Maybe talk to the airline and quiz them to help you make up your mind?

As far as I am aware, they are pretty well looked after. Is your DD fairly good around people she doesn't know? If so, then I would say she would probably be ok. You would be with her until she got on the plane and then her Dad would pick her up as soon as she gets off. I can imagine it wouldn't be an easy thing to do as a parent, but I do think she would be ok.