It all started with an overbooked passenger jet preparing to leave Chicago for Louisville, Ky.
It ended with a passenger, who said he was a doctor who needed to get home, being dragged off the plane and left bloodied and muttering repeatedly, "Just kill me."
The incident, captured on video by several passengers, created a giant public relations headache Monday for United Airlines, touching a nerve with a flying public frustrated with an industry that is reaping record earnings while squeezing more fliers into smaller seats.
The Chicago-based carrier said it was following procedure Sunday night when employees realized that the airline had overbooked the 80-seat jet and could not get enough passengers to voluntarily give up their seats.
The airline randomly selected the unidentified man to boot from the flight. Videos show him with blood on his lip, screaming as airport police yank him out of his seat, then pull him down the aisle on his back while some other fliers call out in protest. Later, he returns briefly to the plane and appears disoriented, with blood smeared extensively over his chin.
The overbooking incident comes in an era of record airline profits following a series of combinations that have put four carriers — United, American, Delta and Southwest — in control of about 80% of all domestic flights.
Airlines have collected billions of dollars charging for things passengers were accustomed to getting free, including checked luggage, entertainment and food.
At the same time, airlines have been reducing legroom and seat width for coach travelers and are flying each plane closer to full capacity than ever before.
Federal law allows airlines to overbook flights. But carriers try to avoid removing passengers against their will because it tends to spur sore feelings and, with viral video capability just a cellphone away, public backlash.
Airline and law enforcement representatives have refused to discuss details of the latest incident. But passengers who posted video of the tussle on social media said the man announced that he was a doctor who needed to return to work to see his patients. He also was heard saying he was being singled out because he was Chinese.
Passengers on the plane told various media outlets that the airline made an offer at the gate of $400 and a hotel stay to each person who would be willing to give up a seat voluntarily to take a flight the next day. The seats reportedly were needed for United employees to staff a flight from Louisville the next day.
Unable to get enough volunteers, airline employees boarded the plane, announcing that the offer had been increased to $800. Still, no one volunteered, and airport security officers removed the passenger.
A Chicago airport police officer who helped drag the man from the seat has been put on leave pending an investigation, the city's aviation department said.
"The incident on United flight 3411 was not in accordance with our standard operating procedure and the actions of the aviation security officer are obviously not condoned by the department," the agency said in a statement.
A United Airlines spokesman said the man was delaying the flight by refusing to give up his seat. The flight was delayed by about two hours, according to online records.
"We are focused on our customers, on getting them to their destination on time," United spokesman Charles Hobart said.
United Chief Executive Oscar Munoz said the airline is reviewing the conduct of his employees.
"This is an upsetting event to all of us here at United," he said in a statement. "I apologize for having to re-accommodate these customers."
But public relations experts say United could have handled the incident more tactfully, perhaps by choosing another passenger to remove or by offering greater compensation to free up a seat. United Airlines declined to disclose how much money it offered to passengers to voluntarily give up their seats.
"This is what we call in crisis management 'creating your own crisis,'" said Eric Rose, a crisis management expert with Los Angeles-based Englander, Knabe & Allen. "They created their own crisis and handled it miserably."
Although the incident may damage the airline's image, it probably won't do much harm to its bottom line. Investors appeared unshaken; shares of the airline's parent company, United Continental Holdings, closed Monday at $71.52, up 0.9%.
"This is going to have no financial impact on United," said Henry Harteveldt, an industry analyst with Atmosphere Research Group. "I don't expect them to lose any meaningful revenue."
He noted that most travelers choose airlines based on price, convenient schedules, the carriers' loyalty reward programs and whether their employers require them to fly on particular airlines.
This incident comes a few weeks after United Airlines refused to allow two teenage girls onto a flight for wearing stretchy, form-fitting pants because they violated the airline's dress code for employees and their family and friends.
That decision sparked swift outrage on social media, with critics calling the airline sexist and vowing to stop flying the carrier. It drew in celebrities, including comedian Sarah Silverman and actors Patricia Arquette and William Shatner, who chastised the airline's handling of the "leggings incident."
Even so, a trade publication for the public relations industry, PRWeek, last month awarded Munoz its coveted Communicator of the Year award for his "ability to connect and share with employees his vision for the airline, and get them to rally behind it."
The U.S. Department of Transportation allows airlines to overbook flights because a percentage of passengers routinely cancel at the last minute and airlines want to fill every available seat to squeeze as much revenue from each flight as possible.
In 2016, the nation's 12 largest airlines removed 40,629 passengers involuntarily from flights, a rate of 0.62 passengers for every 10,000 fliers transported, according to the Department of Transportation. That rate is lower than the 0.73 passengers per 10,000 fliers in 2015.
United had a rate of 0.43 in 2016, according to the agency.
Federal rules also require airlines to follow a set of procedures for overbooked flights. Airlines must first request that volunteers give up their seats in exchange for tickets on an alternative flight plus compensation, to be determined by the airline.
If an airline can't get enough passengers to volunteer, the airlines can remove passengers involuntarily. Under United's "contract of carriage" rules, the carrier may select passengers to remove from an overbooked flight "based on a passenger's fare class, itinerary, status of frequent flyer program membership, and the time in which the passenger presented him/herself for check-in with advanced seat assignment."
Federal rules say that airlines must also compensate the booted passengers for the disruption, based on how much later they arrive at their final destination than the scheduled arrival time of the overbooked flight. On domestic flights, the compensation ranges from 200% of the original fare to 400%, with a maximum of $1,350 per ticket.
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5:20 p.m.: This article was updated with additional analysis.
2:35 p.m.: This article was updated to include more details about the incident, a statement that an aviation security officer was suspended pending an investigation, and analysis on any financial effect on United.
12:05 p.m.: This article was updated to include new details about the incident reported in a Louisville newspaper and the federal rules that guide airlines on booting passengers from an overbooked plane.
1:27 p.m.: This article was updated to include comments from an expert about the impact this controversy might have on United Airlines' bottom line.