i had an ash of reasonable sizelate last year in a conservation site. it had to be climbed but everything was a straight drop, tree was in crap cond. was very windy but in gusts so cutting when gusts stopped, anyway, got to the all important final cut, the top, about 15', 6" dia, little directional gob to take it round and onto the path. top was leaning away from me about 50 degrees. waited for gust to stop, put in back cut and the wind gusted again just as i was pulling the saw out. i ducked a little and watched the whole top go straight over me. i leaned back and watched it sail about 40' away and land in some bushes. quite amusing but lucky it didnt catch me.
also the first tree i topped out after leaving college was an ash. had it all roped up to drop the top. put the back cut in just as a gust came . the top dropped over the top of me and a peg caught my harness, the whole top about 15' hanging on me harness ropes and all. knocked me off the spikes and crapped me sell just about. managed to free the top from harness but gave me a fight. now i put tug lines on tops, learned the hard way. bruised ego out of college tho!