Is it safe to fly if my child has a cold?

Yes: If your child is old enough to tell you if anything hurts and he does not have a fever with a mild illness there really should be no problem with flying in most cases. If there are worsening symptoms he should be evaluated before your flight.

Probably: As long as your child doesn't complain of ear pain or have a significant fever it will probably be ok. If your child has a predisposition to ear infections or flud in his/her ears then i would recommend you have the ears evaluated by your pediatrician or ENT prior to flying.