United Airlines chief Oscar Munoz apologised again for the forced removal of a passenger from an aeroplane last month as he testified in Washington.
He spoke at a congressional hearing convened after recent incidents exposed mounting frustration with US airlines and the flying experience.
Politicians on Tuesday pressed Mr Munoz and other executives, questioning practices such as overbooking.
Airline leaders said the incidents had pushed them to improve.
“We had a horrible failure three weeks ago,” Mr Munoz said. “It is not who we are. It is not this company and it is not … this industry.”
United has come under scrutiny for its forced removal of passenger David Dao from a flight on 9 April to make room for crew members.
The airline has settled a lawsuit and announced policy changes, including boosting the amount of money staff can offer passengers to take a different flight.
American Airlines also suspended an employee after a clash with a passenger over a baby pram.
Consumer advocates, and some politicians, said airlines should do more and raised the threat of greater regulation.
“As a general rule, I don’t believe in over-burdening our businesses with regulation, or re-regulating industries that have been successfully de-regulated,” said Rep. Bill Shuster, the Pennsylvania Republican who heads the committee.
“But I shouldn’t need to remind you that Congress will not hesitate to act, whenever necessary, to ensure your customers are treated with the respect they deserve. ”