I'm the same way when I fly. If I know I'm flying say a month prior I'm a nervous wreck for the entire month. I flew 6-7 times last year. But once I'm up I'm fine, hit bad turbulence and I white knuckle it.
Damn... I fly every couple of weeks. If I had some kind of anxiety, I'd be in trouble.
Was flying with a friend of mine a couple of months ago and she was a complete mess, during take off and landing she would clinch my arm with a death grip.
I feel for anyone who has this fear in any state.
She probably suffered from some sort of agoraphobia.