You know that kid at the mall who's screaming her way through the department store at a full sprint? Chances are, she got her mom to make a stop at the candy store. A sugar high is rough no matter where you are, but in a car or on a plane, it's a relative disaster.
For your child's pre-travel and during-travel meals, minimize energy-inducing juice and carbohydrates (and for god's sake, withhold the caffeinated sugar-fest that is soda). Aim for sleepy-making, quieting foods like protein and milk. Both can have a calming effect that will increase the chances of beautiful silence.
Up next: While sugary food is a no-no, food in general can be a lifesaver.