I recently flew SW and took one of my FWs as carry-on and it worked just fine. A little heavy for me to carry the mile and a half at the Nashville airport; the only complaint came from my GD who was there to meet me on my arrival back home--she said "why did you hand carry this heavy thing, Grannie? You could have checked it, you know." I have also done what some have suggested here; gone to Austin and bought a yard sale machine while I was there--never more than $15, and that is more than you would pay for excess baggage, isn't it? Plus, going into the belly of that plane, I know they "throw" them, and don't care if they fall off the rolling track into the plane.....my suggestion, have your sister check yard sales now if she can and call you when she finds one you might like, then repay her when you get there.