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This page contains the mapping for the following data items as defined in PANS-AIM, chapter 5.3.3.1.1

j) TLOF (designator, centre point, length, width, surface type);

These properties, which are considered as minimum for the AIP data set are mapped to the following main AIXM 5 features:

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PANS-AIMDescription (PANS-AIM)AIXM 5Definition (AIXM 5.1.1)Remarks
DesignatorThe full textual designator of TLOF//aixm:TouchDownLiftOff//aixm:designatorTouchDownLiftOff.designator

TouchDownLiftOff: A load bearing area on which a helicopter may touch down or lift-off.

designator: The designator of the touch down and lift-off area.


Centre point - PositionGeographical location of TLOF threshold point

//aixm:TouchDownLiftOff//aixm:aimingPoint/aixm:ElevatedPoint

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//aixm:TouchDownLiftOff//aixm:aimingPoint/aixm:ElevatedPoint/aixm:horizontalAccuracygeometric centre

TouchDownLiftOff.aimingPoint.ElevatedPoint

and

TouchDownLiftOff.aimingPoint.ElevatedPoint.horizontalAccuracy

aimingPoint: Aiming point for the TouchDownLiftOff zone.

horizontalAccuracy: The difference between the recorded horizontal coordinates of a point and its true position referenced to the same geodetic datum expressed as a circular error at 95 percent probability.

Warning
titleAIXM 5.1(.1) Issue_021_TLOF_aimingPoint

In AIXM only the aiming point of a TLOF can be coded. The aiming point is not the same position as the centre point of a TLOF.

According to ICAO Annex 14, Volume II,

An aiming point marking should be provided at a heliport where it is necessary for a pilot to make an approach to a particular point before proceeding to the TLOF.

The aiming point marking shall be located within the FATO.

Currently in AIXM it is not possible to define two different points for a TLOF.

Workaround for AIXM 5.1(.1):

  • In case only the centre point location shall be encoded use aimingPoint.
  • In case both locations shall be encoded use aimingPint for the aiming point and code the centre point location as Note.

Status AIXM 5.1: See CCB AIXM-268

Info
titleAIXM 5.2 Improvements

A change proposal (AIXM-422) for the next AIXM 5.2 version has been approved by the AIXM Change Control Board, in which the association between TouchDownLiftOff and ElevatedPoint is renamed to indicate that it identifies the TLOF centrepoint, not the ‘aiming point’. In addition, the association between TouchDownLiftOff and Runway is renamed to indicate that the runway is used as FATO, even in the situation when the TLOF is not physically located on the Runway.

The coding guidelines provided here are aligned with forward/backward conversion rules contained in the AIXM-422 Change Proposal.

Centre point - ElevationElevation of the TLOF threshold

//aixm:TouchDownLiftOff//aixm:aimingPoint/aixm:ElevatedPoint/aixm:elevation

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//aixm:TouchDownLiftOff//aixm:aimingPoint/aixm:ElevatedPoint/aixm:verticalAccuracy		The "verticalAccurracy" encoded refers to both the "elevation" and the "geoidUndulation"geometric centre

TouchDownLiftOff.aimingPoint.ElevatedPoint.elevation

and

TouchDownLiftOff.aimingPoint.ElevatedPoint.verticalAccuracy

elevation: The vertical distance of the point measured from Mean Sea Level (MSL).

verticalAccuracy: The difference between the recorded elevation of a point and its true elevation referenced to the same vertical datum expressed as a linear error at 95 percent probability.


Centre point - Geoid undulationWGS-84 Geoid undulation at TLOF geometric centre point position

//aixm:TouchDownLiftOff//aixm:aimingPoint/aixm:ElevatedPoint/aixm:geoidUndulation

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//aixm:TouchDownLiftOff//aixm:aimingPoint/aixm:ElevatedPoint/aixm:verticalAccuracy		The "verticalAccurracy" encoded refers to both the "elevation" and the "geoidUndulation"

TouchDownLiftOff.aimingPoint.ElevatedPoint.geoidUndulation

and

TouchDownLiftOff.aimingPoint.ElevatedPoint.horizontalAccuracy

geoidUndulation: The distance of the geoid above (positive) or below (negative) the mathematical reference ellipsoid at the location of the point.
Info
titleInfo for accuracy

In AIXM 5 the verticalAccuracy refers to both the elevation and the geoidUndulation.

Hence, if the verticalAccuracy is coded for the elevation but the accuracy for the Geoid undulation is not known, this should be put into a corresponding Note.

LengthThe longitudinal extent of TLOF//aixm:TouchDownLiftOff//aixm:length

TouchDownLiftOff.length,

and

TouchDownLiftOff.annotation.Note.propertyNamevalue equal-to 'length'


length: The value of the physical length of the touchdown and lift-off area.
AIXM 5 does not provide a "lengthAccuracy" attribute for the "TLOF" feature.
Warning
titleAIXM 5.1(.1) issue
_022_TLOF_length

PANS-AIM defines an accuracy for the TLOF length. AIXM 5.1.1 does not have a dedicated attribute for that purpose.

Workaround for AXM 5.1(.1): A Note may be used.

Status: see CCB AIXM-269

WidthThe transversal extent of TLOF//aixm:TouchDownLiftOff//aixm:width

TouchDownLiftOff.width,

and

TouchDownLiftOff.annotation.Note.propertyNamevalue equal-to 'width'


width: The value of the physical width of the touchdown and lift-off area.
AIXM 5 does not provide a "widthAccuracy" attribute for the "TLOF" feature.
Warning
titleAIXM 5.1(.1) issue
_023_TLOF_width

PANS-AIM defines an accuracy for the TLOF width. AIXM 5.1.1 does not have a dedicated attribute for that purpose.

Workaround for AXM 5.1(.1): A Note may be used.

Status: see CCB AIXM-269

Surface typeThe surface type of TLOF//aixm:TouchDownLiftOff//aixm:surfaceProperties/aixm:SurfaceCharacteristics/aixm:compositionTouchDownLiftOff.surfaceProperties.SurfaceCharacteristics.composition

surfaceProperties: Surface characteristics of the runway.

composition: The type of the predominant material of which a surface of the movement area is composed.