A former aviation security officer who lost his job after assisting in dragging a man from an overbooked United Airlines flight in an incident that drew global outrage is suing the airline.

James Long was one of several officers who forcibly removed 69-year-old Dr David Dao from the United Express Flight 3411 on 9 April last year after he refused to leave the flight.

Footage of the shocking incident captured by horrified passengers was shared globally, with the controversy resulting in the airline apologising and changing its policy on overbooked flights.

Mr Long, who was sacked from his job in August last year following a disciplinary investigation, has filed a lawsuit against the airline, the city, Chicago's Department of Aviation (CDA) and its commissioner.

He alleges the CDA did not provide adequate training on how to deal with the situation and claims that United should have been aware that calling security to remove a passenger would “require the use of physical force”.