For ATS airspace and for special activity airspaces, PANS-AIM requires the lateral limits to be provided as part of the minimum AIP data set. The diagram below shows the AIXM classes that may be used for coding this data:
There are two main ways to describe the geometry of airspace volumes in AIXM:
- by directly providing a horizontal border and vertical limits;
- Horizontal Border
- described as horizontalProjection (Surface)
- described by a AirspaceVolume.width and a centreline (Curve), for airspace corridors
- Vertical limits defined in AirspaceVolume class
- Horizontal Border
- through a composition rule by which the airspace is defined as a series of unions, intersections, subtractions of other Airspace (aggregation) using the AirspaceComponentGeometry operation attributes and/or the AirspaceVolumeDependency association classes.
The model gives the possibility for using several approaches for the encoding of airspace aggregations/dependencies. The use of a method from the ones described further down in this section, depends on the intended use of the data. Examples of the application of such airspace aggregations are:
- Airspace of type CTR defined as a “circle of 50 NM from which the portion of airspace situated in a neighbouring FIR is subtracted”;
- Airspace of type UIR that has “the same horizontal projection as an FIR”, but different vertical limits;
- Airspace of type CTA which is the result of aggregating some Airspace of type SECTOR;
- etc.
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A change proposal (AIXM-566) for the next AIXM 5.2 version has been approved by the AIXM Change Control Board, which adds an association from AirspaceVolume to Point with location role. This facilitates the coding of airspace warnings, such as Parachute Jumping Exercise (PJE), glider activity, etc. which have a point location, without specified lateral limits. The coding guidelines provided here are aligned with forward/backward conversion rules contained in the AIXM-566 Change Proposal. |
An overview of the encoding of geometries in AIXM 5 is can also be found on the Geometry page of this documentation.
The attributes of the AirspaceVolume class are used to define the vertical limits of the airspace (see also Vertical Limits of Airspace). In addition, a horizontalProjection (lateral limits) will be encoded using the Surface class.
In case of an airspace corridor, a centreline will be defined using the Curve class.
The Surface of the airspace may use SignificantPoint and/or GeoBorder for its definition (see also the topics Significant Point for Airspace Border and GeoBorder).
The example below shows the Special Rule Airspace (SRA) WIEN IV with the vertical limits from 4500 FT AMSL up to FL 195.
The lateral limits are defined by several points and types of path between them. Between P1 and P2 the state border between Austria and the Czech Republic is referenced. Between P2 and P3 it is the state border between Austria and Slovakia. From P3 to P4 a DME Arc based on the VOR/DME "FMD" is used to define the airspace border. From P4 to P5 a geodesic line defines the lateral limits. P5 to P6 is again defined by an DME arc. From P6 to P7 again a geodesic line is used. Finally, the airspace border is closed by a geodesic line between P7 and P1.
Coding Examples
See child pages.
Child Pages
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