target version:

AIXM 5.2



last updated:

24 OCT 2019




A new object for AltitudeIndication is added in relation with RouteSegment, allowing to code multiple MEA values, based on direction and aircraft equipment.

Rationale for change


Business requirement exists for more than one Minimum En-route Altitudes (MEA). Currently, the AIXM Enroute model does not support multiple MEA(s).

A few examples of routes from the AIP are available to show the existence of multiple MEAs. There is also a business requirement for a Global Navigation Satellite System Minimum En-route IFR Altitude (GNSS MEA) - The minimum en route IFR altitude on a published ATS route or route segment which assures acceptable GNSS reception and meets obstacle clearance requirements.

Also, for similarity with the route availability model, a cardinalDirection property is necessary. For example, route  V327 has three MEAs at FERER - N 12000, S 11000, GNSS MEA - 9000.

To be able to pass multiple MEA(s), a new object for AltitudeIndication  is added to the model with altitude, cardinalDirection, navigationEquipment, and direction properties.

Impact assessment

[FWD_MAP_1:1] Data mapping is possible and no data loss occurs when data is exchanged from a system (A) that uses AIXM 5.1.1 for output towards a system (B) that uses AIXM 5.2 for input.

[BWD_MAP_LOSS] Data mapping is possible, but some data would be lost (or converted into Notes) when data is exchanged from a system (B) that uses AIXM 5.2 for output towards a system (A) that uses AIXM 5.1.1 for input.

Change Proposal details

In the UML model:

    • Add a new class AltitudeIndication with <<object>> stereotype, definition = “Flight altitude value based on fight directions and navigation equipment used on an aircraft.”.
      • Attributes:
        • altitude of type ValDistanceVerticalType, definition = “The value of the altitude.”
        • cardinalDirection of type CodeCardinalDirectionType, definition = “An indicator of the general cardinal direction of the segment.”
        • navigationEquipment of type CodeNavigtionEquipmentType, definition = “A type of navigation equipment capability associated with the use of the altitude.”
        • direction of type CodeDirectionType, definition = “An indicator of the direction of the segment”.
    • Associations:
      • RouteSegment isLimitedBy AltitudeIndication , navigable towards AltitudeIndication, role “minimumEnrouteAltitude” and defines a zero-to-many relationship from RouteSegment Feature to the AltitudeIndication Object. Definition = “The lowest published 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.
  • Delete the RouteSegment.minimumEnrouteAltitude attribute as it will be present in the AltitudeIndication object.

The changes are visible in the UML class diagram to the right.

Mapping AIXM 5.1.1 to AIXM 5.2 (forward)

[MAPC-04] The following algorithm shall be applied:

For each RouteSegment has minimumEnrouteAltitude value:

  •  Remove the EnrouteSegment.minimumEnrouteAltitude.
  • Copy minimumEnrouteAltitude value into minimumEnrouteAltitude.AltitudeIndication.altitude.
  • Do not add value to minimumEnrouteAltitude.AltitudeIndication.cardinalDirection.
  • Do not add value to minimumEnrouteAltitude.AltitudeIndication.navigationEquipment.
  • Add ‘BOTH value to minimumEnrouteAltitude.AltitudeIndication.direction.

Mapping AIXM 5.2 to AIXM 5.1.1 (backward)

[MAPC-04] From the three backward mapping options discussed for MAPC-04, the first two (discard the values or use an extension) are straightforward and do not need any further details. The 3rd option (backward mapping into the old property, complemented with a Note) is detailed in order to provide a complete description of this case and its conversion option. The following mapping into Note algorithm is proposed:

For each occurrence of minimumEnrouteAltitude.AltitudeIndication with values:

Noted: If there are multiple instances of AltitudeIndication, for safety reasons, the maximum value of the element AltitudeIndication.altitude among multiple instances shall be mapped to RouteSegment.minimumEnrouteAltitude.

  • Remove the AltitudeIndication
  • Copy the minumumEnrouteAltitude.AltitudeIndication.altitude into RouteSegment.minimumEnrouteAltitude (only copy the maximum altitude if more than one occurrence of AltitudeIndication)
  • Add an annotation.Note associated with the RouteSegment having:
    • translatedNote.LinguisticNote.note=”minumumEnrouteAltitude.AltitudeIndication.altitude: <altitude> <uom>, minumumEnrouteAltitude.cardinalDirection: <cardinalDirection>, minumumEnrouteAltitude.navigationEquipment: <navigationEquipment>, minumumEnrouteAltitude.direction: <direction>”.

Mapping example

Mapping example to be added...

(Note: for mapping test data see:

AIXM 5.2AIXM 5.1(.1)


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