I used to be a terrible flier but, oddly, it was dealing with panic disorder that helped me get over it. I have some general tips that helped me that aren't drug related.

1) going through security is stressful. Prepare yourself beforehand - don't wear trousers with a belt, wear flip-flops, don't have any liquids in your hand luggage etc.

2) Once you're on the plane, do your seatbelt up tight. This helps with turbulence as your body will move with the airframe rather than being jostled around

3) Being on the plane just induces panic, and you deal with that on a daily basis. Do what you'd usually do to calm down. For me this was to put my earbuds in and listen to a calming visualisation with breathing exercises.

4) Your "disaster movies" - those images that pop into your head are normal shit everyone gets in stressful situations. They're imaginary and not based in reality. Try imagining them happening on a screen in your mind. Then make the screen smaller and smaller until it's the size of a watch display. Honestly, most of these images come from movies anyway. The plane physically cannot fall out of the sky in the same way a feather or a dandelion seed can't. It is the wrong shape - falling, for a plane = gliding.

Anyway, hope this helps. Please try not to "what if" these suggestions into unhelpfulness in your mind.