D.M.
Sometimes they surprise you, so keep as calm as you can - I swear they can pick up on our anxiety!!! As far as the airplane goes, bring some books and toys - preferably favorites or new ones that you can give to him on the plane! The toughest thing at this age is getting them to stay in the seat - so distraction is good. He will likely get fussy at some point. Remember, that's ok this is all new to him, just remain calm and try to be a calming force for him. Make sure he's sucking on something during takeoff and landing for his ears (bottle, sippy, etc)
Take the rest of the time as it comes. If he needs you as he might since it's all new - be there for him, and give it a couple days of adjustment. I still think he'll surprise you!!! Enjoy