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Old 10th July 2003 | 16:53
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OzExpat


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Joined: Jun 2000
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From: Cairns FNQ
Lightbulb

as the procedure is based on nil wind
Errm, I beg to differ. An omni-directional wind is considered for the design of the pattern, to establish the protection area. If statistical wind data is available it can be used, otherwise Pans Ops require 3h+47, which is to say, 3 times the height in thousands of feet plus 47. So, if the holding is at 6,000 feet, an onmi-directional wind velocity of ((3x6=18)+47) 65 knots!

The reason for a double or triple WCA is that, if you have an adverse wind during the turn to the O/B leg, the aircraft will be blown back toward the holding point (or fix). Thus, there is a need to ensure that there will be enough distance to allow a neat turn back to the I/B leg.

For the most part, the equipment available to the "jet guys" allows an accurate determination of W/V, which can then be appropriately allowed for. It's only the pilots who lack that sort of sophisticated gear who need to use one or other of the above methods.
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