Former officer James Long says he wasn't properly trained to deal with misbehaving passengers, and therefore shouldn't have been fired.
RELATED: A moment-by-moment timeline of United incident
Long was terminated after the notorious dragging incident last spring, when Doctor David Dao was forcibly removed from his seat on a United flight at O'hare Airport.
RAW VIDEO: UNITED PASSENGER DRAGGED OFF FLIGHT AT O'HARE
United passenger dragged off flight
Long is suing United Airlines and the city of Chicago for more than $150,000.
WATCH: UNITED CEO SENDS EMAIL TO EMPLOYEES
United CEO sends email to employees after passenger dragged