Windsock

moxiepilot

moxiepilot

Well-Known Member
Anyone know how many knots it takes to begin to swing an 8 foot wind sock into the direction of the wind?

For example, the wind is light, lets sat under 5-6 kts. The wind sock at the east end of the field shows the wind from 270 the sock at the west end of the field shows 180.

In order to prevent the, "well, since the winds are light does it really matter?" question. Yes, I have an anal CFI for my CFI training and would just like to justify to myself that winds below about 3-4 kts don't really swing a sock so can make our perception of the wind correction correct for both of us.
 
I've never heard a figure to swing it, only to make it stand out. Lemme see if I can find it in the AIM.

edit: WTF?!? I can't find my FAR/AIM.
 
cessna_cptn said:
I think its 15 knots to put it straight out, and 8 knots for a 45 degree bend.
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yeah, that's about right for determining windspeed; however, I'm trying to figure out at how many knots the sock actually begins to swing into the wind to register the direction of the wind rather than to determine it's speed. Thanks for the reply though
 
moxiepilot said:
yeah, that's about right for determining windspeed; however, I'm trying to figure out at how many knots the sock actually begins to swing into the wind to register the direction of the wind rather than to determine it's speed. Thanks for the reply though
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Seriously, tell your CFI that it depends on if the wind sock caster poll is well lubed.
 
yeah, that's about right for determining windspeed; however, I'm trying to figure out at how many knots the sock actually begins to swing into the wind to register the direction of the wind rather than to determine it's speed. Thanks for the reply though
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[FONT=&quot]If the wind is so light I can’t tell what direction it’s coming from and the windsock has not swung…I consider it to be calm. Really anything under 5kts is generally considered calm anyway.[/FONT]
 
flyguy said:
For some reason 3 kts comes to mind but I don't know why. Sounds about right.
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I believe 3 knots or below is considered "Calm" to ATC. At 4 knots or above the controller will read "Wind XXX at 4, altimeter..."

Of course, I don't have any references either, just from personal experience that seems to be the way it works.

As for the windsock? I agree with Loblaw, it probably depends how well it's lubed.

Whenever your CFI tells you the secret answer, let us know.
 
jrh said:
I believe 3 knots or below is considered "Calm" to ATC. At 4 knots or above the controller will read "Wind XXX at 4, altimeter..."
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minor point, 4 knots and less is calm. Controllers can spit out the actual/estimated speed if they want.
 
Hmm...looks like I was a bit off with my previous post.

Advisory Circular 150/5345-27D, FAA Specifications for Wind Cone Assemblies says this on page 5, paragraph 3.5:

"Windsock Movement. The windsock must move freely about the vertical shaft it is attached to and when subjected to wind of 3 knots (5.6 km/hr or 3.5 mph) or more and indicate the true wind direction within +/- 5 degrees."

So there you have it...3 knots.

The 5 mph I mentioned above only applies to "supplemental wind cones," whatever that means.

http://www.aopa.org/members/files/ac/ac150-5345-27d.pdf
 
I was thinking calm is under 5kts only because the calm wind runways I see use that as the breaking point for use.
 
moxiepilot said:
Anyone know how many knots it takes to begin to swing an 8 foot wind sock into the direction of the wind?

For example, the wind is light, lets sat under 5-6 kts. The wind sock at the east end of the field shows the wind from 270 the sock at the west end of the field shows 180.

In order to prevent the, "well, since the winds are light does it really matter?" question. Yes, I have an anal CFI for my CFI training and would just like to justify to myself that winds below about 3-4 kts don't really swing a sock so can make our perception of the wind correction correct for both of us.
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Tell your CFI to get a life if he's asking that question. Seriously, how does that help you in any way, shape or form???? What flight school are you at? I've been wanting to do a discovery flight for fun...:bandit:

Sorry, it's a pet peeve of mine for instructors to go so far into minutia that they have no clue how to actually teach the art of flying (not saying yours is like that, it just sounds like it).
 
txpilot said:
Tell your CFI to get a life if he's asking that question. Seriously, how does that help you in any way, shape or form????
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I doubt the question was asked because it matters in day to day flying. It was probably asked in order to get moxie to dig deep into the books and find out just how much information is out there and how to get it. If you ask too easy of a question moxie could have looked it up in 5 minutes in the FAR/AIM and gotten the answer, yet not learned anything about how to research really tough topics.

I've been a flight instructor for almost a year now and I learned more about the scope of advisory circulars because of this. I don't think it's a wasted exercise at all.
 
I guess it depends on what he's training for, also. I was taking this as PVT training. If he's a COMM stud, or farther, I can see it, maybe. I've just seen way too many CFI's with the Napoleon syndrome and ask some stupid, irrelevant questions.:banghead:

Depending on the context, I partially retract my statement:)
 
maybe he's preparing him for that irritating student that will ask these types of questions and expect him to find an answer, beats me.
 
txpilot said:
I guess it depends on what he's training for, also. I was taking this as PVT training. If he's a COMM stud, or farther, I can see it, maybe.
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Haha...you're right, for PVT students that question would be ridiculous. I don't think he's at that level though. My understanding is that he's reaching the end of his initial CFI training. I gathered that from other posts of his I've seen, but he also mentioned it in his first post here:

moxiepilot said:
...Yes, I have an anal CFI for my CFI training...
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