Supporting material for ICAO Aerodrome Mapping Data Sets
This section provides ‘TaxiwayHoldingPosition’ feature data encoding guidance.
AMD data encoding can start when the necessary geographic information, aeronautical information and basic knowledge regarding the structure of the created feature is available.
From the geographical point of view, the TaxiwayHoldingPosition is a line where taxiing aircraft and vehicles shall stop and hold until further cleared by ground control. For TaxiwayHoldingPosition two points shall be measured to capture the line. The key attributes are the longitude, latitude and the elevation in reference with WGS-84. In the next part the process of converting the geographical information into GML form, thus into geometry information, is described.
Based on Aeronautical Data Catalogue the required type of geometry for the TaxiwayHoldingPosition is the line. The definition of line can be found in the Table A1-9 Data types of the Aeronautical Data Catalogue.
TaxiwayHoldingPosition is mapped to the AIXM 5.1 as feature TaxiHoldingPositionMarking.
In AIXM 5.1 the TaxiHoldingPosition is a general operational concept which allows for the encoding of a point whereas in the AMD a line is used. This is the reason why the AIXM 5.1 TaxiHoldingPositionMarking is used to encode the line geometry (1 or more). The AIXM 5.1 TaxiHoldingPositionMarking also encodes a relation to the AIXM 5.1 TaxiHoldingPosition. The line that is captured can represent the real world feature. Careful consideration is needed when not all marking elements that constitute a single TaxiHoldingPositionMarking are captured. If a single line element is provided the operationally significant geometry shall be captured for safety reasons. Further details on these digitizing considerations are out of scope of this supporting material.
In the AIXM 5.1 the geometry of the TaxiHoldingPositionMarking is curve encoded as object ElevatedCurve.
For more information regarding AIXM 5.1 Geometry encoding follow 'AIXM data coding'.
AIXM 5.1 is based on GML. Hence, obtained geographical locations shall be transferred into a GML geometry object GeodesicString
Figure 1 : TaxiwayHoldingPosition
Feature Runway TaxiwayHoldingPosition shall be established in accordance with coding rules and requirements listed in AIXM 5.1 Temporality Model.
AIXM 5.1 features
TaxiwayHoldingPosition is encoded to the AIXM 5.1 as feature TaxiHoldingPositionMarking.
All associations are shown in the UML Diagram (see below).
UML Diagram (Markings/Surface Marking)
Content of example
The following AMD properties are not covered in the AIXM 5.1. coding example: vres, hres, integr, holddir, marktype, rwelight, aippub, lvo. These are covered by an AIXM 5.1. extension.
Coding example - Structure of message
Coding example - AIXM 5.1
Download feature TaxiwayHoldingPosition: