Add to which that we're animals designed for motion at about 2 miles per hour (3.21869 kph) in x and y. We are not designed to be looking at copters 100 yards (91.44 meters) away from us wondering whether we're about to hit those trees that are 100.3 yards (91.71432 meters) away from us.... But, at least, as copter pilots, we don't have to worry about the Boogy Man (British: Bogey Man) of pilots of full-sized aircraft: cumulus granitus. Andy.