The horizontal boundary of some airspace may be derived from the horizontal boundary of another airspace. A typical examples are UIR that inherit the horizontal limits of an FIR.
The geometry of such (dependent) airspace can be coded with a single AirspaceVolume, which has its own vertical limits but which does not have its own horizontalProjection. Instead, the AirspaceVolume needs the contributorAirspace and its AirspaceVolumeDependency association class properties . Two possibilities exist:
only the horizontal projection of the 'parent' Airspace is inherited(
AirspaceVolumeDependency.dependency
equal-to= 'HORZ_PROJECTION').
This is the case for most such airspace. In this case, the AirspaceVolume properties for vertical limits (lowerLimit, upperLimit, etc.) will need also to be coded in order to fully define its geometry);the full geometry of the 'parent' Airspace is inherited (AirspaceVolumeDependency.dependency equal-toNote that the operation and operationSequence attributes of the AirspaceComponentGeometry association class shall not be left empty. They should get the values 'BASE' and '1', respectively.
Note: The model offers an additional (theoretical) possibility - that an AirspaceVolume inherits the complete geometry (both horizontal projection and vertical limits) of another Airspace (dependency = 'FULL_GEOMETRY').
In this case, which is not very common, the AirspaceVolume properties for vertical limits will be left empty.In both situations described above the attributes of the association class AirspaceComponentGeometry (i.e. operation and operationSequence) will not be left empty. However, there are no known usages of this possibility for single volume airspace. This possibility is expected to be used only for airspace defined with Multiple volumes.
Coding Example
The figure below shows a simple example of such an airspace.
The lateral limits of the UIR YORK NEW are derived from the horizontal projection defined for the FIR YORK NEW. Dedicated vertical limits (FL 180 - UNL) are defined for the UIR YORK NEW.
| Note | ||
|---|---|---|
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This is a fictitious example part of the AIXM DONLON Specimen 2022. |
| Code Block | ||||||
|---|---|---|---|---|---|---|
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<!-- FIR YORK NEW -->
<aixm:Airspace gml:id="uuid.b75a32cf-65da-4028-81f2-70ad30072736">
...
<aixm:type>FIR</aixm:type>
<aixm:designator>KAAD</aixm:designator>
<aixm:name>YORK NEW</aixm:name>
<aixm:designatorICAO>YES</aixm:designatorICAO>
<aixm:class>
<aixm:AirspaceLayerClass gml:id="alc0001">
<aixm:annotation>
<aixm:Note gml:id="n0001">
<aixm:propertyName>classification</aixm:propertyName>
<aixm:purpose>REMARK</aixm:purpose>
<aixm:translatedNote>
<aixm:LinguisticNote gml:id="ln00011">
<aixm:note>Outside regulated airspace.</aixm:note>
</aixm:LinguisticNote>
</aixm:translatedNote>
</aixm:Note>
</aixm:annotation>
<aixm:classification>G</aixm:classification>
</aixm:AirspaceLayerClass>
</aixm:class>
<aixm:protectedRoute xsi:nil="true"/>
<aixm:geometryComponent>
<aixm:AirspaceGeometryComponent gml:id="A-cd43e44a">
<aixm:theAirspaceVolume>
<aixm:AirspaceVolume gml:id="A-c3969fee">
<aixm:upperLimit uom="FL">180</aixm:upperLimit>
<aixm:lowerLimit>GND</aixm:lowerLimit>
<aixm:horizontalProjection>
<aixm:Surface srsName="urn:ogc:def:crs:EPSG::4326"
gml:id="s0010">
<gml:patches>
<gml:PolygonPatch>
<gml:exterior>
<gml:Ring>
<gml:curveMember>
<gml:Curve gml:id="c0010">
<gml:segments>
<gml:GeodesicString>
<gml:posList>57.0833333333333 -40
52.85 -41.7833333333333
48.4666666666667 -41.3333333333333
44.0333333333333 -40
42.6 -37
40.7333333333333 -37.1833333333333
41.8765247129238 -52.7268162084394
56.1244400919614 -46.3306297361232
57.0833333333333 -40</gml:posList>
</gml:GeodesicString>
</gml:segments>
</gml:Curve>
</gml:curveMember>
</gml:Ring>
</gml:exterior>
</gml:PolygonPatch>
</gml:patches>
<aixm:horizontalAccuracy uom="KM"
>2.0</aixm:horizontalAccuracy>
</aixm:Surface>
</aixm:horizontalProjection>
</aixm:AirspaceVolume>
</aixm:theAirspaceVolume>
</aixm:AirspaceGeometryComponent>
</aixm:geometryComponent>
</aixm:AirspaceTimeSlice>
</aixm:timeSlice>
</aixm:Airspace>
<!-- UIR YORK NEW, derived geometry from FIR YORK NEW -->
<aixm:Airspace gml:id="uuid.6fa9b51a-ea66-40a7-a23a-058c3a034719">
<gml:identifier codeSpace="urn:uuid:">6fa9b51a-ea66-40a7-a23a-058c3a034719</gml:identifier>
...
<aixm:type>UIR</aixm:type>
<aixm:designator>KAAD</aixm:designator>
<aixm:name>YORK NEW</aixm:name>
<aixm:designatorICAO>YES</aixm:designatorICAO>
<aixm:class>
<aixm:AirspaceLayerClass gml:id="alc1001">
<aixm:classification>C</aixm:classification>
</aixm:AirspaceLayerClass>
</aixm:class>
<aixm:protectedRoute xsi:nil="true"/>
<aixm:geometryComponent>
<aixm:AirspaceGeometryComponent
gml:id="data1000212">
<aixm:operation>BASE</aixm:operation>
<aixm:operationSequence>1</aixm:operationSequence>
<aixm:theAirspaceVolume>
<aixm:AirspaceVolume gml:id="data1000424423">
<aixm:upperLimit>UNL</aixm:upperLimit>
<aixm:lowerLimit uom="FL">180</aixm:lowerLimit>
<aixm:contributorAirspace>
<aixm:AirspaceVolumeDependency
gml:id="data100024324">
<aixm:dependency>HORZ_PROJECTION</aixm:dependency>
<aixm:theAirspace xlink:href="urn:uuid:b75a32cf-65da-4028-81f2-70ad30072736" xlink:title="FIR YORK NEW"/>
</aixm:AirspaceVolumeDependency>
</aixm:contributorAirspace>
</aixm:AirspaceVolume>
</aixm:theAirspaceVolume>
</aixm:AirspaceGeometryComponent>
</aixm:geometryComponent>
</aixm:AirspaceTimeSlice>
</aixm:timeSlice>
</aixm:Airspace> |
| No. | Description | XPath Expression |
|---|---|---|
| ASE-EX-20 | UIR with derived lateral limits from FIR (Single volume with derived geometry) | //aixm:AirspaceTimeSlice[@gml:id='ASE_YORKNEW_UIR'] |