Try to get your baby to take his bottle during take off and landing, even if it's just water/juice and not a feed. This has the same effect as us sucking a boiled sweet, it should alleviate his little ears popping. That's the main reason little ones scream all the way through a flight, it's uncomfortable and unpleasant and it really disturbs them so they're unsettled for ages.
Take plenty of dirty looks with you too, for all those grouchy gits who forget we were all squealing babies once :o)