# 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), Division: Treatment of receivers located behind each takeoff and landing ground-roll segment

Extent: E+W+S+N.I.

The Δ SOR function described above mostly captures the pronounced directivity effect of the initial portion of the takeoff roll at locations behind the SOR (because it is the closest to the receivers, with the highest jet velocity to aircraft speed ratio). However, the use of the hence established Δ SOR is ‘generalised’ to positions behind each individual ground roll segment — both takeoff and landing —, so not only behind the Start-of-Roll point (in the case of takeoff).
The parameters dS and ψ are calculated relative to the start of each individual ground roll segment.
The event level Lseg for a location behind a given takeoff or landing ground-roll segment is calculated to comply with the formalism of the Δ SOR function: it is essentially calculated for the reference point located on the side of the start point of the segment, at the same distance dS as the actual point, and is further adjusted with Δ SOR to obtain the event level at the actual point.
This means that the different correction terms in the equations below shall use the geometric parameters corresponding to this reference point located on the side of the start point:
Lmax,seg = Lmax(P,d = ds) + ΔI(φ) – Λ(β,l = ds) + ΔSOR
(2.7.53)
LE,seg = LE,∞(P,d = ds) + ΔV + ΔI(φ) – Λ(β,l = ds) + Δ′F + ΔSOR
(2.7.54)
where Δ′ F is the reduced form of the noise fraction expressed in equation (2.7.46) for the case of q = 0 (as the reference point is located on the side of the start point) and remembering that dλ shall be calculated using dS (and not dp ):
d λ = d 0 × 10 L E∞ P,d s − L max P,d s ∕ 10
(2.7.55)

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Source: https://www.legislation.gov.uk/eudr/2015/996/annex/division/ASSESSMENT/division/2/division/2.7/division/2.7.19/division/9 (the official version)
Page: https://openlegislation.uk/eu-directive-2015-996/annex/division-ASSESSMENT/division-2/division-2.7/division-2.7.19/division-9
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.