I have anxiety issues around traveling generally and flying is up there.
Can you identify what specifically is causing this reaction? For me it’s being confined and not being able to leave if I wanted to. That took me a while to figure out, and not knowing what it is that you’re feeling can manifest itself as anxiety symptoms.
The only thing that helps me is being in a good mental state generally. I make sure I’m well-rested, have eaten sensibly (no vindaloo the night before…), am not hungover, etc. If I’m already in a fragile state before getting near the plane, I’m going to have a bad time.
Related to that, I leave loads of time to get to the airport so I’m not stressed about being late.
Once on the plane, I put my earphones in and try to go to sleep immediately. The less time that I’m conscious, the better. If I can’t sleep, I need something easy to read. Nothing tense. Anything to pass the time.
It might be worth getting some beta blockers from the doctor.