Oscar Munoz said "this will never happen again", adding that the last Sunday incident, which knocked $1 billion off the firm's share price, was a "system failure".
Speaking after flyer David Dao was removed from a flight with such force that he was apparently knocked out, Munoz told US news station ABC News: "That is not who our family at United is."
He went on to say "you saw us at a bad moment" and that he felt "shame and embarrassment" after the passenger was dragged from an overbooked flight.
Munoz vowed it would never happen again to a seated passenger on any of United's overbooked aircraft.
Asked whether Dao was at fault, he said: "No. He can't be. He was a paying passenger sitting on our seat in our aircraft and no one should be treated that way. Period."
It came after Munoz issued his third statement in as many days over the incident, offering his "deepest apologies" and saying it is "never too late to do the right thing".
He pledged a full review of the circumstances, and said: "No one should be mistreated this way", ABC News reported.
Despite initially saying Dao was "disruptive and belligerent", Munoz added that he certainly "deserved an apology".
He added: "It was a system failure, we have not provided our front line supervisors and managers with the proper tools, policies, procedures that allow them to use their common sense."
The 69-year-old grandfather was seen being ripped from his seat after refusing United Airline's $1,000 in compensation as he said he had patients to see the following day.
As Dao was forcibly removed his head was slammed into a nearby seat rendering him semi-conscious and blood streaming from his nose and mouth.
Dao was undergoing treatment for his injuries at a Chicago hospital, according to lawyers for his family.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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Doraiah Chowdary Vundavally is a Software engineer at VTech . He is the news editor of SocialNews.XYZ and Freelance writer-contributes Telugu and English Columns on Films, Politics, and Gossips. He is the primary contributor for South Cinema Section of SocialNews.XYZ. His mission is to help to develop SocialNews.XYZ into a News website that has no bias or judgement towards any.