I have flown for business a lot (a lot) and maybe I have been lucky maybe I have been oblivious but I have NEVER encountered a loud/crying baby/child whose behavior lasted more than a few minutes. Ignore the dirty looks, bring the snacks etc as recommended earlier, and you'll be fine. Simply having posted looking for advice on this matter probably indicates that you are good conscientious parent/s and will know how to handle whatever comes up. Safe travels!
"True freedom means being conscious and aware enough to choose what you pay attention to and to choose how you construct meaning from experience.” ~David Foster Wallace