Lileks:
The Piccadilly was knocked down for the Marriott Marquis, which is really one hell of a hotel. I stayed there for a week; loved the rooms and the hotel and the location, but I absolutely hated the glass elevators. Practically had to huff a bag of laughing gas to get on the things.
It's a problem with Marriotts in general. The large atrium with the glass 'vators seems to be a trademark. I hate them. They don't seem to take into account the acrophobes among us.
I like flying in light planes and watching the scenery. It amazed me how I reacted to a glass elevator a few years back. By the time we reached the top, I was against the back wall.
Yes, there's a huge difference between flying and standing on a high structure, that non-acrophobes don't understand.
And it's a purely psychological issue. I trust nature, but I don't trust artifice, even though I'm an engineer, and rationally know that it has been designed to be safe. I can climb a mountain, but I'd never do a vertical rock climb with ropes.
I think it has to do with perspective. If your standing in a glass elevator, you're looking at the ground going away and you have no control. Climbing a mountain is easy because the ground is right there under your feet and you have control. Climbing with ropes there is little ground beneath you. I crossed the bridge behind the castle in Germany that inspired disney (Neuschwanstein (sp?)) and the bridge had gaps between the boards. That was really tough for some reason. Probably because the planks were not natural and I could see the gorge below me...no control.
What I can't stand is that sudden urge as you come to a ledge or precarious perch that feels almost like you are going to impulsively jump off. It is not a feeling of I'm going to fall as more of a feeling that you are going to suddenly lurch over the edge.
Knowing a bit more about anatomy now I understand that the flight or fight mechanisms are kicking in. I just keep reminding myself that these feelings are merely chemical precursors that I have no direct control over and that I should take a deep breathe and enjoy the view.
I have exactly the same response as Josh, the good thing is it wears off with familiarity, the bad is that the confidence is very localized to exactly the places you've grown somewhat comfortable with.
The real trouble is that it isn't just triggered by me, I can get really antsy and worried watching someone else in a similar place/situation. And for some locations my instinctual "safe zone" is several meters from the ledge.