Flickr/Curimedia The passenger-dragging incident sparked a year of controversy for United.

A former aviation officer who dragged a United Airlines passenger off an oversold flight last April is suing the airline and the Chicago Department of Aviation,ABC 7 reports.

In the lawsuit, the former officer, James Long, claims he wasn’t properly trained to handle passengers who misbehaved.

Long also argues that he was fired on unfair terms and subject to slander after videos of him and other officers dragging the passenger off the plane went viral.

A former aviation officer who dragged a United Airlines passenger off an oversold flight last April is suing the airline and his former employer, the Chicago Department of Aviation, ABC 7 reported on Tuesday.

In the lawsuit, the former officer, James Long, claims that he wasn’t properly trained to handle passengers who misbehaved and that United “knew or should have known” that calling aviation officers to “remove a passenger who was refusing to leave their plane would require the use of physical force.”

Long also argues that he was fired on unfair terms and subject to slander after videos of him and other officers dragging the passenger off the plane went viral.

Long pointed to several tweets shortly after the incident from Ginger Evans, the commissioner of the Chicago Department of Aviation who is also listed as a defendant in the lawsuit; one said its officers were not armed “for good reasons.” At the time, Chicago aviation officers were pursuing an effort to carry guns while working.

The lawsuit also says Long suffered “mental anguish” after his termination.

A United representative told Business Insider: “We have not been served with this suit and are unable to comment.”

United was widely criticised for its handling of the incident and the first response by its CEO, Oscar Munoz, in which he called the passenger “disruptive and belligerent.”

Munoz later issued a second apology expressing regret at how the incident unfolded.

“I deeply apologise to the customer forcibly removed and to all the customers aboard,” he said. “No one should ever be mistreated this way.”

The passenger, David Dao, lost two front teeth, broke his nose, and got a concussion, his lawyer said. Dao’s family threatened to sue the airline, but the two parties settled out of court.

Since then, United has been the subject of controversy, most recently about its treatment of pets. The airline has had several recent incidents in which an animal died on or shortly after a flight or was sent to an incorrect destination.

In March, after three dog-related incidents in one week, United said it would temporarily stop transporting pets in the cargo holds of its aircraft as it reviewed its pet transport program.

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