Taking autistic 3 year old on holiday with 11 hour flight?

My son is 3 and has been diagnosed with autism, he is non verbal, he doesn’t communicate at all, we went on holiday last year when he was only 2, he didn’t mind the flight and slept most of it, he runs off if not in a pram, the hotel we stayed in was all inclusive and had a kids splash pool which he really liked so he happily hung out there most of the time, but one of us had to be with him in that pool incase he ran off, my partner has suggested we go to America for 2 weeks and stay in a villa and visit the theme parks, my 3 year old would be in a pram for the theme parks, but I’m worried about the long flight and if he doesn’t like it I won’t be able to calm him down, he’s getting worse as time ones on and the diagnosis is very new to us, it was a bit of a shock I guess as Iv not come across autism before and I guess if I had then maybe I could have spotted it and prepared myself, but anyways has anyone took a young child on a long flight and holiday, I’m worried!