(NewsNation) — A policy implemented by Southwest Airlines to accommodate plus-size passengers has created conversation on social media.

On Southwest’s website, it says customers “who encroach upon any part of the neighboring seat(s)” can book more seats next to them before traveling. Customers will then be refunded the cost of the extra seats.

In a number of videos making the rounds online, plus-size passengers demonstrate how they also successfully get a second seat for free just by asking for one at the departure gate.

Southwest said the armrest is considered the “definitive boundary” between seats.

“We’ve had a long-standing policy for more than 30 years designed to meet the seating needs of customers who require more than one seat and protect the comfort and safety of everyone onboard,” the company said online.

Industry experts say the unpublicized policy generates customer loyalty for Southwest — but at a cost.

“If airlines do give seats for free to certain groups of people, obviously, there’s going to be a certain amount of public backlash for the people that are paying,” travel expert Katy Nastro, with Going.com, said, adding the practice can also cut into the airlines’ bottom line.

It’s also a lost piece of profit that airlines are giving up, Nastro said.

Traveler Stephanie Lanciani says the policy makes flying fairer and more comfortable for everybody.

“Much like people, equity comes in all shapes and sizes,” Lanciani says.

While the Southwest policy is going viral, there is confusion about the policies of other airlines. The general requirement is that plus-size passengers purchase two seats, which can discourage them from doing any air travel.

The policy will be put to an extreme test in the weeks ahead.

AAA predicts air travel between Christmas and New Year’s will be the busiest in U.S. history, with 7.5 million people taking to the skies.