United Airlines really wants to avoid another customer service disaster. And make flying its airline better in the process.

The airline said it is making 10 changes to prevent a repeat of what happened to Dr. David Dao, who was dragged from a flight because the carrier needed extra seats for commuting crew members. Video of the April 9 incident quickly went viral. Dr. Dao suffered a concussion and two missing teeth.

United had promised a review by April 30 of what happened aboard flight 3411 and changes to reduce involuntary denial of boarding or bumping "to as close to zero as possible."

"Our review shows that many things went wrong that day, but the headline is clear: our policies got in the way of our values and procedures interfered in doing what's right," said United chief executive Oscar Munoz in a statement.

Related: United CEO Oscar Munoz is walking a tightrope to fix an airline

United acknowledged four failures that day.

First, it shouldn't have called law enforcement when a security or safety issue didn't exist.

Second, it failed when rebooking the crew on an already packed and boarded flight.

Third, it failed to lure passengers voluntarily with sufficient compensation. Its agents didn't have the authority to offer more or find other ways to get passengers to their destination.

Lastly, United didn't prepare its employees for situations like the one with Dr. Dao.

So United came up with 10 policy changes and initiatives to reduce bumping and improve customer service. Some have already been implemented, and others will be rolled out soon.

What's changing at United