Originally Posted by
willoL
My kids are almost grown now, but I *always* booked a separate seat for each one, and I *always* used a child safety seat in flight for the same reason I do in a car: my child's safety. If you can afford a third seat, booking it will be safest for your baby and IMHO make a flight less stressful, too. My kids were familiar with--and comfortable in--their usual seat from the car at home, and I knew I had a clean, safe place to set him down when I needed my hands free.
My mother made one flight with my brother as a lap child, and for every flight after that for him (and for me) we had our own seats and they brought our car seats. For actual flying comfort it was easier for all of us to be in our car seats.