I am afraid of heights, even when I am not afraid of falling. I dislike being on a high balcony even if I am ten feet away from the edge, with a trustworthy railing there. That's the way my body works - the fear is left over from more primitive times, before high places had windows and railings.
I've been complaining about this for years. I want a railing that will stop me from falling over the edge if I get into that situation, not one that will merely ensure I go over headfirst.