Southwest Airlines said on Tuesday that it would start charging for checked bags, ending another longtime policy that had set it apart from other airlines as it seeks to boost revenues and cut costs.
Customers with high loyalty status will be spared from the fee, but all others will have to pay for checked bags for flights booked starting on May 28. The announcement reflected Southwest’s latest decision to drop a practice that had made it unique — and appealing — to customers.
The airline is also working to add premium seats with extra legroom and end its open-seating policy and recently started offering red-eye flights. When it announced those changes in September, Southwest said it would retain its beloved bag policy, which its own studies had found was a key differentiator for customers.
When Glen Hauenstein, the president of Delta Air Lines, was asked at an investor conference on Tuesday about whether the shift would benefit other carriers, he said: “Clearly, there are some customers who chose them for that, and now those customers are up for grabs. We’ll see how that plays out.”
But Southwest’s policy of allowing two free checked bags was costly. The airline carries nearly twice as many bags as its peers, which can slow operations, its chief executive, Bob Jordan, said at the conference.
And despite the airline’s studies showing the popularity of the policy, newer data on sales through third-party websites — which Southwest significantly expanded over the past year — suggest that the free bags were not as powerful a differentiator as previously thought.
That data “did not show that we are getting the same benefit from our bundled offering with free bags, which has led us to update the assumptions,” Mr. Jordan said.
Southwest has also faced intense investor pressure to make changes as it has struggled in recent years to contain costs. While other major airlines benefited from rising customer interest in premium and international travel, Southwest lacked the high-end offerings and routes to benefit from those trends.
In that, the hedge fund Elliott Management saw an opportunity. Last summer, it said it had amassed a 10 percent stake in Southwest and began pushing for changes, many of which the airline would announce months later. Elliott had also pushed for the ouster of Mr. Jordan, but abandoned that effort after the airline agreed to shake up its board of directors.
Customers who hold the airline’s top loyalty status, A-List Preferred, or buy its most expensive fare, Business Select, will still get two free checked bags. Some others, including its A-List status holders, will get one free checked bag. Remaining customers will have to pay an amount that the airline has not yet disclosed.
Some customers on social media and industry observers criticized the move.
“I think we’ll remember today as the day that Southwest died,” Brett Snyder, a former industry insider who writes about aviation at the Cranky Flier website, said in a post on Tuesday. “Its entire value proposition — everything that made it different — has disappeared faster than you can say, ‘Elliott Investment Management.’”
But some in the industry believe the effects will be more limited. At the investor conference on Tuesday, Scott Kirby, the chief executive of United Airlines, said the move was a “big deal” and could be good for Southwest.
“It’s the slaying of a sacred cow,” he said.
