I found relaxation tapes and a hypnosis tape helped me. I still don't like it much but I am much better. If you look in any store selling music they should have some somewhere, I can't remember the ones I had, but there are several about.
I am also clostrophobic so had double fears to cope with and now travel as far Canada, Australia, far East and we are planning a round the world trip now, so you can over come it. Try the tapes or CDs, listen to the hypnosis one now every day as often as you can and the relaxation one in between and take it on the plane with you. It does work but you have to think possitive.
Good luck and enjoy your trip.