United Airlines chief executive Oscar Munoz has apologised in a congressional hearing in Washington for an incident in which a passenger was forcibly removed from a flight.
Mr Munoz vowed to do better as he and other airline executives faced tough questions from legislators on Capitol Hill.
He told the hearing that 69-year-old passenger Dr David Dao was treated in a way that no customer should be handled, calling it a "terrible experience" that should never be repeated.
Dr Dao's lawyer Thomas Demetrio told RTE's Ray D’Arcy Show today that Dr Dao had been humiliated by the experience, as well as suffering serious head injuries when his head collided with the arm rest of his seat, knocking out two front teeth and leaving him concussed.
Mr Demetrio said he would be surprised if his client ever flew with United again.
United has taken a series of steps to reduce overbooking of flights since the April 9 incident and will raise to $10,000 the limit on payments to customers who give up seats on oversold flights, Mr Munoz said.
The airline also said it will improve employee training.
"This is a turning point for United, and our 87,000 professionals," he said. "It is my mission to ensure we make the changes needed to provide our customers with the highest level of service and the deepest sense of respect."
The hearing by the House Transportation Committee comes following worldwide outrage when Dr Dao was dragged off a United flight after refusing to give up his seat to a crew member.
The incident ignited a debate about poor service and a lack of customer-friendly policies on US airlines.
Transportation Committee chairman Bill Shuster said the hearing will give legislators "an opportunity to get much-needed answers about airline customer service policies and what is being done to improve service for the flying public".
United moved to head off criticism last week by reaching a settlement with Mr Dao and issuing new policies designed to prevent customer service failures. United and lawyers for Mr Dao have declined to disclose financial terms of the settlement.
United president Scott Kirby joined Mr Munoz at the hearing, along with senior executives of American Airlines, Alaska Airlines and Southwest Airlines.
Mr Dao's lawyer has praised the airline and Mr Munoz for accepting responsibility and not blaming others, including the city of Chicago, whose airport security officers yanked Mr Dao from his seat and dragged him off the United Express plane.
He had been waiting to fly to Louisville, Kentucky, on April 9 when the airline decided it needed four seats for Republic Airline crew members who needed to travel to work on another United Express flight in Louisville the next morning.
When Mr Dao and his wife were selected for removal, he refused to leave.
Video of the incident sparked more than two weeks of criticism and mockery of United. Mr Munoz initially blamed Mr Dao, but later said he was horrified by the event and called it a failure on United's part.
United has vowed to reduce - but not eliminate - overbooking, which occurs when more tickets are sold than there are seats on a plane.