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p25 - Trapezoidal gates

Proposal from

José Luis Esteban, Spain.

Proposal title

Trapezoidal gates

Existing text


New text

Annex 6. Insert 6.3.6:

At the discretion of the Director, a standard hidden gate may be extended to half its width again. When the standard gate is crossed, it scores 100% of the nominal gate value as usual. When the gate is crossed at an intermediate position between the gate width and the limit of the extension, the score decreases linearly as the crossing position approaches the extension’s limit.

Current points 6.3.6 to 6.3.8 need to be renumbered.


Tasks like Precision Navigation or Navigation with Unknown Legs are based on gate scores. In the case of a 200 m gate radius (400 m wide) a pilot flying 201 m away from the central point loses all his score in the gate. Losing all the score by 1 m is always disappointing for the pilots and makes the scores rather random. To mitigate this randomness, a large amount of gates must be defined, analysed and scored.

As an alternative, a gate may lose its value gradually. For example, when gate radius is 200 m (400 m wide) the zero-value radius may be 300 m and the gate value would decrease gradually between 200 and 300 m. A pilot crossing 201 m away from the central point would score 99% of the gate value, 50% at 250 m, 1% at 299 m and zero when the distance is larger than 300m.

This is not mandatory but an option for the director. In fact, current gate scoring is only a particular case of the proposed system, in which the gate width and the zero-value width are the same.

Added by José Luis Esteban Last edited by Richard Meredith-Hardy on 27 Oct, 2011 16:37. Quick links: or p25 - Trapezoidal gates
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