available to answer questions. The website is: http://westernsydneyairport.gov.au.

The website includes an interactive noise modelling tool. You can access the draft Airport Plan and Environmental Impact Statement.

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