Question about judging xwind, gusts, etc.

[LongRoadBob]

After studying (aeronautics, airplane motor and instrument, some meteorology) and loved it on my first flight I was wondering something.... My instructor had me check the weather before the first flight, showing me how to log in and how to get the weather information.

The thing is I did a "narrrow" (20 nm on each side) trip and using two airports, where both are some distance from our non-ATC airport. Ours is unmanned and has no weather info other than a wind sock.

So, as far as I can tell there is no other weather information, temperature, and especially not wind speeds and gust information.

Is this something that a pilot just develops with experience, being able to judge crosswind, etc.? I did see in the textbook a kind of simplified "guide" with (in norwegian so...even though I am fluent I am on less certain ground with some adjectives that are rarely used show up) about at X knots trees lean a little at top, etc.

I'm not really asking a direct question, but anything about how you judge xwind, or wind, or guess at how much it will gust...or other methods one uses for judging on an unmanned airfield with no info other than wind sock?

Just any points or experiences? Maybe with focus on when crosswinds are at a level that for most small planes can be iffy (15-20 knots?) what that looks like judging from trees, wind sock (sticks straight out?)

For that matter, at what point is a wind sock useful for wind strength? I know it's main purpose is direction, but is there a wind that will make it straighten out and after that no longer any kind of indication?

Any pointers at all..

 

[azure]

For that matter, at what point is a wind sock useful for wind strength? I know it's main purpose is direction, but is there a wind that will make it straighten out and after that no longer any kind of indication?

I haven't seen this question asked recently so I thought I'd answer... if you want to delete the thread, let me know and I'll delete this post.

Wind socks (at least in the US) are rated for different wind strengths - some stand straight out at 15 kts, others at 20, and maybe there are other wind ratings as well. In short, I don't know any way to "read" wind strength (lower bound) from a sock without knowing its rating, e.g. by asking someone who knows.

Now this may be different in Norway - I'm just not sure.

 

[Vance Breese]

Most of the wind socks at the airports I fly into are 15kt wind socks. In other words they will be fully erect in a 15kt wind.

A little more wind can make a lot more challenge.

Often the wind near the ground will be different than the wind at even 1,000 feet above the ground because of the way ground objects affect wind.

A cross wind that works fine at one airport may be a challenge at a different airport so your flight instructor will help you develop limits and as you experience grows your limits may become less rigid.

Flags, dust, grass and trees can all help you to understand what the wind is doing.

You will need to find out if the nearby weather reported has any value at your field. Where I live the wind may be blowing in a completely different direction just a few miles from the airport.

When I am flying in an unfamiliar area I trust what the windsock says more than the weather at a nearby airport.

The aircraft I fly lands slowly so I try to touch down near a wind sock.

There are five windsocks at the airport I fly out of and they are often all blowing in different directions.

Good luck on your aviation adventure.

 

[coloradobluesky]

The windsock should tell you what runway to land on. You can tell if its gusty if you are getting knocked around on short final. There can be actual turbulence in the flare. Keep it straight with the rudder and pointed down the runway with the ailerons. The wind flag should tell you which way (coming from right or left) the crosswind is coming at you. Lean into that wind and feel the plane onto the pavement.

No matter how many times you bounce, keep it straight!

 

[Stewartb]

This past weekend the windsock at my cabin strip was turning in circles. The overall flow was easy to determine from trees and water but the very local winds were not consistent in velocity or direction as mechanical turbulence was in play. In that case carry a bit more speed like you were taught and aim a little further downfield than normal on final. I also prefer to be steeper in those conditions. Be prepared for the lift to diminish and increase in spite of what you do. Ballooning is better than dropping out of the sky but you may get a taste of both.

 

[coloradobluesky]

Quartering tailwind is the worst. Aileron on the side the wind is coming from will be pointed up and the tailwind will push that wing up, in the wrong direction. Its a problem with no perfect solution. Best to go around and come in the other way.

 

[Clark1961]

Quartering tailwind is the worst. Aileron on the side the wind is coming from will be pointed up and the tailwind will push that wing up, in the wrong direction. Its a problem with no perfect solution. Best to go around and come in the other way.

What? Smh.

 

[coloradobluesky]

Think about it. If there is a crosswind, either from in front or behind, the plane will have to crab to follow the runway. You get rid of that crab by pushing on the rudder and use the aileron to lean the plane into the wind. Standard crosswind technique.

If the wind is coming from behind to the left, the pilot leans the airplane into the crosswind, putting the left wing down and right wing up, keeping it straight to the runway with the rudders. Now as the airplane slows down and/or it gets a gust, that wind coming from behind to the left pushes against the left aileron, which is UP, the wind coming from behind at an angle. This raises the left wing, something you dont want in this situation. Its just aileron aerodynamics.

It works correctly if the wind is quartering from ahead and left. The aileron sticking up on the left side is pushed down by the wind coming in from in front of the wing. Which is what you want.

Hope that explains it.

 

[Clark1961]

Think about it. If there is a crosswind, either from in front or behind, the plane will have to crab to follow the runway. You get rid of that crab by pushing on the rudder and use the aileron to lean the plane into the wind. Standard crosswind technique.

If the wind is coming from behind to the left, the pilot leans the airplane into the crosswind, putting the left wing down and right wing up, keeping it straight to the runway with the rudders. Now as the airplane slows down and/or it gets a gust, that wind coming from behind to the left pushes against the left aileron, which is UP, the wind coming from behind at an angle. This raises the left wing, something you dont want in this situation. Its just aileron aerodynamics.

It works correctly if the wind is quartering from ahead and left. The aileron sticking up on the left side is pushed down by the wind coming in from in front of the wing. Which is what you want.

Hope that explains it.

still smh. if the wind is pushing on the aileron then the aircraft isn't flying. Remember that the airflow is from the front of the wing to the back of the wing if the aircraft is flying.

 

[James331]

Like it was said in the other thread, surface observations will tell you quite a bit, look outside, fly low

 

[coloradobluesky]

The plane is landing, part flying, part rollout. When the crosswind exceeds the forward speed of the aircraft the crosswind will take over. Even if it doesnt exceed it, it will reduce the downforce effect of the wind coming from the front when the two winds add together.

 

[LongRoadBob]

heh..I removed the apology for similar thread as one existing. The answers here have been great and REALLY helpful! Thanks!
I'm assuming though that though "most" wind socks are erect at 15 knots, it isn't quality controlled when they make the sock? It is just something that most often is correct and works?

I have noticed a few things since starting flying.
1) I notice I am turreting my head a lot more when I drive, and also keep looking for air traffic up (that last part may not be smart while driving...)
2) When outside, or just looking outside, I start looking for clues to wind direction and strength...smoke, papers on the ground, grass, trees.
3) Maybe got the idea somewhere here, when driving around outside of built-up areas, I have been noticing a lot more what the farm fields, open spaces, really look like and imagining how they might look smoother than they are from the air.

And one last thing I like a lot. My father was a terribly drivers ed teacher (too much critique, and yelling) but when we weren't actively doing that as a kid I remember him giving me driving tips. One was that "a good driver" slows down coming up to a stop or red light, to the point where when really good the passenger can hardly tell when the car has stopped completely. I think it is true within limits, but think he got that from taxiing. Also, he thought and told me a sign of a good driver is "parking" the speedometer to the speed you want to go and uphill or down, keeping it right on the money. I think too he is right (seen a lot of drivers speeding up, slowing down, maybe not unsafe, but makes them seem clueless as drivers) about that but also I think that also came from paying attention to airspeed, etc.

Thanks for the tips! Keep em coming!

 

[denverpilot]

Think about it. If there is a crosswind, either from in front or behind, the plane will have to crab to follow the runway. You get rid of that crab by pushing on the rudder and use the aileron to lean the plane into the wind. Standard crosswind technique.

If the wind is coming from behind to the left, the pilot leans the airplane into the crosswind, putting the left wing down and right wing up, keeping it straight to the runway with the rudders. Now as the airplane slows down and/or it gets a gust, that wind coming from behind to the left pushes against the left aileron, which is UP, the wind coming from behind at an angle. This raises the left wing, something you dont want in this situation. Its just aileron aerodynamics.

It works correctly if the wind is quartering from ahead and left. The aileron sticking up on the left side is pushed down by the wind coming in from in front of the wing. Which is what you want.

Hope that explains it.

Besides Clark's commentary about relative wind over the wing being the only thing the aileron is going to be "hit" by...

Let's say you take a gust that completely stalls the wing completely from behind so there's zero relative wind hitting the wing, before the aircraft can accelerate back to flying speed in the new airmass... You're a rock, and falling.

But besides that... Why would the aileron be UP anyway? Or deflected much at all? You're not adding bank after you've established the approach and stopped the lateral movement relative to the runway.

Once the bank angle for the crosswind correction is established in a crab, the aileron is neutral. As you transition to a slip for the landing, you'll need a LITTLE bit of aileron to counteract the cross controlled rudder, but you'll "run out of rudder" long before the aileron is all the way up, in most designs.

The aileron won't go all the way up until you're landed and rolled the controls hard over into the wind when landing into the wind. And that is exactly where you want them to taxi into the wind.

If you landed downwind, you're still moving well faster than the airmass at touchdown, so Clark's point again still applies, but on the downwind landing, you'll want to roll the aileron away from the wind at touchdown, not into it, which will put the other side aileron up and hold that wing down.

But the aileron won't "feel" any wind from behind it until you're well slow enough that you're not flying anymore, and you have time to reverse the controls as you pass from flying to taxiing when the wing is "feeling" zero forward or reverse wind and you're taxxiing at the same groundspeed as the tailwind component. If the tailwind component is say, 20 knots and you touched down indicating 55... You have to lose 30+ knots before the relative wind will hit the aileron from behind.

Sure, gusts, gusts you say. If they're so bad you're going from stall speed plus margin above stall speed that you're carrying down final for the gusty conditions, to the relative wind pushing on an aileron from behind, you'd need gusts from behind > than your final approach number -- for the wind to be " pushing" hard enough on the aileron from behind to apply any significant turning force to the aircraft.

I think you're trying to explain the whole wing changing its angle of attack as the gusts change the speed of the air mass it's flying through, away -- as some odd force exerted on an aileron.

Changes in lift are occurring across the entire wing in gusts. Nothing is pushing on the aileron from behind in forward flight.

If you had gusts that powerful from behind, you wouldn't be able to land it.

That'd be enough of a gust or shear (same thing in this example, or close enough for it) that you'd be reporting 60+ knot changes in indicated airspeed while coming down final in most of the aircraft folks fly here.

(Adjust accordingly for your normal approach speed +10 or whatever you like to add for gusty conditions.)

This "aileron being hit by gusts from behind" thing doesn't hold water until you're well below stall speed, taxiing.

 

[Vance Breese]

Wind socks are designed to be fully erect at some specific wind speed. It is 15kts at most of the airports where I fly.

 

[Clark1961]

Wind socks are designed to be fully erect at some specific wind speed. It is 15kts at most of the airports where I fly.

Windsocks in Wyoming have a logging chain added so they won't be standing straight out all the time. That was a joke but if you've spent any time there you'd understand.