DENVER (CBS4) — They take your order, serve up food and drinks, and come back to clean up. But should you tip your flight attendant? Frontier Airlines is encouraging it.

Flight attendants on the Denver-based airline began accepting individual tips on Jan. 1, according to the Chicago Tribune. Frontier made tipping an option three years ago but, until this year, flight attendants were required to pool tips.

“We appreciate the great work of our flight attendants and know that our customers do as well, so [the payment system] gives passengers the option to tip,” the Tribune quoted Frontier spokesman Jonathan Freed as stating.

Passengers who order refreshments get a prompt from Frontier’s payment system that they have the option to leave a tip.

JT Genter, of ThePoints Guy travel blog, shared a photo of the payment tablet displaying a message that reads, “Gratuities Are Appreciated!” It offers customers the options of 15 percent, 20 percent or 25 percent, “custom gratuity” and “I prefer not to leave a gratuity.”

“I’ve flown more than 350 flights on 51 different airlines in the past three years, but I’d never experienced an airline ask for a tip,” Genter wrote.

Genter expressed mixed feelings about tipping flight attendants.

“It feels a bit unprofessional for flight attendants to be seeking tips,” he wrote. But he conceded that it might motivate crew members to provide better service.

Some flight attendants and labor unions are reportedly opposed to the tipping policy.

“The Association of Flight Attendants International, a union that represents 50,000 flight attendants at 20 airlines including Frontier, opposes the tipping policy, saying attendants should instead be paid higher wages,” the Los Angeles Times reported.

Frontier Airlines Pilots Overwhelmingly Approve Contract

“Management moved forward with a tipping option for passengers in hopes it would dissuade flight attendants from standing together for a fair contract — and in an effort to shift additional costs to passengers,” the Tribune quoted AFA President Sara Nelson as stating.

The median annual salary for a flight attendant in 2017 was around $50,500, according to the Bureau of Labor Statistics.

“Industry experts say no other U.S. carrier gives passengers the ability to tip flight attendants, and they don’t expect other airlines to follow Frontier’s lead,” the Times reported.