I made a thread called “lancelots airplane ride”. Go to my profike, posts started, its recent. Sorry i dont know how to post a link to it. I flew with him in cabin last month.
Take your rabbit for a few short car rides to feel the motion. Food water before the flight. Flavor the water with a little apple juice or v-8 veggie juice if thats what it takes. Feed benebac for a week prior to the flight and a week after. I coiled a soft blanket around lancelot so if he lost his balance he would have a soft landing. Veggies during the flight.
I wrote a very detailed thread – check it out.