Well, I haven't gone yet... I am planning to bring her carseat just in case there is an extra seat and she can sit in it...otherwise I have to just hold her in my arms. I'm guessing it is because even when adults are free to get up and move, you still have to have your seat belt on while sitting, and perhaps the front carrier would interfere with the seat belt?? I'm not quite sure. But you can use the carrier to get the baby on and off the plane.