So far as we know, Kate Hanni never got dragged off an airplane with broken teeth and a concussion.

Indeed, the Napa woman’s airline nightmare started when she was forced to stay on a plane.

Hanni, as some readers may recall, spent nine hours trapped aboard an American Airlines jet on the tarmac in Austin, Texas in 2006. Hanni and her fellow passengers were given no food, no water and no information during the long delay.

She turned the experience into a movement, forming an organization that successfully lobbied for an airlines passengers bill of rights.

Hanni has moved on from Flyersrights.org, but as this week’s debacle at Chicago’s O’Hare International Airport demonstrates, major airlines don’t always show respect for their paying passengers.

Cellphone videos of police dragging 69-year-old David Dao from his seat and along the floor of a United Airlines jet to make room on the plane for a United employee sparked justifiable outrage, which was amplified by United CEO Oscar Munoz’s initial defense of the airline’s actions.

As the videos spread across social media, it quickly became clear that this wasn’t the first time that an airline, needing to make space on an overbooked flight, resorted to intimidating behavior with passengers.

Los Angeles Times columnist David Lazarus told the story of a United passenger threatened with handcuffs when he refused to give up his seat in the first-class cabin of an overbooked flight. He was ultimately moved to a middle seat in the coach cabin and offered a refund of the difference in fare only after filing a complaint with the company.

There’s nothing new, or intrinsically wrong, about airlines overbooking their flights, and, according to U.S. Department of Transportation statistics, fewer than one-tenth of one percent of passengers are bumped annually — most of whom voluntarily trade their seats for cash, vouchers or other inducements to take a later flight.

Most passengers weren’t stranded for hours on the ground aboard planes without food, water or fresh air, but the airlines fought vigorously against any government protection for those who were.

It took more than three years, but Hanni and her allies persuaded federal regulators to authorize fines of as much as $27,500 per passenger for airlines that keep loaded jets on the ground for more than three hours. Airlines also must provide adequate food and potable water if a flight doesn’t take off within two hours after boarding, and passengers are entitled to operable lavatories, medical attention and ventilation. That’s basic health and safety.

United’s treatment of David Dao is a self-inflicted public relations disaster. It will produce bad headlines, editorials like this one and perhaps even a costly lawsuit settlement. But the long-term impact on United’s bottom line is likely to be limited because mega-mergers have left little competition in the airline industry.

Munoz, having shifted to full damage control mode, is promising to fix any flawed company policies “so this never happens again.” Consumers and their allies should keep a close watch to ensure that it doesn’t take an update of the passenger’s bill of rights to hold Munoz to his word.