CHICAGO (CBSDFW.COM/AP) — An aviation security officer fired after forcibly dragging a passenger from a plane last year has filed a lawsuit against United Airlines and the city of Chicago.

James Long was one of the officers called to a plane in April 2017 after Dr. David Dao refused to give up his seat. Video taken by other passengers show Long dragging a bloodied Dao from the plane. Long was fired in August.

Long filed a lawsuit Tuesday in Cook County Circuit Court against the Chicago Department of Aviation and United.

The suit alleges Long didn’t receive proper training to respond to the situation and that United should have known security officers would use physical force. Days after the incident United Airlines CEO Oscar Munoz said he felt “ashamed” watching the video and promised to review the airline’s passenger removal policy.

Spokesmen for United and the city say they haven’t yet received the lawsuit and declined to comment.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)