We flew about three weeks ago with a DS5 and DD2. We had her a seat and thought she would sit there; we also didn't want to drag the car seat with us since we were using ME, we didn't need it there. We were wrong. Our flight was a little over two hours each way. Our little girl was kinda of scared on the plane. Wanted to sit in her mommy's lap. The airline said since we bought her a seat, FAA said she had to sit in it during take off and landing at least. DD would have been much happier in the seat that she is accustomed to riding in. ME would have hauled our seat anyways, we wish we had took it. Just our thoughts.