Introduction
For Route Segment, PANS-AIM requires the direction of cruising level and reverse direction of cruising level as part of the minimum AIP data set.
The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information:
The RouteAvailability class is used to define the direction of the RouteSegment. AIXM provides the possibility to encode if a route segment may be available for just one direction, i.e. 'FORWARD', or 'BACKWARD', or 'BOTH' directions.
The value 'OTHER' should not be used. Also 'BOTH' should be avoided as for the different direction a different level series will apply. In case a of a bidirectional route, two records shall be encoded - one for forward and one for backward.
The StandardLevelColumn class is used to define the series of levels. In general, the value used will either be 'ODD' or 'EVEN'. 'ODD_HALF' and 'EVEN_HALF' are used for intermediate flight levels, above odd levels (15, 35, 55, 75, ...) or above even levels (5, 25, 45, 65, ...).
The directions forward and backward are related to the implicit direction of a route segment (see topic Basic Data of Route Segment). 'FORWARD' means from the defined start point towards the end point of the related RouteSegment. 'BACKWARD' means from the defined end point towards the start point of the related RouteSegment.
Forward/Backward is equivalent to the little arrow that appears in the ENR 3.x tables in the AIP, to indicate the direction of flight which is concerned by odd/even.
In addition, the AirspaceLayer class may be used to encode limitations on the vertical levels. In case the AirspaceLayer class is used to encode vertical limits, they shall correspond with the values specified in the StandardLevelColumn.
OPEN Question RSG Airspace layer
Should the airspace layer be encoded with the same FL as the route segment upper and lower limit? Should there be a rule?
Still open discussion if Class is attribute of Route or surrounding Airspace.
Coding Rules for Direction of Cruise Levels
| Identifier | Data Encoding Rule | Justification | Data Verification Rule (UID) | Remarks |
|---|---|---|---|---|
| RSG-301 | Each Route.Segement shall have as minimum one and as maximum two related RouteAvailability.direction. | Minimum AIP data set | AIXM-5.1_RULE-1A339D (does not include the maximum constraint) | |
| RSG-302 | The value of the RouteAvailability.direction of the same Route.Segement may not have the same value. | Data consistency | TBD | |
| RSG-303 | For each RouteAvailability one and only one discreteLevelSeries shall be provided. | Minimum AIP data set | TBD | The StandardLevelColumn defines if the route segment is flown odd or even. |
| RSG-304 | For RouteAvailability.direction the values 'BOTH' and 'OTHER' shall not be used. | Data consistency | TBD | In case a of a bidirectional route, two records shall be encoded - one for forward and one for backward. |
Coding Examples
More coding examples can be found in the DONLON AIP data set file:
| No. | Description | XPath Expression |
|---|---|---|
| RSG-EX-01 | Route segment of Lower ATS route with forward & backward with FL series Even & Odd respectively. | //aixm:RouteSegmentTimeSlice[@gml:id='RSG_A6_BOR_ROB'] | |
| RSG-EX-02 | Route segment of Upper ATS route with forward & backward with FL series Even & Odd respectively. | //aixm:RouteSegmentTimeSlice[@gml:id='RSG_UA4_BARIM_WOB'] |
| RSG-EX-03 | Route segment RNAV Route with direction forward & backward with FL series Even & Odd respectively. | //aixm:RouteSegmentTimeSlice[@gml:id ='RSG_UL123_ABOLA_ILURU'] |