Originally Posted by AmuDarya
Kudos to Ka -2b Pilot for raising the question that should first come to mind.
Highly localized downdrafts are far from an unknown phenomenon at coastal boundaries, as he says and can be accentuated by topographic features. There were at least two hills in the immediate vicinity of 200ft. With the tolerances required for the manoeuvre even localized 20/ft sec winds would erase the margin of safety implied by the visuals in 20 secs, i.e. the manoeuvre gets squashed to the ground.
Yet there is little discussion along this obvious first line of inquiry.
It is a valid point, but convection in the sea air tends to be less not more. Glider pilots know that once the sea air has come in it will be harder to stay up, and not necessarily because it's all sinking, more like just less active, as the air is cooler.
As for sink in the lee of a hill, 12 knots down would be more typical of wave rotor in the mountains. And this time the hill is to the north and the wind south-easterly