N.K.
For safety reasons, I always take a car seat on the plane for my son. So far we've taken a Snugrider infant car seat and stroller frame, for babies up to 20 pounds. Soon we will start using a stroller that's designed for Britax car seats called the gogo Kidz Travelmate, which leads me to believe that Britax will fit on planes. We have one of the smaller Britax seats, and it is FAA certified.