Originally Posted by ricktoronto
Flagship: The chief one of a related group: the flagship of a newspaper chain; the flagship of a line of reference books.
Hence the one with 85% of the slots is the flagship.
Your conclusion doesn't follow: AA is not related to the other airlines that operate out of DFW. Based on your definition, AA could call DFW its flagship airport, but that does not make AA the flagship carrier out of DFW.