The chief executive of United Airlines has issued a second, stronger apology after a passenger was dragged from a United Express flight, calling the confrontation "truly horrific".
Oscar Munoz said in a note to employees he continues to be disturbed by the events on Sunday night in Chicago.
He said: "No-one should ever be mistreated this way."
Mr Munoz was widely criticised for two statements on Monday about the altercation in which he described the 69-year-old man taken off the plane as "disruptive and belligerent".
Yesterday, Mr Munoz said that he was committed to "fix what's broken so this never happens again".
He pledged to review the company's policies for seeking volunteers to give up their seats, for handling oversold flights and for partnering with airport authorities and local law enforcement.
The company plans to share results of the review by April 30.
United Continental Holdings Inc (UAL.N) shares fell 1.1% yesterday.
Earlier, US President Donald Trump's spokesman said it was "troubling" to watch video of the passenger being dragged from the flight.
But White House press secretary Sean Spicer said it was unlikely the federal government would launch a separate investigation.
The passenger has been named as Kentucky physician David Dao.
Video of police officers dragging the passenger from the overbooked flight sparked uproar.
As the flight waited to depart, officers could be seen grabbing the man from a window seat, pulling him across the armrest and dragging him down the aisle by his arms.
United was trying to make room for four employees of a partner airline on the Sunday evening flight from Chicago to Louisville, Kentucky.
Other passengers on Flight 3411 are heard saying, "Please, my God," ''What are you doing?" ''This is wrong," "Look at what you did to him" and "Busted his lip".
Passenger Audra Bridges posted the video on Facebook, and it has been viewed hundreds of thousands of times, and triggered strong criticism of United Airlines.
Her husband, Tyler Bridges, said United offered $400 (£322) and then $800 vouchers and a hotel stay for volunteers to give up their seats.
When no-one volunteered, a United manager came on the plane and announced that passengers would be chosen at random.
It was reported yesterday that Vietnamese-born Dr Dao had previously been given a suspended jail sentence for illegally obtaining and trafficking controlled substances in 2004.
He also engaged in a sexual relationship with a male patient and would supply him with drugs in exchange for sexual favours. His medical licence was suspended, but partially restored in 2015.
A keen poker player, the father of five finished second in the World Series of Poker in 2009.