Possibly, this entirely depends on the child’s overall health and immune system. A 3-month-old baby is usually old enough to fight many pathogens as long as their immunity is strong. Nonetheless, some may still present with weak immune systems for several reasons, and they may often require additional time of up to even six months before they are ready for plane travel. But even so, serious precautions should be taken, and the child’s pediatrician also consulted extensively on the matter.