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I was out in the School Tecnam on late Monday morning for a bit over an hour from Lethbridge and on returning while entering circuit I noticed the wind had picked up a bit but was still Nth West where it was when I'd left.

 

Probably about ten kts with gusts so a bit of cross wind from the right on rwy 28. This is fine but you have to expect a bit of turbulence on final as you cross the tree line at the highway and also just before touch down from the hangers on the right.

 

What made this interesting was just as I was about to come over the fence having already hit some of the expected rough air there was this sudden feel of a big drop in air speed. Now I'd checked only a second before as I crossed the road 60kts, a full flap approach and then this nothingness feel.

 

Even before I could react with throttle as I glanced at the ASI it was wildly swinging up from below 60kts to 70kts and back to 60 again where it was originally, everything then continued on as normal with a right wing low touch down and a normal roll out. I had cockpit video and so I reviewed that few seconds, unfortunately with the turbulence tossing me around a little my head got in the way of the ASI and I didn't see how low it actually went but the wild swing back up was very evident.

 

Not one I'd felt before but then I'm only a low hours pilot, have others experienced this sort of thing?

 

Nico.

 

 

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Sorry its taken a bit to get back to this, been a bit busy.

 

This is a short video of a recent approach where I had a large air speed variation in turbulence on final. An uneasy feeling when your airspeed suddenly drops but fortunately returns as quickly as it dropped off. I think it was just a result of the turbulence from the tree line as I could see no other real reason for it but have a look anyway there is slow motion at the end to see if there was anything unusual and also because my fat head was bobbing back and forth due to the rough air, but as noted I couldn't see anything.

 

Thanks for looking.

 

 

 

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Looks like mechanical turbulence to me from the tree line. We get that over approaches on RWY18 at Penfield. Out of Riddells Creek same sort of thing on final approach RWY20. Just have to power through it and make sure there's enough speed so wings don't stall.

 

 

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Could have also been a bit of wind shear.

 

Years ago, coming into Moorabbin in a 152, I was coming in to 35L which had a bit of crosswind from the left. As I was just about to cross the threshold, I could feel the wind just die away and the aircraft start to drop. Corrected quickly with a bit of power and nose down and all was good. Instructor commented after that the buildings on the left side of the airport acted as a wind break reducing the wind strength.

 

Could be the same with that tree line along the highway.

 

 

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The country there looks quite open. It could have been a willy-willy. I was sitting in the hangar at Watts Bridge the other day and it was fairly still wind-wise. All of a sudden, I heard this rushing type sound building up and then this strong wind coming over the hangar from the rear. It took about 20 seconds to pass over the hangar and then all was still again. I think that was a willy-willy too, but we don't get a lot of them at Watts Bridge (that I'm aware of).

 

 

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Hi

 

Yah willy-willy or a rotating thermal if you like. I have encounter them at YLED and YBLT if you drive into one edge or the other you will either get a massive IAS increase with much lift, not bad that one, but the opposite is you fly into a hole and drop or stall. On variable wind or turbulent days I keep the approach seed up a bit.

 

Cheers David

 

 

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Thanks for the input guys, yes the Willy Willy was something that crossed my mind and also I have struck a day there where thermals were quite something and just trying to get down to circuit Highton was a battle, a little more wing area and I could have climbed out at idle :-)

 

 

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  • 2 weeks later...
  • 4 weeks later...
Sorry its taken a bit to get back to this, been a bit busy.This is a short video of a recent approach where I had a large air speed variation in turbulence on final. An uneasy feeling when your airspeed suddenly drops but fortunately returns as quickly as it dropped off. I think it was just a result of the turbulence from the tree line as I could see no other real reason for it but have a look anyway there is slow motion at the end to see if there was anything unusual and also because my fat head was bobbing back and forth due to the rough air, but as noted I couldn't see anything.

Thanks for looking.

 

It's a textbook landing. You did an excellent job, with the amount of cross wind and the last minute turbulence 107_score_010.gif.2fa64cd6c3a0f3d769ce8a3c21d3ff90.gif

 

 

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  • 2 months later...
Could have also been a bit of wind shear.Years ago, coming into Moorabbin in a 152, I was coming in to 35L which had a bit of crosswind from the left. As I was just about to cross the threshold, I could feel the wind just die away and the aircraft start to drop. Corrected quickly with a bit of power and nose down and all was good. Instructor commented after that the buildings on the left side of the airport acted as a wind break reducing the wind strength.

Could be the same with that tree line along the highway.

I know that this is an old post, haven't checked the thread for a while. re: YMMB, I had a similar situation on Rwy 35 (can't remember R or L, it was 40 years ago, but as I was doing a full stop after a bit of Xcountry, it was most likely 35L). I was in a Musketeer, and had my uncle, brother and brother-in-law on board. As we crossed the road on short final, the bottom dropped out of the world. I hit full power and held it low to build speed, and made a second approach and landing. Had 3 white faces with me when I landed.

 

 

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The tree line and the hangars sometimes cause mechanical turbulence on that approach at Lethbridge when the wind is from the right. Anytime there's a possibility of it happening use a powered approach and come in a little faster. If your speed drops off don't be afraid to use quite a bit of power to keep a safe airspeed. If you don't stabilise to your satisfaction go around. As your experience grows with these things you will make these adjustments and go round less . Low wing loading planes respond the most and are quite hard to manage as the wind strength grows, even when on the ground. Nev

 

 

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Carbon monoxide detector

Thanks Ian, yes that's exactly what it is.

We had some exhaust smells in the cockpit which I'd mentioned to David and he fitted the detector.

 

We found the exhaust problem a little later and had it repaired.

 

 

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