# Wind at 5000 ft and wind at ground

#### secretapproach

##### New Member
Can any of you CFIs tell me what the rule of thumb is for determining the wind at ground level if I know the wind speed and direction at 5000 ft (or any other altitude). I remember that there is some trick to knowing it but it escapes me right now. If you have an online source that would be even better!

Thanks!

sa

Well, on takeoff I think you can assume like 45 or 90 degree shift to the right. So if you're at 5,000 and going down move the wind 45 or 90 (can't remember which .. leaning towards the 90 mark) to the left.

I'm sure I'll be corrected forthwith ...

I *remember* reading that it's more like 20* to the right on takeoff, so on landing you'd shift it 20* to the left: i.e. 300 @ 18 would theoretically become 280 @ 18 or slower due to ground friciton.

But terrain features, time of day, position of planets, etc. all have an effect on that so it comes down to: the wind is doing what it's doing.

I'm not a CFI (I just play one on TV), but I've never heard of such a rule of thumb. Seems like there are too many factors involved... I would either:

A) Listen to the ATIS, AWOS, look for a windsock, etc.

B) Look for smoke, etc.

C) Perform a wind drift circle.

Option C if I were about to do ground ref maneuvers.

Dave

[ QUOTE ]
I *remember* reading that it's more like 20* to the right on takeoff, so on landing you'd shift it 20* to the left: i.e. 300 @ 18 would theoretically become 280 @ 18 or slower due to ground friciton.

But terrain features, time of day, position of planets, etc. all have an effect on that so it comes down to: the wind is doing what it's doing.

[/ QUOTE ]I agree.

There is a general rule of thumb that winds move clockwise and increase in speed as you climb and do the reverse when you descend. Works pretty good in rural Kansas where there's nothing much changing the airflow. But add some hills and buildings and...

In reality it doesnt really matter (outside of planning for fuel) because you just need to do what ever it takes to make the airplane go where you want. ATIS wind is nice, but most of the time useless. You don't set up a crab for the reported "6 knots" or "22G35" you set up for what's happening where you are at that time.

Thanks for the responses!

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