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AIXM Model Overview


An entity grouping together the attributes that model characteristics of an airport surface (e.g. Runway or TLOF), such as strength, material, etc.

The composition attribute is used to code the type of the predominant material of which a surface of the movement area is composed.

The preparation technique(s) applied to a surface composition are coded by the preparation attribute.

The quality of the surface of an airport surface will be coded with the surfaceCondition attribute.

Coding guidelines


Pavement Classification Number (PCN)

The Pavement Classification Number (PCN) is composed by 5 attributes:

  • classPCN
    The bearing strength of a pavement for unrestricted operations.
  • pavementTypePCN
    The pavement behaviour (rigid or flexible) used for determining the Pavement Classification Number (PCN).
  • pavementSubgradePCN
    An indication of the pavement subgrade strength related to the Pavement Classification Number (PCN).
  • maxTyrePressurePCN
    The maximum allowable tire pressure category related to the Pavement Classification Number (PCN), as a category.
  • evaluationMethodPCN
    The method used to rate a runway pavement.

The figure below gives an example of a PCN specification:

If the bearing strength of a rigid pavement, resting on a medium strength subgrade, has been assessed by technical evaluation to be PCN 80 and there is no tire pressure limitation, then the reported information would be as follows:


Load Classification Number (LCN)

The classLCN is used to code the value, which denotes the peak bearing moment the surface can handle repeatedly without shortening its service life.

Single Isolated Wheel Load (SIWL)

Two attributes are used to describe the Single Isolated Wheel Load (SIWL).

The weightSIWL attribute represents the maximum calculated load on each tire of a landing gear assembly that a movement area surface can support.

The tyrePressureSIWL attribute represents the maximum aircraft tire pressure that a movement area surface can support.

All Up Weight (AUW)

The weightAUW attribute represents the maximum total value of the weight of an aircraft that a movement area surface may support, regardless of the landing gear configuration of the aircraft.

Coding Rules for Surface Characteristic


IdentifierData Encoding RuleJustificationData Verification Rule (UID)Remarks
SCH-101If classPCN is specified, then pavementTypePCN, pavementSubgradePCN, maxTirePressurePCNevaluationMethodPCN must be specified.ICAO Annex 14Draft rule 97DB0

SCH-102As a plausibility rule, the value of classPCN should be lower than 200.ICAO Annex 14Draft rule 979C8

SCH-103As a plausibility rule, the value of classLCN should be lower than 200.ICAO Annex 14

Draft Rule 98968


SCH-104If weightSIWL is specified, then tyrePressureSIWL must be specified.ICAO Annex 14draft rule 99138

Coding Examples


See topics Runway and TLOF.

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