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SAVE OUR CASTLE
Save Our Castle
A website promoting the removal of the introduced Australian Noise Exposure Forecase (ANEF) zoning constraints on properties in
Raymond Terrace
From Dom Swinkels:
There has been no question raised regarding the validity of the current ANEF 2025. There has
been some discussion of an additional Instrument Landing System pointing in the opposite direction
of the existing one at Williamtown to allow instrument assisted landings from both directions. This is unlikely to occur since the existing ILS technology is approaching its end of life. The existing ILS technology was first developed in the 1930s and although improvements have been made over time the technology is now being superseded by GPS methods. The GPS system was developed by the US military for military purposes but a limited form was made available for commercial use in the mid 1990s. The GPS satellites broadcast two types of signals, one of which is available for commercial uses and is used in the car mapping devices, in mobile phone and in some watches. The second type of signal from the satellites is reserved for military uses. It is 10 times more accurate and is encrypted so that it is not available for commercial devices. An improved version of GPS methods is known as Differential GPS or DGPS. In addition to
the satellite signals it uses data from a single fixed ground station to achieve improved accuracy. There are small (1-3m) errors associated with interpreting the satellite data due to the motion of the satellites and atmospheric conditions. The fixed ground station receives the same signals from the satellites as the aircraft and interprets them to calculate a location. This location will typically differ from the exactly known location of the ground station by 1-3m in each direction due to the errors referred to. The ground station then broadcasts corrections to the aircraft to compensate for these errors. This is known as a Ground Based Augmentation System (GBAS) and is currently being
implemented at airports around the world including Sydney, where Qantas use the system to make
more direct approaches than would otherwise be possible thus saving time, fuel and money. The main advantage of a GPS based system is that is not limited to a single direction in line with the runway but allows approaches from all directions. Qantas seems to be a leader in introducing this system.
The military system using the more precise encrypted satellite data is known as JPALS (Joint
Precision Approach & Landing System). Exact details are of course confidential but it is thought to
have an accuracy of better than 1 m. Since Williamtown is to be the training base for JSFs it will no doubt be equipped with a JPALS type of ground station for use by the RAAF training thus allowing instrument based training flights from all directions and not be limited to one or two long approaches in line with the runway. In particular, track 12CA08X, which is the runway 12 arrival track for the existing ILS, will no longer be the only instrument landing track but arrival tracks from all directions can be used and hence the noise footprint can be very different. This raises the question what the current ANEF 2025 is based on. ANEFs are produced by entering flight paths, flight frequency and timing plus noise characteristics of aircraft into a computer program to produce a noise map. The resulting map is only as good as the data entered. GIGO applies here. It appears that the ANEF 2025 is largely based on taking the same flight paths as were used for the ANEF 2012 with the same limited ILS facilities and simply changing the flight details and noise characteristics of the aircraft. A quite different ANEF 2025 would result if the instrument landing flight paths were changed to allow for the greater flexibility of JPALS controlled instrument landings and choosing a range of flight paths so as to minimise the noise impacts on existing homes. It seems highly unlikely that an aircraft, which will be fitted with an Automatic Ground Collision Avoidance System, ( Auto-GCAS), would not be fitted with the latest instrument landing technology.
This leads to the following questions to be asked of our local member and all the relevant ministers shortly after the election: 1. Will the Joint Strike Fighters and Williamtown air base be equipped with DGPS systems such as JPALS to allow omnidirectional instrument landing training? 2. If the answer is yes, will the current ANEF 2025 be cancelled and replaced as soon as possible with new versions based on a wide range of instrument landing paths chosen so as to minimise noise impacts on the population of the area for both the current runway and a South East extended runway without compromising the flexibility and scope of the training? 3. How soon can we expect such improved ANEFs to be made available?
