Introduction
PANS-AIM requires the change over point (COP) to be encoded in case the path of the route segment(s) is a VOR radial. This is applicable only for conventional routes, i.e. for ENR 3.1 Lower ATS Routes, ENR 3.2 Upper ATS Routes and ENR 3.4 Helicopter routes.
PANS-AIM defines the COP as:
The point at which an aircraft navigating on an ATS route segment defined by reference to very high frequency omni directional radio ranges is expected to transfer its primary navigational reference from the facility behind the aircraft to the next facility ahead of the aircraft.
AIXM 5.1(.1) defines the ChangeOverPoint class as follows:
The distance from the start of the route portion to the position where change over occurs for VOR defined routes
In AIXM 5.1.1, the ChangeOverPoint is related to a RoutePortion and not a route segment. Hence, to encode COP information, also a corresponding RoutePortion has to be encoded. The ChangeOverPoint.applicableRoutePortion is used for that purpose.
The ChangeOverPoint.distance attribute is used to define the distance from the RoutePortion.start to position of the change over point. Only the distance from the start of the route portion is encoded.
The distance from the end of the route portion can be derived from the length defined by the start and end of the RoutePortion or be encoded as a Note for the ChangeOverPoint.
The ChangeOverPoint.location may be used to define the position of COP as SignificantPoint. In this regard, only Point shall be used as SignificantPoint.
AIP context
In the AIP information about the COP may be published in section ENR 3 or on en-route charts.
Coding Rules for Change Over Point
| Identifier | Data Encoding Rule | Justification | Data Verification Rule (UID) | Remarks |
|---|---|---|---|---|
| RSG-501 | The SignificantPoint used as start of the RoutePortion as ChangeOverPoint shall be either a Navaid.type equal-to 'VOR_DME' or 'TACAN' or 'VORTAC'. | Data consistency | TBD | |
| RSG-502 | The SignificantPoint used as end of the RoutePortion as ChangeOverPoint shall be either a Navaid.type equal-to 'VOR_DME' or 'TACAN' or 'VORTAC'. | Data consistency | TBD | |
| RSG-503 | If a SignificantPoint is used for the ChangeOverPoint.location it shall be a Point. | Data consistency | TBD | |
| RSG-504 | The ChangeOverPoint.distance shall be the distance from the start of the related RoutePortion. | Data consistency | TBD |
Coding Examples
Coding Examples can be found in the AIP Data Set - Specimen (DONLON).
| No. | Description | XPath Expression |
|---|---|---|
| COP-EX-01 | Change over point | //aixm:ChangeOverPointTimeSlice[@gml:id ='COP_WOB_EKO'] |