Is it Rude to ask Someone to Quiet a Child on a Plane?
A: If the child is an infant, try to be sympathetic. Intervening won’t help, but some earplugs might. When an older child is misbehaving (kicking the back of your seat, for example), then go ahead. Usually, talking directly to the parent—or even the child—will do the trick. If the problem persists, you should involve a flight attendant to keep the situation from escalating.
37: The percentage of passengers who would prefer to sit next to a smelly adult than a crying baby.
Source: Harris Interactive