There is an example in here about walking a beam above a drop ceiling 2′ below and everything is fine, until the rigger gets a glance of the floor 80′ below him. Then he gets very tense. Nothing has changed, just what he can see. I know this feeling all too well. The only thing I can add is that personally I lose the sense of height when I’m more than about 150′ up or so. Any more I am never up this high simply because most buildings I’m in these days are only 60′ tall or so. And the majority of rigging I deal with is on mobile stages that are only 24′ tall or so, and we are not on top of the beams.
This is a long section simply bc it has a bunch of drawings. And they draw the rigger up, and a ground rigger down and so it takes up lots of paper space.
It gives an suggestion of trying to walk a railroad track and trying that before you try to walk a beam 100′ in the air. I thought this was an excellent self test.