It turns out the “friendly skies” aren’t so friendly at United, which is dealing with a well-deserved avalanche of bad publicity after it had a passenger literally dragged off an airplane, mouth bloodied, because he refused to give up a seat the airline said it needed for standby employees. After offering $800 and getting no takers, the airline selected four passengers, including Dr. David Dao, of Elizabethtown, Ky. Dao apparently was unwilling to leave and became upset, yelling that he’d been selected because he was Chinese.

What happened next should strike terror into anyone who’s ever flown. Horrified passengers witnessed aviation officers yank Dao, 69, from his seat so roughly that his head struck an armrest. Seemingly unconscious, blood streaming from his mouth, Dao was dragged by his wrists the length of the plane aisle. Somehow, he managed to escape officers and ran back onto the plane, muttering, “I have to go home,” over and over. He then collapsed and was hauled off in a stretcher.

An airline spokesman said Dao was asked to leave the plane several times before the aviation officers were called. The three other passengers who were selected by United left without incident, and Dao should have done the same. That said, his refusal to be bumped from the flight should never have resulted in the violent scene captured on video.

What rights does a passenger have in such a situation? Not enough.

We agree with U.S. Sen. Amy Klobuchar, who told an editorial writer that it may be time to build in additional protections to the airline passenger bill of rights passed in 2012. Those rights, which took years to get into law, came after multiple reports of passengers trapped for hours on tarmacs and denied basic necessities. The bill that Klobuchar helped push required, among other things, that food, water and medical treatment be made available to those trapped in a plane on the ground for more than two hours. Not something you would think had to be codified in federal law, but now comes an even more basic right: Not to be roughed up simply because an airline decided it needed your seat back. Incredibly, United CEO Oscar Munoz initially defended the airline, and used downright Orwellian language to apologize for having to “re-accommodate” a customer. Reaccommodating into a stretcher?

On Tuesday, as United’s stock price plummeted, Munoz issued a second apology, calling the event “truly horrific.” It certainly was.

Klobuchar said the incident “shouldn’t have happened,” and that the airline had options other than physical force. “They could have used other means to transport the flight crew,” she said. “They could have offered more compensation instead of putting it on the passenger. There is a price at which someone will get off.”

Klobuchar said that while airlines need wide latitude when it comes to safety issues, in a non-safety situation — like overbooking — “we need more protection for passengers.”

Overbooking has become an accepted fact of traveling life. Perhaps too accepted. As airlines attempt to squeeze costs, they typically sell more seats than they have, so they can have some no-shows and still have a full carrier. But no-shows average fewer than 10 percent, and more often than not are the result of missed connections — again, not the passenger’s fault. Some might call this the cost of doing business.

Still, in the interest of keeping ticket prices down, overbooking can be an acceptable business practice if the airline assumes responsibility for serving those customers who in good faith bought a ticket, made plans and should have a reasonable expectation of flying. That means bending over backward to take care of customers who are helping out with your business model. It means travelers who get upset at being forced to deplane should be assuaged, not assaulted.