Copyright © 2010 Open Geospatial Consortium, Inc. All Rights Reserved.
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Figure 9 — Close-up of hatched filled Runway with Right and without Left additional outline
Figure 10 — Zoomed out view of hatched filled Runway with Right and without Left additional outline
7.3.1.3 Recommendations – Unserviceable features
Proposed symbols for indicating unserviceable navaids. Unservicable could be indicated by an overlay symbol consisting of a circle with a strike-through, angled 45 degrees
referenced to the graphical display. To enhance contrast between symbol and overlay, the overlay below has a white outline, which also enhances readability in black and white or
print for example. See figures below for suggested icons.
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Copyright © 2010 Open Geospatial Consortium, Inc. All Rights Reserved.
Table 1 - Unserviceable features Icon
Comment
Unservicable NDB with red overlay, smaller than the bounds of the original
symbol.
Unservicable NDB with black overlay, larger than the bounds of the original symbol. Makes for a rather large symbol
unfortunately.
Unservicable TACAN with red overlay, smaller than the bounds of the original symbol.
Unservicable TACAN with red overlay, larger than the bounds of the original symbol.
Unservicable TACAN with black overlay, smaller than the bounds of the original symbol.
Unservicable TACAN with black overlay, larger than the bounds of the original symbol.
Figure 11 - Unserviceable navaids
Copyright © 2010 Open Geospatial Consortium, Inc. All Rights Reserved.
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7.3.2 Contamination 7.3.2.1 Problem
The ICAO Annex 4 contains no recommendation on how to portray contamination of surfaces, such as runways and taxiways.
7.3.2.2 Recommendations
In the digital SNOWTAM trial of Eurocontrol a triangular icon was used to indicate contaminations. The icon had a fill color based on friction estimate, and also showed the
friction estimate together with the type of contaminant. Next to the icon, the extent of the upper contaminant layer was also visualized with a fill color based on contamination
type. Se figures below.
Figure 12 — SNOWTAM symbols.
Figure 2 — Multiple layer contamination icon.
Contaminations are modeled as sub-objects of features, similar to light elements or markings. This means that we also have to use a hierarchical symbolizer.
7.3.2.2.1 Contamination data
Even if a surface has two or more layers with different horizontal projections, they should still be modelled as one SurfaceContamination, with several SurfaceContaminationLayer,
but with different associated ElevatedSurface features. Thats because there is only one observationTime. I this case a multiple layer symbol should be placed in the
geometrical centre of the uppermost layer. The other ones should not be very different.
There is ongoing work on guidelines for runway friction measurement and reporting. This will most likely affect the SurfaceContamination model further.
