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titlePage Table of Content

Table of Contents

Introduction

For Route Segment, PANS-AIM requires some basic properties as part of the minimum AIP data set. This is

..., startpointfrom point, endpointto point, track, distance, upper limit, lower limit, MEA, MOCA, ...

The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information:

Start Point & End Point

Route Segment ICAO defines a route segment as

A portion of a route to be flown usually without an intermediate stop, as defined by two consecutive significant points.

In AIXM 5, the start and the end properties of the RouteSegment class are used to define the "From point", i.e. the first point of the route segment and "To point", i.e. the second point of a route segment.

The EnrouteSegmentPoint class used for that purpose is a specialisation of the SegmentPoint. It provides the reportingATC attribute which is used for the indication of the ATS / MET reporting requirement 'COMPULSORY' or 'ON_REQUEST' for the corresponding point.

The actual start or end point of a RouteSegment is defined via the pointChoice property that allows to select a SignificantPoint. Not all available choices of significant points (e.g. RunwayCentrelinePoint, etc.) will make sense to be used for a route segment point (see also page SignificantPoint [SPN] ).

Mainly DesignatedPoint and Navaid will be the start or end point of a RouteSegment. In a few countries, also the airport reference point of an AirportHeliport may be used for that purpose.

For defining that the point used for the route segment is an RNAV waypoint (see also topic Designated Point (Overview)) the EnrouteSegmentPoint.waypoint attribute will be encoded with 'YES'.

...

Info
titleAIXM 5.2 Improvements

A change proposal (AIXM-532) for the next AIXM 5.2 version has been approved by the AIXM Change Control Board, which adds direct associations from InformationService, AirTrafficControlService, AirTrafficManagementService, and SearchAndRescueService towards RouteSegment.

The coding guidelines provided here are aligned with forward/backward conversion rules contained in the AIXM-532 Change Proposal.

From Point & To Point

ICAO defines a route segment as

A portion of a route to be flown usually without an intermediate stop, as defined by two consecutive significant points.

In AIXM 5, the start and the end properties of the RouteSegment class are used to define the "From point", i.e. the first point of the route segment and "To point", i.e. the second point of a route segment.

The EnrouteSegmentPoint class used for that purpose is a specialisation of the SegmentPoint. It provides the reportingATC attribute which is used for the indication of the ATS / MET reporting requirement 'COMPULSORY' or 'ON_REQUEST' for the corresponding point.

The actual start or end point of a RouteSegment is defined via the pointChoice property that allows to select a SignificantPoint. Not all available choices of significant points (e.g. RunwayCentrelinePoint, etc.) will make sense to be used for a route segment point (see also page SignificantPoint [SPN] ).

Mainly DesignatedPoint and Navaid will be the start or end point of a RouteSegment. In a few countries, also the airport reference point of an AirportHeliport may be used for that purpose.

For defining that the point used for the route segment is an RNAV waypoint (see also topic Designated Point (Overview)) the EnrouteSegmentPoint.waypoint attribute will be encoded with 'YES'.

In addition, AIXM 5 provides as an option to encode the extend of the route segment as geometrical element, using the Curve class. This data may be used for charting purposes. The curve will be encoded according to the corresponding GML specification (see topic Geometry (Overview)). It will contain the coordinates of the start and end point of the route segment. It shall be ensured that the data (i.e. coordinates) provided in the Curve element(s) match with those provided as start and end of the RouteSegment.

...

Tracks and reverse tracks if any, shall be encoded taking into account the implicit direction of the route segment, i.e. the defined start and end point, (see also above). In this regard, the tracks are from the start point of the segment, whereas the reverse tracks are from the end point of the route segment.

Infonote
titleOpen Question Radial as pathNote

AIXM 5.1.1 does not provide the possibility a dedicated value to define if the path between on the route segment is a VOR radial. Shall 'OTHER:VOR_RADIAL' may be used for RouteSegment.pathType be used for that purpose?.

The length attribute allows to define the distance of the path of the RouteSegment. The length depends on the pathType, which may be a great circle ('GRC'), a rhumbline ('RHL') or a geodesic line ('GDS'). According to

Note
titleNote
According to PANS-AIM, the length of a route segment shall be provided as geodesic distance.
Infowarning
Warning
titleAIXm 5.1(.1) issue
titleOpen question route segment path type
PANS-AIM requires geodesic, in AIPs very often you will find great circle, in case of a conventional route defined by VORs would the path type not rather be a Radial? TBD in the FG

PANS-AIM Appendix 1 also defines accuracy values the length. Also for the tracks but only for terminal arrival departure.

AIXM 5.1(.1) issue_006_RouteSegment.length

PANS-AIM defines an accuracy for the values for the length of an Route Segment. There is no dedicated attribute in AIXM 5.1.1.

Workaround fro AIXM 5.1(.1) does not provide a dedicated accuracy attribute for length. It can only be encoded using a corresponding annotation for the length attribute.

Warning
titlePANS-AIM issue

Unclear why PANS-AIM defines accuracy values for track in Table A1-3 ATS if it is only applicable for terminal arrival departure.

Lateral Limits

...

: A Note may be used to encode that information.

Status AIXM 5.2: See CCB AIXM-269.

Lateral Limits

For "ENR 3.1 Lower ATS routes" and "ENR 3.2 Upper ATS routes", PANS-AIM requires the provision of lateral limits.

...

According to ICAO Annex 11

:

The minimum flight altitudes determined shall provide a minimum clearance above the controlling obstacle located within the areas concerned.

...

ENR 3.1 (Lower ATS Routes):

  • upper and lower limits or minimum en-route altitudes.
  • minimum obstacle clearance altitudes;
  • Since en-route flights at or above the lowest usable flight level are flown at flight levels, it is suggested that these limits be expressed in flight levels (FL) whenever such flight levels are not likely to fall below the lowest safe altitude; otherwise, they should be expressed in altitude.

ENR 3.2 (Upper ATS Routes):

  • upper and lower limits (usually in flight levels "FL”).

ENR 3.3 (RNAV Routes):

  • upper and lower limits (usually in flight levels "FL”).

ENR 3.4 (Helicopter Routes):

  • upper and lower limits; minimum flight altitudes

ENR 3.5 (Other Routes):

  • No requirements stated regarding vertical limits.

The following table gives an overview which vertical limits are required by PANS-AIM for the AIP data set and the corresponding AIXM attributes of the RouteSegment class (Note 1):

. The lowermost vertical position at the end point, when flying on the route portion in the direction indicated in the RoutePortionUsage

According to PANS-AIM

The criteria used to determine minimum flight altitudes shall be provided in GEN 3.3.5.

In PANS-AIM the term is only used for "ENR 3.4 Helicopter routes"

ICAO Annex 11, 2.22 Minimum flight altitudes

Minimum flight altitudes shall be determined and promulgated by each Contracting State for each ATS route and control area over its territory. The minimum flight altitudes determined shall provide a minimum clearance above the controlling obstacle located within the areas concerned.

PANS-AIMAIXM 5.1.1
Remarks
PropertyDefinition/DescriptionRelevanceAttributeDescription
Upper limitThe upper limit of the route segmentENR 3.1-3.4upperLimitThe vertical position of the route segment ceiling.


Lower LimitThe lower limit of the route segmentENR 3.1-3.4 (Note 2)lowerLimitThe vertical position of the route segment floor.
Note
titleNote 2

According to PANS-AIM for ENR 3.1 Lower ATS Route,

lower limits or minimum en-route altitudes

shall be defined.

In the "old" ICAO Annex 15 it was

lower limits or minimum flight altitudes

Minimum obstacle clearance altitude (MOCA)The minimum altitude for a defined segment of flight that provides the required obstacle clearance. minimumObstacleClearingAltitudeENR 3.1 Lower ATS Route

minimumObstacleClearanceAltitude,

RouteSegment.annotation.Note.propertyNamevalue equal-to 'minimumObstacleClearanceAltitude'



Minimum obstacle clearance altitude (MOCA). The minimum altitude for a defined segment of flight that provides the required obstacle clearance.minimumEnrouteAltitude

According to ICAO PANS-OPSOPS 

A MOCA is determined and published for each segment of the route.

In PANS-AIM it is only required for ENR 3.1 Lower ATS Routes.

The MOC value to be applied in the primary area for the en-route phase of an IFR flight is 300 m (1 000 ft) as a minimum.

Minimum en-route altitude (MEA)The altitude for an en-route segment that provides adequate reception of relevant navigation facilities and ATS communications, complies with the airspace structure and provides the required obstacle clearance.ENR 3.1 Lower ATS Route (Note 2)

Warning
titleAIXM 5.1.1 issue_008_MOCA

PANS-AIM requires a accuracy to be specified for the MOCA. AIXM does not have a dedicated attribute for that purpose.

Workaround for AIXM 5.1(.1): Code a corresponding Note.

Status: For AIXM 5.2 see CCB AIXM-269.

Minimum en-route altitude (MEA)The altitude for an en-route segment that provides adequate reception of relevant navigation facilities and ATS communications, complies with the airspace structure and provides the required obstacle clearance.

According to PANS-OPS

The MEA is the greatest of:

  • the MOCA;
    • the minimum altitude for proper reception of the     		ENR 3.1 Lower ATS Route (Note 2)

    minimumEnrouteAltitude,

    RouteSegment.annotation.Note.propertyNamevalue equal-to 'minimumEnrouteAltitude'



    		Minimum en-route altitude (MEA). The altitude for an en-route segment that provides adequate reception of relevant navigation facilities and ATS communications, complies with the airspace structure and provides the required obstacle clearance.NANAminimumCrossingAtEnd

    According to ICAO PANS-OPS

    The MEA is the greatest of:

    • the MOCA;
    • the minimum altitude for proper reception of the relevant facilities;
    • the minimum altitude for proper reception of ATS communications;
    • the minimum altitude that complies with the ATS structure.
    Warning
    		Minimum flight altitudeMinimum flight altitudeENR 3.4 Helicopter routes???
    Info
    titleOpen Question Minimum Flight Altitude

    Isn't acc. to Annex 11 the MOCA and the Minimum flight altitude for Routes?

    Or is both the MEA and the MOCA considered as a kind of minimum flight altitude (see also change for ENR 3.1 Lower ATS routes?

    NA
    titleAIXM 5.1.1 issue007_MEA

    PANS-AIM requires a accuracy to be specified for the MEA. AIXM 5.1.1 does not have a dedicated attribute for that purpose.

    Workaround for AIXM 5.1(.1): Code a corresponding Note.

    Status: For AIXM 5.2 see CCB AIXM-269.

    Minimum flight altitudeMinimum flight altitudeENR 3.4 Helicopter routes


    minimumObstacleClearanceAltitude,

    RouteSegment.annotation.Note.propertyNamevalue equal-to 'minimumObstacleClearanceAltitude'



    According to PANS-AIM

    The criteria used to determine minimum flight altitudes shall be provided in GEN 3.3.5.

    In PANS-AIM the term is only used for "ENR 3.4 Helicopter routes"

    ICAO Annex 11, 2.23 Minimum flight altitudes

    Minimum flight altitudes shall be determined and promulgated by each Contracting State for each ATS route and control area over its territory. The minimum flight altitudes determined shall provide a minimum clearance above the controlling obstacle located within the areas concerned.


    RoutePortionUsage is not defined in AIXM
    Warning
    titleAIXM 5.1.1 issue
    _009_Minimum fight altitude

     AIXM 5.1.1 . If this attribute is related to the route portion, why is it part of the RouteSegment class?

    NANANAmaximumCrossingAtEndThe uppermost vertical position at the end point, when flying on the route portion in the direction indicated in the RoutePortionUsage.Same issue as above.

    does not have a dedicated attribute for that purpose.

    As, in PANS-AIM there is no definition for for Minimum flight altitude. For this mapping it is assumed that it may be the either the MEA or the MOCA for helicopters.

    Workaround for AIXM 5.1(.1): Code a RouteSegment.minimumObstacleClearanceAltitude, 
    or RouteSegment.minimumEnrouteAltitude.

    Status: To be reported to CCB

    Note
    titleNote 1
    PANS-AIM defines more vertical limits, i.e. Area Minimum Altitude (AMA) and Minimum Vectoring Altitude (MVA) which are not considered as part of the AIP Data set and hence are not contained in the table.
    Info
    titleOpen Question Lower limit Override

    In some State AIPs, an additional limit, "overriding" the Lower limit specification is published. To publish this minimum limit, often statements such as " but at least" are used. The Lower limit override always refers to ground e.g. "feet above ground".

    How to encode this in AIXM 5.1.1? in AIXM 4.5, a dedicated attribute was provided VAL_DIST_VER_LOWER_OVRDE

    Example:

    Image Removed

    Regarding the general encoding guidelines and rules for vertical limits see topic Vertical Limits.

    Coding Rules for Basic Data for Route Segment 

    ...

    Note
    titleNote
    To be clarified how PBN specification will be encoded.

    ...

    RouteSegment.start.EnRouteSegmentPoint.reportingATC is mandatory.

    ...

    Info
    titleOpen Question RSG-1-7

    To be clarified if also for ENR 3.4 Helicopter routes. Based on the open question for Minimum flight altitude property.

    ...

    Note
    titleNote
    This rule is suspended until clarified how PBN specification will be encoded.

    See also rule RSG-101

    ...

    Two consecutive route segments (of the same Route) should have vertical limits that, if not overlapping, should not be further away than 1000 FT. For example, if segment 1 is FL245 to FL295 and segment 2 is FL310 to FL490, (this rule will need to be adjusted based on operational experience).

    Image Removed

    ...

    The angle between two consecutive segments of the same route cannot exceed 90 degrees.

    Image Removed

    ...

    TBD

    Info
    titleOpen Question RSG_1-4
    This rule is based on the areas of responsibility defined in EAD. Shall there be a similar rules for the AIP data set based e.g.on FIR/UIR?

    ...

    Image Removed

    According to the rule definition the rule is violated, because four significant points "KPT", "TGO", "KRH" and "ECCHO" are used only once, either as start or end point of a route segment.

    ...

    Image Removed

    In the given example the rule is violated, because route segment "ECCHO - ANEKI" is described in the opposite order of the adjacent segments.

    ...

    Image Removed

    According to the rule definition the rule is violated, because ANEKI appears on three route segments.

    Subsequently this results in multiple branches; "ANEKI - ECCHO" and ANEKI - RUDUS".

    ...

    The position of the SignificantPoint used as the beginning of the RouteSegment must be separated by at least 30m (1 sec of arc) from the position of the SignificantPoint used as the end of the RouteSegment.

    Image Removed

    ...

    Info
    titleOpen Question RSG_1-5
    Is this rule justified by an ICAO doc?

    ...

    The value of EnRouteSegmentPoint.reportingATC for RouteSegment.start and RouteSegment.end of any two consecutive segments of the same route must be consistent.

    ...

    The difference between length and the calculated length of the related RouteSegment cannot exceed 5 KM.

    Image Removed

    ...

    Info
    titleOpen Question RSG 1-6
    PANS-AIM requires an accuracy of 1/10 KM. Shall the rule be changed accordingly?

    ...

    The difference between Initial trueTrack and the calculated initial true track of the related RouteSegment cannot exceed 2 degrees.

    The difference between reverseTrueTrack and the calculated reverse initial true track of the related RouteSegment cannot exceed 2 degrees.

    Image Removed

    ...

    Regarding the general encoding guidelines and rules for vertical limits see topic Vertical Limits.

    Level

    Although this information is not explicitly required by PANS-AIM it should be coded at least for route segments published in an AIP in Section ENR 3.1 Lower ATS routes and  ENR 3.2 Upper ATS Routes, with 'LOWER' and 'UPPER' respectively. This is also relevant as some Coding Rules relate on this information (see below).

    Coding Examples

    The figure below gives a simple example of the encoding of the route segment from "DINKI" to "LNO".

    ...

    The figures below give an example of the encoding of the route segment (from "BARIM" to "WOB"), including the mapping from AIXM UML to AIXM XML.

    Image Removed

    Image Removed

    More coding examples can be found in the AIXM DONLON AIP data set.

    ...

    TBD

    .

    Image Added

    Image Added

    More coding examples can be found in the AIP Data Set - Specimen (DONLON).

    TBD
    No.DescriptionXPath Expression

    RSG-EX-01

    RSG-EX-04

    Route segment of Lower ATS route (incl.  MEA)

    Route segment of Lower ATS route (incl. MOCA)

    //aixm:RouteSegmentTimeSlice[@gml:id='RSG_A6_BOR_ROB'] |

    //aixm:RouteSegmentTimeSlice[@gml:id='RSG_A6_ROB_ROK']

    RSG-EX-02Route segment of Upper ATS route//aixm:RouteSegmentTimeSlice[@gml:id='RSG_UA4_BARIM_WOB']
    RSG-EX-03Route segment of RNAV route//aixm:RouteSegmentTimeSlice[@gml:id='RSG_UL123_ABOLA_ILURU']RSG-EX-04Route segment of Helicpoter route

    References