Figure 3-2: Receptors Not all recep

Figure 3-2: Receptors Not all receptors are relevant to all cases, and reference results for a given case are only provided at relevant receptors. For example, noise levels calculated at receptor R16 for cases involving straight departures (route ID: DS) would be below what would contribute to valid noise contour levels, given the distance between the receptor and the ground track. Results at this receptor for this case are therefore not considered relevant. Table 3-2 below gives the mapping of the receptors that are relevant to each of the four route IDs, namely arrivals (A) and departures (D) on curved (C) and straight (S) routes. Table 3-2: Relevant receptors for reference case routes 4 REFERENCE CASE RESULTS There are three categories of reference case results: SEL results, segmental results and grid results. These are described in the following sections. 4.1 REFERENCE SEL RESULTS The reference SEL results are sound exposure levels calculated for each of the reference cases listed in Table 3-1, at the relevant receptors given in Table 3-2. These results are presented in Appendix B Table B-1 and listed in the accompanying workbook in worksheet B-1_SEL_Results. Computing overall SEL results is a relatively quick and simple modelling task. These results therefore provide a benchmark against which noise model developers can check the performance of a new model. Making such a comparison will highlight where differences exist between the overall outputs of a development model and the reference results. Results at different locations are sensitive to different elements of the noise calculation. For instance, receptors R06-R11 are affected by aircraft in flight, so outputs may match the reference SEL results even if there are errors in the ground-roll adjustment algorithms. Receptors R02-R05, however, are near to the runway and therefore require the ground-roll adjustments to be correctly implemented for the outputs to match the reference SEL results. Comparing the SEL results at different receptors will therefore help developers identify areas where a development model deviates from the Volume 2 methodology. Once these areas are known, focused diagnosis can be undertaken using the reference segment results, as described in the next section. 4.2 REFERENCE SEGMENTAL RESULTS The reference segmental results comprise the results for the main calculation parameters for each segment of the trajectories of the twelve reference cases. These parameters cover: profile geometry; the distance and thrust for interpolating NPD curves; the baseline SEL; distances and angles for calculating the noise adjustments; the noise adjustments; and the segment SEL. The full list of parameters is presented in Appendix B Table B-2. It is recommended that noise models are implemented with a means for exporting calculation data in precisely this format. This will facilitate the comparison of a development model’s outputs with the reference results, and therefore the development of the model.