What a sensitive nerve I've hit on approaching the subject. It's the first time I've thought about Deepbuffet's theory of the fear of falling. This makes perfect sense. The feeling of looking over the edge of a cliff lying flat on the top isn't the same as going over it strapped to a rope. The feeling of security being strapped on to "something" overwhelmes the fright of heights.
So here's one: Do you ever think of the dope and fabric and few rivets and bolts holding the Cubs, Citabrias and Pitts together?
And another thing, all kinds of phobias interest me. Fear of flying isn't related to fear of heights - but when flying low with my wife for one of the first times, she told me that she found it uncomfortable. I didn't notice, but understood. I had a fear of heights until age 17 when working at a construction site, where I had to go 6 stories on outside platforms. Cured me for good.