Flying is completely different.
Evenin' folks... I just flew in from San Francisco, and boy... are my arms tired... -rimshot-
Howdy all. [sip]
Flying is different because airplanes have floors under them, and the windows are too small to get the sensation of falling out of them.
I have a certain yet controllable acrophobic reaction to heights. I write it off as a sincere respect for gravity and all it implies. But I have a very difficult time getting close to edges of cliffs or peering over really long drops.
One of the hardest things I ever did was that bungee jumping thing some years ago off a bridge up in the mountains. Eric, my bud that I went with... was also into skydiving... which I'm not. He said that the bungee jump was magnitudes more terrifying than skydiving. When you're skydiving the ground is a long, long, long way away. When you're bungee jumping the rocks that you're going to bash your head against are RIGHT THERE and you can SEE THEM.
Its funny, but while the bungee jump was terrifying beforehand, once my toes finally left the bridge and I started falling... the sensation of fear *completely* disappeared. It's like there's a mechanism in the brain that clicked on a said "Well... nothing we can do about this now... may as well enjoy the ride... " :-)