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TLOF [TLA]

TLOF [TLA]

Owned by Wolfgang Scheucher
Last updated: 2019 Aug 19 by POROSNICU Eduard

Purpose and Scope

These pages contain the coding guidelines for the minimum and conditional data items of the TLOF subject, which is defined in the PANS-AIM as follows:

Touchdown and lift-off area. An area on which a helicopter may touch down or lift off.

A TLOF may or may not be located within a FATO, which in AIXM is modelled as a Runway of type 'FATO'.  A TLOF may also be collocated with a helicopter stand. TLOFs may be located at airports, surface-level heliports, elevated heliports (located on a raised structure e.g. hospitals), helidecks (located offshore) or shipboard heliports (heliport located on a ship). For the 3 latter ones FATO and TLOF will be coincidental.

The figure1 below shows a TLOF within a FATO.

The next figure2 shows a TLOF outside the FATO and collocated with a helicopter stand:


It is also possible that a Runway designed for airplane operations also plays the FATO role, without being explicitly identified as a FATO. After using the Runway for the final approach, the helicopter executes an air taxi maneuver to the TLOF, for landing.

A TLOF may be of any shape – usually square or round.

AIP context

In an AIP, TLOF information may be published in the following sections:

  • AD 2.16 Helicopter landing area,
  • AD 3.2 Heliport geographical and administrative data,

  • AD 3.12 Heliport data.

AIXM Model Overview

The figure below shows the main AIXM 5 classes used for the touch down and lift off (TLOF) concept.

The TouchDownLiftOff class is used for defining a load bearing area on which a helicopter may touch down or lift-off.

A TLOF may be situated on a Runway (of type equal-to 'FATO') or directly at an AirportHeliport (i.e. the TLOF may form an integral part of the FATO or be situated apart).

A TLOF may be identified by its designator.

The extend of the TLOF may also be described ba the ElevatedSurface class. In addition, its dimension may be described by a length and a width.

A TLOF may have a centre point. In AIXM 5.1(.1), this is modelled with an association with role aimingPoint, using the ElevatedPoint class.

AIXM 5.1(.1) issue

The aiming point is not the same position as the centre point of a TLOF. According to ICAO Annex 14, Volume II,

The geographical coordinates of the geometric centre of the TLOF and/or of each threshold of the FATO (where appropriate) shall be measured and reported to the aeronautical information services authority

...

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.

The name of the relationship hasAimingPoint and the property TLOF.aimingPoint are not correct, as they were intended to model the centre of the TLOF, not the "aiming point".

A change proposal is discussed in the AIXM CCB, see issue AIXM-268

The surface material and strengths of a TLOF is modelled by using an association with the SurfaceCharacteristics class (see also Surface Characteristics [SCH]).

Coding Examples

See child topics.

Child Pages

References

1,2 Source: ICAO Annex 14 Update Workshop, HAI Heli-Expo 2015