Explanation of the Noise-Footprint animation
The film shows a simulated arrival of a B737 in flight direction 07 on the south runway of the parallel runway system in Frankfurt. On the left a CDA is simulated, on the right the conventional arrival at 4000 ft above sea level is shown (corresponds to around 1120 m above the ground). The altitude data shown in the film all refer to height above sea level. Frankfurt Airport is about 100 m above sea level.
Please note that the film shown is only a simulation to demonstrate the effect of the CDA measure. The noise-abatement effects occur here at a distance away from the airport. Please see the first measurement station in the film. As of the 2nd measurement station, the arrival can be compared with a conventional arrival..
Information on noise calculation
In principle, the calculation result of an air traffic noise forecast is always less accurate the greater the distance to the airport and the lower the noise incidence resulting from the air traffic.
This is due on the one hand to physical effects and, on the other hand, to effects of the calculation procedure. The individual aspects are briefly outlined in the following
1. Physical influence factors
1.1 Meteorological influences
The greater the distance between the aircraft and the respectively observed incidence location, the greater the meteorological influence. At the latest at distances as of around 500 m, and depending on the weather situation, very different noise incidences can occur.
1.2 Description of air traffic
The greater the distance to the airport, the greater the individual deviations of an aircraft from the usual position may be. This applies for the lateral dispersion and for the altitude of the aircraft above ground level. The resulting effects can only be inadequately represented with the usual approaches for the description of a dispersion. In the case of departures, this affects the whole flight path. In the case of arrivals, it particularly affects the merging zone until reaching the final descent to the airport.
2. Calculation model
For air traffic noise calculation, Germany currently uses the AzB (instructions for the calculation of noise protection zones) dated 19.11.2008. This calculation routine was developed to fill out the law on the protection against air traffic noise.
Like any calculation model, the AzB represents an abstraction and simplification of the reality. This simplification and abstraction are necessary due to the fact that nature has so many different manifestations that a generalisation and categorisation is unavoidable for practical purposes alone. Although the AzB by no means takes account of all effects, an air traffic noise calculation for the Frankfurt region in accordance with the law for the protection against air traffic noise takes more than 24 hours even on modern computers.
As the AzB was developed as a calculation routine to the air traffic noise law, in view of the restrictions outlined above, this calculation routine takes account mainly of those effects which are important for the purpose of the law. This is the most accurate calculation possible of the air traffic noise incidence in the protection zones specified by the law, i.e. the highly burdened areas.
The lowest noise levels which, according to the law for the protection against air traffic noise, must be determined amount to (outside at the window) LAeq,Day = 55 dB(A), LAeq,Night = 50 dB(A) and LAmax,Night = 6 x 68 dB(A). For areas with these or higher air traffic noise incidences we can assume a high level of accuracy of the air traffic noise determination.
For areas with lower noise incidences we can assume an increasing inaccuracy of the calculation results. A precise quantification of the inaccuracy is currently not possible as in this level range no systematic studies on accuracy have been carried out.
Insofar as the air traffic in these areas can, however, be described with adequate accuracy, we can assume that the calculated values for incidence locations which lie directly below the flight routes are a relatively good reflection of reality. For incidence locations to the side of a flight route, however, we can expect a tendency towards overestimation of the air traffic noise incidence as the AzB always assumes relatively favourable conditions for noise dissemination. Noise reductions such as occur in the case of a cross wind or head wind situation are not taken into account in the AzB.
But even within the protection zones subject to the air traffic noise law, deviations are possible between a calculation in accordance with the AzB and measurement results, not least due to the effects cited under point 1 above. However, according to the Federal Administrative Court (BVerG 11 A 9.97), such a deviation is insignificant relative to the purpose of the calculation routine. According to the court: "The scope for action of the legislator thus also extends to the establishment of the method for the calculation of the noise incidence burden which is to be compared with the incidence limit values. In this area in particular, simplification and generalisation are unavoidable."
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This website is exclusively for demonstration purposes. We do not accept any liability for the data contained therein, their correctness, accuracy or any resulting conclusions about actual flight movements in the airspace shown.
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