I was reading an old Flying the other day, specifically their "What I learned about flying from that....." The article was written by an Army Helo pilot who was demonstrating a setteling w/ power manuver. The article suggested that the lesson of the manuver was that you shouldent decend vertically more than a couple feet cause you can get trapped in a bubble of air thats decending an loose your lift. Then today I was watching Jurasiac Park, scene where everyones flying out to the island in the Augusta. The manuver into a steep sided box canyon and decend vertically several hundred feet to a pad. Got me wondering if this was movie magic or if there's a way to do that safely, or is it a special circimstance when you're boxed in or what?