The influence of modelling asymmetric lateral track dispersion on aircraft noise level predictions

In the Netherlands, noise exposure forecasting is based on the assumption that lateral track dispersion, for both take-off and landing, can be represented by a symmetrical probability distribution. Radar track observations at Amsterdam Airport Schiphol (AAS) show that the actual track dispersion is certainly not symmetrical. As a result, forecasting noise exposure calculations can give rather large differences in noise load compared with noise exposure calculations based on the actual tracks. An asymmetric lateral track dispersion model is presented, using three tracks per flight route. Two-dimensional analysis shows that the model gives a better correlation of the calculated noise levels using modelled and actual tracks.