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 convetional 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.
In AIXM 5.1.1 the ChangeOverPoint is related to a RoutePortion and not a route segment. Hence, in order to encode COP information also a corresponding RoutePortion has to be encoded.
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 defiend by the start and end of the RoutePortion or b eencoded 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.
Coding Rules for Change Over Point
| RSG-501 | The SignificantPoint used as start and end of the RoutePortion a ChangeOverpoint is applicable to shall be a VOR or TACAN. | Data consistency | TBD | . |
| RSG-502 | The SignificantPoint used for the ChangeOverPoint.location shall be a Point. | Data consistency | TBD | |
| RSG-503 | The ChangeOverPoint.distance shall be the distance from the start of the related RoutePortion. | AIXM 5.1.1 | TBD |
Coding Examples
The figure below gives a simple example of a change over point:
More Examples TBD in teh scope of teh DONLON AIP data set XML.