The numbers should be taken with a couple of grains of salt. One grain: The survey only asked travelers if they'd ever tipped, not if they do so on a regular basis. Another grain: These are frequent flyers, who we imagine might be more inclined to take care of flight attendants they see on a regular basis.
Still: 27 percent is a pretty striking figure. Is it really a common practice?
"It's not common, but it's more common than you would think," says AirfareWatchdog's George Hobica.
Corey Caldwell, spokesperson for the Association of Flight Attendants, went a step further.
"Flight attendants do not accept tips," she said in an email exchange. "As first responders and safety professionals, a flight attendant's first priority is to maintain the safety and security of the passengers in the cabin."
In other words: They're trained safety professionals, not bartenders. That's a view echoed by Leah Ingram, author of "The Everything Etiquette Book."
"I think too many people associate flight attendants with waitresses, which is where this notion of tipping comes from," she says. "But I'd never put them in same category -- that is not his or her primary function. They're there to keep us safe and informed."
AirfareWatchdog's Hobica disagrees with the notion that a flight attendant would be offended by a cash tip. In fact, he says the extra cash could be welcome: Wages for the profession are tighter than you might think.
Still, if you want to reward a flight attendant for a job well done, but don't feel comfortable giving cash, there are alternatives. Caldwell and Ingram both recommend a letter to the airline praising the attendant for a job well done. And Hobica says that cookies and sweets are always welcome, as he found on a recent flight where he gave the flight crew a box of shortbread cookies.
"Sometimes they don't have time to eat," he says. "I think I bought [the cookies] at Trader Joe's for $3.99, but I got so many thank yous."
Matt Brownell is the consumer and retail reporter for DailyFinance. You can reach him at Matt.Brownell@teamaol.com, and follow him on Twitter at @Brownellorama.