When I first went on a plane I was terrified (especially the take off and landing), over the years I gradually improved although I can't say I enjoy it. What I find works for me is once I am settled in my seat, I close my eyes and do some deep breathing exercises and then imagine myself in my happy place (in my case it is a favourite holiday destination), anywhere you love to be - a beach, garden etc. Concentrate on that place whilst breathing deeply and slowly. I find this calms me until the take off or landing is over. During the flight I sometimes listen to an audio book which takes my mind off the flying.