Based on those findings, the aviation department fired one of the officers and the sergeant for escalating the incident and deliberately removing facts from an employee report.
The department suspended the other two officers – one for five days and one for two days – for the deliberate removal of facts from a report. The officer with the five-day suspension then resigned, according to The Associated Press.
The aviation department is reviewing its policies and procedures, with a report expected in early 2018.
United and the city have apologized repeatedly to Dao, and the airline reached an undisclosed settlement with him.
Dao's attorney, Thomas Demetrio, told AP that dismissing the officer who was not a sergeant was unexpected, but could resonate with other officers. He said the department's review of its policies should have been done the day after incident.
"In firing him, perhaps it will send a clear message to police and airline personnel all over the world that unnecessary violence is not the way to handle passenger matters," Demetrio said.