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Gusting wind and Takeoff Charts

  • Flyingpom
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Flyingpom created the topic: Gusting wind and Takeoff Charts

There is a question in the cyber exams that looks requires me to use a Gusting wind.

"You arrive overhead Wlycheproof . wind is 260/20 G25. CW limit for each is 20Kts"

I used the mean wind only ( i.e 260/20 ) in the calc but was incorrect.

In terms of using wind for calculating landing or takeoff performance charts can you explain how I use the Gust Factor e.g

1. If i have a wind of 220/10 G 25 and I am using this to calculate a landing distance to I use just the 10kts or do I average the amount between the mean wind and the gust factor??

So far I have been ignoring the gust factor which seems fine if you have a headwind ( as you take the worst case i.e less HW ) but in the case of a cross wind if I take just the mean wind then I could exceed the CW limit ( in this case for echo )
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bobtait replied the topic: Re: Gusting wind and Takeoff Charts

You should always take the worst case. For a crosswind situation, you should really get both the headwind and crosswind component. Use the maximum gust value when considering the crosswind because it is possible that that may happen just as you are landing. If that makes the cross wind component go above the maximum allowable cross wind, then you will need to use another runway or carry an alternate. Use the lower value when you are considering the headwind component for the same reason.

The lower value is actually the Met Man's average of wind strength. You will never have to take an average between the lower value and the wind gust value.
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Marko replied the topic: Re: Gusting wind and Takeoff Charts

Hi Bob if the question is asking for takeoff weight and it gives a variable wind of say 3 kts Would you then use the worst case and call it a three knot tailwind
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  • John.Heddles
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John.Heddles replied the topic: Gusting wind and Takeoff Charts

Bob's earlier post sums up the strategy - be conservative so, yes, go with a tailwind.

Probably safer and certainly easier to argue at the enquiry.

Engineering specialist in aircraft performance and weight control.
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Marko replied the topic: Gusting wind and Takeoff Charts

As long as the person who writes the exam questions sits on the board of enquiry I’ll be ok then lol
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John.Heddles replied the topic: Gusting wind and Takeoff Charts

Good thinking, there, 99. :laugh:

Engineering specialist in aircraft performance and weight control.
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