I’ve done long haul journeys a couple of times….
Biggest tip was to have a selection of little toys / games etc with you… just small stuff that she hasn’t seen before….. that way the novelty keeps her going for a while…. and when you need a distraction, just pull out something new.
Then, make sure that when the plane is taking off or landing that she is drinking something… or sucking a sweet or something… because the jaw action helps release her ears… thereby reducing the pain.
And lastly…. I could get shot down by a number of folk on this one, and I’m not one to advocate it normally… but calpol / dozol or something similar can help to relax her… especially if on an overnight journey… and when she is relaxed, you will be too. Just have a chat with your pharmacist…. he should be able to recommend something to take the edge off the "off the wall" feeling!
Have fun! and enjoy your trip! 😉