Originally Posted by srockgibson

I don't know about AA and UA, but several of us DL Liletime members shared with Delta the original NW LIfetime offering materials. NW used to aggressively sell those LIfetime memberships when you entered the Top Flight Club (later renamed World Club). The option of using the club when flying any airline was a key feature in the sale. I don't know whether that was true with AA or UA.