I think your 8 year old is like alot of us adults, we hear the news, we know what happened in new york and DC. Unfortunately fear is NOT rational. And percentages and odds do not eleviate those feelings.
I would contact your child's doctor. The first time we flew two years ago after quite a few years of driving, our than 11 year old was very "nervous" about this. I was able to get a prescription from his pediatrician. I was hoping i would not need to use this, but as we boarded the plane he started to have a panic attack. So i had to give him a pill, and while we waited for it to take effect, we distracted him will alot of silly talk and games both dad and i at the same time so he was constantly trying to keep up with our questions.. This was a very MILD prescription, it did not knock him out, or make him loopy, it was just enuf to take the intensity level down a notch or two.
Well thats all it took, he was fine on the way home and hasn't needed help to fly since (we have gone 3 times a year since then).
Good Luck
Deb
p.s. Mom still takes a "little" some thing to take the edge off so she can fly.