United Airlines will no longer use law enforcement officers to remove passengers from overbooked flights after global outrage erupted over a video showing a passenger dragged from one of its planes in Chicago.

"We're not going to put a law enforcement official... to remove a booked, paid, seated passenger," United CEO Oscar Munoz told ABC News this morning.

"We can't do that," he said.

Mr Munoz said United would be examining its incentive program for volunteers on overbooked flights and that once a passenger is already seated, "your incentive model needs to change."

The Sunday evening incident caused a furore around the world as video recorded by fellow passengers showed airport security officers snatching Dr. David Dao from his seat aboard Louisville, Kentucky-bound United Flight 3411 and dragging him down the aisle and out of the passenger cabin.

Much of the uproar stemmed from Mr Dao's status as a paying passenger who was being removed to make room for additional crew members on the overbooked flight.

On Capitol Hill, powerful Republican and Democratic lawmakers denounced how Dao was treated and called for United to explain the situation.

Today US Senator Chris Van Hollen, a Maryland Democrat, announced plans for the Customers Not Cargo Act, which would prohibit the forcible removal of passengers already aboard an aircraft "due to overbooking or airline staff seeking to fly as passengers".

Mr Munoz said Sunday's incident resulted from a "system failure" that prevented employees from using "common sense" and that Mr Dao, whose face was bloodied during the altercation with security before takeoff, was not at fault.

An online petition calling for Mr Munoz to step down as CEO had more than 52,000 signatures by this afternoon, but he told ABC that he had no plans to resign over the incident.

Shares of United Continental were about flat in afternoon trading. They had fallen as much as 4.4% yesterday.

The backlash from the incident resonated around the world, with social media users in the United States, China and Vietnam calling for boycotts of the No 3 US carrier by passenger traffic and an end to the practice of overbooking flights.

Delta Air Lines CEO Ed Bastian defended overbooking as "a valid business practice" that does not require additional oversight by the government.

"It's not a question, in my opinion, as to whether you overbook," Mr Bastian said on a Wednesday earnings call. "It's how you manage an overbook situation."