United Airlines said a man wouldn't give up his spot on a flight. According to witnesses, he was pulled screaming from his seat by security and back to the terminal at Chicago's O'Hare International Airport. (The Washington Post)

Hundreds of thousands of air travelers are denied boarding as a result of oversold flights each year, according to data from the U.S. Department of Transportation.

The incidents typically don’t escalate to violence, as in the case of the United Airlines passenger who was dragged into the aisle and off the plane after he refused to give up his seat on Sunday.

In that case, aboard a Louisville-bound flight originating at Chicago O’Hare International Airport, airline officials asked four passengers to give up their seats so crew members could fly. One man refused and police were called in. The man was pulled from his seat and dragged screaming through the aisle and off the plan and left bloodied and battered.

Videos of the incident set off fury worldwide, igniting a campaign to boycott United, and politicians asking for a congressional investigation. United’s CEO initially defended his crew’s action but later Tuesday apologized and called the episode “truly horrific.”

Whether it's an overbooked flight or getting stuck on a tarmac, this is what you need to know about your rights when common flight troubles come up. (Claritza Jimenez/The Washington Post)

In most cases when passengers are asked to give up their seat, they volunteer, the DOT data shows.  Of the nearly 500,000 passengers who had confirmed reservations and were bumped off flights last year,  about 40,600 were forced to give up their seats, according to DOT’s Air Travel Consumer Report.

United’s bumping record isn’t as high as some of its competitors. Last year the airline bumped nearly 63,000 passengers off oversold flights; 3,765 were involuntary. The figures does not include passengers affected by canceled, delayed, or diverted flights.

This chart shows the number of passengers denied boarding per major U.S. airline in 2016 and a comparison to the previous year.


(U.S. Department of Transportation)

Overall, the number of bumped passengers is small compared to the total number of people served by the industry.  The U.S. airlines highlighted in the DOT report served nearly 660 million enplaned passengers last year.  That means the number of involuntary denied boardings was less than one (0.62 to be exact) per 10,000 passengers.

American and Southwest airlines had higher numbers of passengers denied boarding because of the oversales. Southwest forced nearly 15,000 passengers to give up their seats, of 88,628 that were denied boarding last year on oversold flights, according to the data.

According to DOT, airlines set an annual low bumping rate of 0.62 per 10,000 passengers, which was the lowest annual rate since 1995, the earliest available in DOT records. That rate was down from 0.73 per 10,000 passengers in 2015, and below the previous record of 0.72 per 10,000 passengers 2002, according to the annual report on airline performance.


(U.S. Department of Transportation)

In the United incident, the airline initially said that Flight 3411 from Chicago to Louisville was “overbooked,” and that it asked for volunteers to give up their seats. When no one came forward, the airline picked four passengers to deplane. On Tuesday, United clarified that the flight was not overbooked, but that it needed four seats for off-duty crew who needed to fly to Louisville.