Division The local coordinate system
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The local coordinate system (x,y,z) is a Cartesian one and has its origin (0,0,0) at the aerodrome reference point (XARP,YARP,ZARP ), where ZARP is the airport reference altitude and z = 0 defines the nominal ground plane on which contours are usually calculated. The aircraft heading ξ in the xy-plane is measured clockwise from magnetic north (see Figure 2.7.b). All observer locations, the basic calculation grid and the noise contour points are expressed in local coordinatesf1.
Figure 2.7.b
Local coordinate system (x,y,z) and ground-track fixed coordinate s
Annotations
Footnotes
- f1
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Usually the axes of the local coordinate are parallel to the axis of the map that contours are drawn on. However it is sometimes useful to choose the x-axis parallel to a runway in order to get symmetrical contours without using a fine computational grid (see Sections 2.7.26 to 2.7.28).