On Thursday, May 8, 2014 3:37:26 PM UTC+12, wrote:
Why do so many experienced thinking pilots enter spins from low altitude turns?

I want to know because I'm becoming more experienced and thoughtful with every flight.

My sincere sympathies to the friends and family of this pilot. John did a great job explaining the the answer to this question: Why do experienced pilots spin in low. Here is a link to his thoughts:

https://groups.google.com/forum/?fromgroups#!searchin/rec.aviation.soaring/john$20cochrane|sort:date/rec.aviation.soaring/ibhUAkQ6Z1s/8WoOYyZIlqEJ

Hi Bruno, and thanks for all the great videos.

I agree with what John says there. The primary one is that around steep hills adverse horizontal gusts are a much bigger danger than many people realise, and a bigger danger than sink.

I vary my speed a lot. When I'm pointing at the rocks, or low over them, I want to see 65-70 knots on the clock on a normal day. A sudden 20 knot gust up the tail isn't going to stall me. If it's windy then I'll use 80.

As soon as I'm pointing away from the ridge and suddenly have hundreds of feet under the nose I'm happy to drop it back to 50 or 55, and accelerate again as I turn back towards the hill.

You can see an example here, in a video a passenger shot back in 2009 on their iPhone 3GS (the new ones are MUCH better).

https://www.youtube.com/watch?v=IU8IDDBgwg0

Remember: it's not actually the gust from behind and loss of airspeed that makes you stall and spin -- it's only if/when YOU pull the stick back to try to stop the nose from dropping (or to tighten the turn). If you keep the stick in the same place it was before the gust then YOU CAN NOT STALL/SPIN. The nose will drop. You'll eventually speed up again. Nothing worse than that will happen provided there is nothing solid in front of you, even if the ASI is reading well below your 1 G stall speed.

The bigger mystery is why competent people stall and spin over flat land, on the notorious turn from base to final.

If it's windy then the gradient can explain it. The lower wingtip gets less windspeed, less lift. The upper wingtip gets more speed, more lift. You could get rolled a lot, rather than a spin as such. Still not healthy. Turning higher can keep you out of the gradient. Flying faster will keep everything flying and give you more control authority.

That's on turns into wind (for landing). With turns away from the wind (turning back after a PTT), the gradient helps you into the turn at the start, but helps right you as you complete it.

Not that I want to be landing downwind on a day with enough wind to have that kind of gradient!! Fortunately, on those days you should have plenty of height over the fence to do a proper circuit.