Southwest Airlines has rolled back part of its divisive policy requiring overweight passengers to buy two tickets on flights when they require a second seat because of their size. 

Under the budget carrier's revised rules, Southwest gate agents will arrange a free second seat for passengers who need the extra room on flights where two adjoining seats are available.

After an earlier rule change in January, Dallas-based Southwest required people needing a second seat to book and pay for it in advance. The National Association to Advance Fat Acceptance (NAAFA), an advocacy group, criticized the policy as "more restrictive."

The new update aims to promote "a more consistent and seamless experience for customers who require an additional seat," Southwest said in a statement to CBS News. 

When two adjacent seats aren't available on a flight, larger passengers will be rebooked on a later flight, the airline said. 

To avoid inconveniences at the airport, Southwest continues to encourage passengers who need more space to book an additional seat in advance.

After a trip, eligible passengers can request a refund for the extra seat by submitting a request to Southwest within 90 days of travel. To qualify, the flight must have departed with at least one open seat, and both seats must have been booked in the same fare class.

Katy Nastro, a travel expert at flight deals website Going, thinks Southwest loosening its policy is a good move for the airline. 

"We've seen Southwest dive into the sea of sameness in the past two years, getting rid of pro-traveler policies like bags fly free, and open seating, to name a few," she told CBS News. "This rollback feels like, for the first time in a while, Southwest is bringing back some of the LUV to its passengers." 

Southwest is publicly listed, and its shares trade on the New York Stock Exchange under the ticker symbol "LUV."

NAAFA also praised the policy reversal. 

"We commend fat travelers, influencers and activists for calling out recent cruel behavior by Southwest Airlines. Southwest has felt the pressure and responded, by restoring one aspect of their previous policy, allowing personnel to assign an extra seat at the gate if one is available," NAAFA executive director Tigress Osborn said in a statement to CBS News. 

Who needs a second seat?

Southwest explains in its "customers of size" policy that passengers "who encroach upon the neighboring seat(s)" are required to purchase "the number of seats needed."

A seat's armrest marks the dividing line between seats, the carrier stipulates. Southwest reserves the right to determine that a passenger requires a second seat "for safety purposes."

That policy went into effect in January, frustrating some customers who had previously been able to reserve two seats for the price of one. 

One TikTok user cheered Southwest's latest seating policy, saying, "You will no longer have to pre-purchase the seat as the only option to fly as a customer of size with extra space."

"This is the best news ever," she added. "If you know a fat person, spread the word." 

Plus-size passenger policies vary across the airline industry. 

For example, Delta Airlines asks passengers who require additional space to purchase an additional seat before a flight. That requirement applies to anyone who can't fit in a single seat without encroaching on a neighboring passenger, or who prevents armrests from staying down while seated, according to the airline's policy. 

United Airlines and American Airlines have similar policies. 

NAAFA's Osborn said that even Southwest's adjusted policy falls short of allowing plus-size passengers to travel with dignity, saying that if they can't afford to pay for a second seat in advance, they are "at risk of being bumped off their flight and reassigned to the next flight with a seat available."

"There is no guarantee of a time frame for that reassignment, and this will still be very disruptive and stressful for fat passengers," Osborn said.