{
  "url": "https://openlegislation.uk/eu-directive-2015-996/annex/appendix-C",
  "json_url": "https://openlegislation.uk/eu-directive-2015-996/annex/appendix-C.json",
  "legislation": "eudr/2015/996",
  "legislation_title": "Commission Directive (EU) 2015/996 of 19 May 2015 establishing common noise assessment methods according to Directive 2002/49/EC of the European Parliament and of the Council (Text with EEA relevance)",
  "legislation_url": "https://openlegislation.uk/eu-directive-2015-996",
  "path": "annex/appendix/C",
  "kind": "appendix",
  "number": "C",
  "heading": "Modelling of lateral ground track spreading",
  "text": "It is recommended that, in the absence of radar data, lateral ground track dispersion be modelled on the assumption that the spread of tracks perpendicular to the backbone track follows a Gaussian normal distribution. Experience has shown that this assumption is a reasonable one in most cases.\nAssuming a Gaussian distribution with a standard deviation S, illustrated in Figure C-1, about 98,8 percent of all movements fall within boundaries of ± 2,5·S (i.e. within a swathe of width of 5·S).\nFigure C-1\nSubdivision of a ground track into 7 subtracks\n(The width of the swathe is 5 times the standard deviation of the ground track spreading)\nA Gaussian distribution can normally be modelled adequately using 7 discrete sub-tracks evenly spaced between the ± 2,5·S boundaries of the swathe as shown in Figure C-1.\nHowever, the adequacy of the approximation depends on the relationship of the sub-track track separation to the heights of the aircraft above. There may be situations (very tight or very dispersed tracks) where a different number of subtracks is more appropriate. Too few subtracks cause ‘fingers’ to appear in the contour. Tables C-1 and C-2 show the parameters for a subdivision into between 5 and 13 subtracks. Table C-1 shows the location of the particular subtracks, Table C-2 the corresponding percentage of movements on each subtrack.\nTable C-1\nLocation of 5, 7, 9, 11 or 13 subtracks\n(The overall width of the swathe (containing 98 % of all movements) is 5 times the standard deviation)\nSubtrack number\nLocation of subtracks for subdivision into\n5 subtracks\n7 subtracks\n9 subtracks\n11 subtracks\n13 subtracks\n12/13\n± 2,31·S\n10/11\n± 2,27·S\n± 1,92·S\n8/9\n± 2,22·S\n± 1,82·S\n± 1,54·S\n6/7\n± 2,14·S\n± 1,67·S\n± 1,36·S\n± 1,15·S\n4/5\n± 2,00·S\n± 1,43·S\n± 1,11·S\n± 0,91·S\n± 0,77·S\n2/3\n± 1,00·S\n± 0,71·S\n± 0,56·S\n± 0,45·S\n± 0,38·S\n1\n0\n0\n0\n0\n0\nTable C-2\nPercentage of movements on 5, 7, 9, 11 or 13 subtracks\n(The overall width of the swathe (containing 98 % of all movements) is 5 times the standard deviation)\nSubtrack number\nPercentage of movements on subtrack for subdivision into\n5 subtracks\n7 subtracks\n9 subtracks\n11 subtracks\n13 subtracks\n12/13\n1,1 %\n10/11\n1,4 %\n2,5 %\n8/9\n2,0 %\n3,5 %\n4,7 %\n6/7\n3,1 %\n5,7 %\n7,1 %\n8,0 %\n4/5\n6,3 %\n10,6 %\n12,1 %\n12,1 %\n11,5 %\n2/3\n24,4 %\n22,2 %\n19,1 %\n16,6 %\n14,4 %\n1\n38,6 %\n28,2 %\n22,2 %\n18,6 %\n15,6 %",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eudr/2015/996/annex/appendix/C",
    "retrieved_at": "2026-11-01T15:21:38.862218+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}