Where is American Airlines' largest hub in the US?

This question tests how familiar you are with their airline and the extent to which you've prepared for the interview. Consider such questions an opportunity to showcase your work ethic by going above and beyond. Some cursory research will inform you their primary hub is out of Fort Worth Dallas airport. But the second biggest hub is out of Philadelphia, and they also list several other locations on their site. So share a bit more, going deeper with your answer and displaying that you already have a head start on your training, setting up their expectations that you would be an exemplary employee.