I just completed a ow RTW trip in First class and to my dismay the only airline that would not allow me to fly in First Class was AA. I flew LHR-HKG on BA in First and HKG-LAX on Cathay in First. Both experiences were wonderful. And then I had to deal with an aggressive AA agent in LAX who insisted that I am only allowed to fly in business class on my LAX-JFK flight. She explained that on a 3 class service flight my ticket "allows' me to fly only business. How strange, my BA and CX flights were 3 class, and the service and comfort of their first class far exceeds AA. So why is AA allowed to refuse me first class on a First Class oneworld RTW ticket? Can someone please explain.