I also fly a lot with a roundabout, which is a great carseat. I have found it is easier to unbuckle from airplane seats if you twist the plate side of the belt half a turn, so the plate is upside-down relative to how you would wear it. That way, you can unbuckle the car seat by slipping your hand into the back of the carseat and just flipping the plate (toward the airplane seatback), without it getting jammed on the back of the carseat.