Redistribution of ground subtracks for aircraft noise calculations

Abstract For aircraft noise calculations, lateral flight dispersion is commonly represented by means of subtracks – a backbone track and side-tracks to each side of the backbone track – where each subtrack is assigned a movement percentage. Aircraft noise calculations impose quality demands on these subtracks, while the latter are often created based on limited information. This paper presents a method to increase flexibility when designing subtracks. The method allows to redistribute subtracks geometrically, allowing for the design of simplified track representations, for instance through a lower number of subtracks and very basic indications of movement allocations. The method is based on the geometric matching of the initial subtracks and on the estimation of the lateral movement distributions for both input and final output subtracks. No restrictions on the number of sub-tracks or on the shape of the distributions are needed, neither for the input nor for the output. A number of examples of the redistribution and its effect on aircraft noise calculations are discussed.