The first time I ever cliff-launched a hang-glider I discovered another visual trick - with a bit of wind in my eyes I flared to land and found that the ground was missing. Looking down I discovered that I couldn't tell whether the surface was to be pebbles or boulders. It was a long wait - albeit probably not more than a second or two - before my boots met the ground. Luckily with a wing loading of a pound per square foot you can get away with a lot...