I have to admit, I'm amazed at the nerve this thread has struck. Comments like "put your hand over their mouth", "give them medication", "sit in the back of the plane", PARENTS
DO SOMETHING... genuinely saddens me.
My children have flown w/ me since they were very little - not often - only when we were in the service and not for years afterwards - but when they did, I made every effort to make life easy for ME - as I expect most parents do: fly the redeye when you can - fewer people, more room to spread out - maybe they'll fall asleep; all the other "tricks" folks have described here - food, entertainment, familiar things - I've subscribed to. And sometimes in spite of everything, little Johnny gets possessed.
I suspect that the more outrageous comments are born of the bravado provided by anonymity. But I hope all of you know that none of us who travel with children embark with any intent to disregard your predictable and justifiable desire to endure little Johnny in a possessed state. I suspect if it seems that way, it's either a minority parent with no instincts at all of truly being a parent (in which case you won't be able to give them a character transplant), OR you just can't recognize the frustration they are suffering.
I call for compassion and an ability to accept with grace the trials life hands us sometimes