Airspace boundaries may be based on national borders or on other geographical features, such as shorelines, rivers, etc.
A particularity of this situation is that official definitions of the airspace, as provided in the Aeronautical Information Publication (AIP) or in NOTAM messages, do not include the actual geometry of the referenced geographical border. It is left for the end users to derive the actual geometry of the airspace by using a source of geographical border data.
The UML model of AIXM shows a “dependency” association between Surface and GeoBorder in order to cater for such situations
The encoding is possible in two ways: either with a simple annotation (and copy of all necessary points) or by reference. See the AIXM GML Guidelines for details.
Coding Examples
