We never really had a problem with my older two when they flew. (Oldest was 5 for her first flight - she colored the whole time; middle child was about 18 months and she slept most of the flight!) Haven't had any problems with them since.
But my youngest DD was 3 the first time she flew. Piece of cake! She slept the whole way there, and not only did she sleep the whole way back, she also slept through the restaurant that we stopped at after landing for dinner, and then slept until we pulled into the driveway - which was about an hour drive!!! Disney must have worn her out!!!!
However, on her second time flying, she was 5 yrs old and couldn't wait to be way up in the sky. She was even going to pass over her school so she could wave to all her classmates. Well, when the plane started to back up, she decided she didn't like that at all (she really wanted to get off the plane, and it had barely moved!!) When the plane revved up the engines and starting going fast down the runway for takeoff, my DD was screaming! She was so scared. She swore we were going to fall (she kept asking if there were any big drops - like on the rides). And once she started crying, about 7 or 8 other kids started crying! I kept reassuring her that everything was going to be fine and there were no big drops! She finally settled down and colored. I got a little nervous when it was almost time for landing, so we played a game of looking for the castle from the plane, and then guess when the plane touched the ground. It worked and she was fine. (I dreaded the flight back home!!! But she did pretty good - no screaming, although poor thing just had tears coming down her cheeks at first).
She's flown several times since then, and she'll usually color with her marker book. I always get her one of those clear markers that when you color on the page, it turns a color. That way, there's no mess. Thankfully, our flights are only about an hour and 20 minutes.
Good luck! Have a great trip! Allison and I are taking a quick trip to Disney in 24 more days - and she is so excited to be flying down! Can't wait!
