S.H.
I have a Roundabout and have taken it on airplanes several times. It definitely fits in the seat. I also have a bag with a shoulder strap for carrying the seat through the airport, but it is very heavy. If you've seen the wheels that can make it into a stroller, I'd really recommend that, no matter the cost, because pushing a regular stroller, carrying a carry-on and the car seat, is a lot for 1 person! Good luck on your travels, hope this helps.