I think Cathay Pacific has an "entire Asian network" that far surpasses UA and you get points/miles on AA too.

I didn't answer your question though as to how AA is the largest. I don't know how they come up with it....if it's a combination of flights/employees/aircraft...I have no idea but there must be some general concensus as AA is regularly reported as the largest airline in the world. UA used to have that distinction before AA acquired TWA.

[This message has been edited by LLZ (edited 01-01-2003).]