The Downwind Aspect
Didn't really see any mention of it above so thought I'd mention that in my view a steep downwind approach is a great way to end up settling into your own downwash.
My first exposure to it was in a UH-1B and I encountered it as I approached with a mild downwind for a low flyby inspection of a prospective LZ at the junction of an L-shaped gorge. It was only the latter perspective on the high terrain that made me aware that something was seriously wrong. Introducing lots of collective just accelerated that downward vector and induced a very distinctive sonorous beat in the Huey's blade-slap. As I'd probably slept through the lectures on retreating blade stall and VRS, I can only conclude that it was a 19 y.o.'s superior reflexes that made me shove the nose down and go for an accelerating disc. Or maybe the recovery was helped by an enforced turn away from the gorge walls.
It was very attention getting and adrenalizing and I've no doubt that if it had been at night or with NVG's, I'd not have picked up the cues early enough to have escaped. As I recall, the a/c was very light-weight (just me and 800lbs of gas, no winch).