Introduction
For Waypoint – en-route (designated point) PANS-AIM requires some basic properties as part of the minimum AIP data set. These are
identification, location, formation;
AIP Context
The example below shows En-route Waypoints as they may be published in ENR 4.4.
The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information:
Identification (designator & name)
Each DesignatedPoint shall have a designator. In AIXM 5, the designator is limited to a combination of maximum 5 alphabetic and numeric characters.
ICAO Annex 11, Appendix 2 determines the rules of how to create designators for significant points not marked by the site of a radio navigation aid:
Where a significant point is required at a position not marked by the site of a radio navigation aid, and is used for ATC purposes, it shall be designated by a unique five-letter pronounceable “name-code”.
This name-code designator then serves as the name as well as the coded designator of the significant point...
...The unique five-letter pronounceable name-code designator assigned to a significant point shall not be assigned to any other significant point.
These are the designated points which are published in ENR 4.4; Examples: ADOLA, KODAP
However, in the scope of the definition of start and end point for route segments also points which do not have an allocated 5 Letter Name Code (5LNC) are used and published (e.g. defined just by coordinates).
For a designated point which does not have an officially allocated 5LNC, e.g. intersection defined by distance and bearing, point with identifier derived from its geographical coordinates, VFR reporting points, certain naming conventions (e.g. based on ARINC 424) may be applied to create the designator.
In addition to the designator, also a textual name of a designated point, such as 'GOTAN Intersection' for a point with designator GOTAN, may be encoded using the name property. For the points that have a 5LNC, the same value should be coded as both designator and name. This is based on the ICAO Annex 11, Appendix 2 provision which says that "This name-code designator then serves as the name as well as the coded designator of the significant point...". The name attribute may also be used to identify an unnamed point.
Location
The geographical location of a DesignatedPoint is defined by the Point class.
PANS-AIM defines a horizontal accuracy for en-route waypoints. The horizontalAccuracy attribute is used for that purpose.
For detailed encoding of the geographical position of a point refer to the topic Geometry/Point.
Formation
See topic Point Reference (Formation) [PRF].
Type
A type property for waypoints (designated points) is not known by ICAO Annex 15 nor PANS-AIM.
AIXM defines a type attribute for the DesignatedPoint feature as follows:
The kind of point designator, indicating the rules by which the designator has been created.
Note
In AIXM 5.1.1, the class CodeDesignatedPointBaseType provided a set of values for the type. Not all of them are relevant for the enroute environment.
For en-route waypoints only 'ICAO', 'COORD', 'BRG_DIST''and 'OTHER', if needed should be used.
| Value | Description |
|---|---|
| 'ICAO' | ICAO 5 letter name code designator. |
| 'COORD' | Point with identifier derived from its geographical coordinates. |
| 'CNF' | Computer Navigation Fix - A point used for the purpose of defining the navigation track for an airborne computer system (i.e., GPS or FMS). CNFs include unnamed DME fixes, beginning and ending points of DME arcs and sensor final approach fixes (FAFs) on some GPS overlay approaches. |
| 'DESIGNED' | A point with bearing/distance designator used as control point for procedure design, which is not published. |
| 'MTR' | Point used on a military training route. |
| 'TERMINAL' | Point with a five-alphanumeric name-code, used as waypoint in RNAV procedures and which does not have a globally unique ICAO 5-letter designator. |
| 'BRG_DIST' | Point with a five-alphanumeric name-code, composed according to the rules provided by the ARINC 424 Specification for unnamed bearing/distance reference waypoints. |
| 'OTHER' | Other. |
Coding Guidelines for Types of Designated Points
Although type is not part of PANS-AIM, but a similar data field is used by ARINC 424, some guidelines shall be provided how to code different types of designated points that a may be used in the en-route environment.
ARINC 424 naming conventions are applied, where appropriate. (This guidelines are limited to en-route relevant designated points. For the full scope of the ARINC 424 naming convention, see the ARINC 424 Specification .)
| Designated Point used in the en-route environment | AIXM 5 | |||
|---|---|---|---|---|
| designator | type | name | Remarks | |
| Point with five-letter name-code (5LNC) | 5LNC | 'ICAO' | 5LNC | Example: designator equal-to 'BERTA' name equal-to 'BERTA' |
| Reporting Positions Defined by Coordinates | according ARINC 424 naming convention | 'COORD' | nil="true" | Entry, Exit, and intermediate points within Oceanic Control Areas are often defined by waypoints which are undesignated, meaning there is no published five-lettername-code. Example: point with coordinates N5200/W07500 designator equal-to '5275N' name nil="true", nilReason="inapplicable" Example: point with coordinates N0600/E11000 designator equal-to '06E10' name nil="true", nil="true", nilReason="inapplicable" Example: point with coordinates S7500/E05000 designator equal-to '7550S' name nil="true", nil="true", nilReason="inapplicable" |
| Named RNAV Waypoints, Intersections, and Reporting Points | according ARINC 424 naming convention | 'OTHER:' with appropriate type | as source provided | A. If five or less characters are involved, use the full name. Examples: ACRA designator equal-to 'ACRA' name equal-to 'ACRA' B. If the name is more than five characters, reduce to five characters according ARINC 424. Examples: BRIDGEPORT designator equal-to 'BRIDT' name equal-to 'BRIDGEPORT' CLEAR LAKE designator equal-to 'CLAKE' name equal-to 'CLEAR LAKE' |
| Unnamed turn points, intersections, and bearing/distance waypoints | according ARINC 424 naming convention | for named turn points, intersections: 'OTHER:' with appropriate type for bearing/distance waypoints 'BRG_DIST' | according ARINC 424 naming convention | Designator is constructed by taking the identifier code of the reference NAVAID for the turn point/intersection/(bearing/distance waypoint) and the distance from the NAVAID to the turn point/intersection/(bearing/distance waypoint). Name is constructed by the forming NAVAID identifier and bearing/distance information. Examples: NAVAID IDENT, BEARING, DISTANCE INW, 090 degrees, 18.4 NM designator equal-to 'INW18' name equal-to INW090018 CSN, 180.5 degrees, 106 NM designator equal-to '06CSN' name equal-to 'CSN181106' |
Coding Examples
The figures below give a simple example of the encoding of designated points as published in an AIP in section ENR 4.4:
UML to XML: Designated Point:
Coding examples can be found in the AIP Data Set - Specimen (DONLON):
| No. | Description | XPath Expression |
|---|---|---|
| DPN-EX-01 | Point with five-letter name-code (5LNC) | //aixm:DesignatedPointTimeSlice[@gml:id ='DPN_TEMPO'] |
| DPN-EX-02 | Point with five-letter name-code (5LNC) | //aixm:DesignatedPointTimeSlice[@gml:id ='DPN_ABOLA'] |
| DPN-EX-03 | Reporting Position Defined by Coordinates | //aixm:DesignatedPointTimeSlice[@gml:id ='DPN_5275N'] |
| DPN-EX-04 | Named Reporting Point (more than 5 letters) | //aixm:DesignatedPointTimeSlice[@gml:id ='DPN_TORSA'] |
| DPN-EX-05 | Unnamed bearing/distance waypoint | //aixm:DesignatedPointTimeSlice[@gml:id ='DPN_BOR10'] |
| DPN-EX-05 | ARP as designated point | //aixm:DesignatedPointTimeSlice[@gml:id ='DPN_EADH'] |