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The diagram below shows the AIXM classes, including the relevant data types, needed to encode that information:
TLOF designator
TLOF Centre Point (aimingPoint)
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TLOF designator
The TouchDownLiftOff.designator attribute represents the textual designator of the TLOF, used to distinguish physical TLOFs at an Aerodrome/Heliport that has more than one. The attribute value should reflect the local convention for physical TLOF naming at the Aerodrome/Heliport.
Example TLOF designator values could be: HELIPAD-A, HELIPAD-B; TLOF1, TLOF2; etc.
If there is just one TLOF , the Designator can be just "TLOF".
TLOF Centre Point (aimingPoint)
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In AIXM only the aiming point of a TLOF can be coded. Is the aiming point the same as the centre point of a TLOF? AccordingICAO Annex 14, Volume II,
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This definintions give the impression that the aimig point is not the centre point of the TLOF. Currently in AIXM it is not possible to define the two different points for a TLOF. Anyhow, it seems that the relationship hasAimingPoint and the property TLOF.aimingPoint is not correct. It should be rather hasCentrePoint and TLOF.centrePoint. Also, an aiming point may be idenpendent form a TLOF na d may also be marked and lighted. It seem that currently aiming point is not covered by AIXM 5. The workaround is to code that information in a Note. |
A workaround is to code the centre point of the TLOF using the ElevatedPoint class linked by the hasAimingPoint relationship.
In case an aming point and a centre point shall be coded for the TLOF, the actual aiming point has to be coded as Note.
TLOF Dimension (lenght & width)
Surface
The surface specification of a runway is related to the complete runway as a physical element and not related to the different runway directionsThe TLOF dimension attributes are used to describe the physical dimension of a TLOF.
The TouchDownLifftOff.length ist he declared longitudinal extent of the TLOF.
The TouchDownLifftOff.width is the declared transversal extent of the TLOF.
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| For both attributes a dedicated attribute to provide accuracy is missing |
As a workaround the accuracy value for the length and width may be encodes as note for the correpsonding property.
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| How shall a circle shape be coded? Diameter as length and width? Releation to Surface class missing? |
Surface
For the TLOF PANS-AIM requires to provide the surface type.
In AIXM 5 the SurfaceCharacteristic.composition attribute is used to code the surface type, e.g. asphalt, concrete, grass, etc.
The SurfaceCharacteristic class groups together the more attributes that model the characteristics of an airport surface, such as strength, material, etc.
For detailed information about the surface characteristic attributes & corresponding rules please refer to topic Surface Characteristic [SCH].
Coding Rules for Basic Data for
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TLOF
Coding Examples
TBD in the scope of the DONLON AIXM AIP dat set.