By Alison Sider and Dawn Gilbertson

Passengers will tally Southwest Airlines' new checked-bag fees in dollars, but the airline has been counting minutes and seconds.

The end of "bags fly free" threatens to upend Southwest's fine-tuned operation. Flight check-in lines could grow because it takes time to pay for bags. The number of carry-ons is expected to rise as travelers try to save money, slowing boarding and threatening on-time departures.

In the months since announcing its new bag policy, Southwest has been studying how to free up precious airport minutes to account for the extra time needed. The Dallas-based carrier has added new tech in the lobby and at the gate and armed employees with data to avoid last-minute surprises.

"We're not just going to hope," said Andrew Watterson, Southwest's chief operating officer.

There is a lot at stake. Customers are already grumpy about the elimination of a decades-old perk. Starting Wednesday, Southwest will charge $35 for one bag and $45 for a second, with some exceptions.

That makes it even more critical for Southwest to maintain strong operations as a selling point. Year to date, Southwest has the lowest rate of cancellations among its main U.S. rivals, and its on-time rate is over 80% and inching closer to Delta Air Lines and United Airlines, according to aviation analytics firm Cirium.

For most airlines, bag fees are old news -- they have been around for more than 15 years. But it is a massive shift for Southwest and its customers, who are accustomed to packing heavy.

The change might not be noticeable at the airport right away. Most people traveling now booked their trips weeks ago when tickets still came with two free checked bags. But the impact will become more noticeable over the summer.

Customers spend about 60 seconds on average checking in at airport lobbies. Paying for a checked bag or two will lengthen that to 100 seconds, said Justin Jones, executive vice president of operations at Southwest. But eventually, once fees are phased in, the airline expects about 28% fewer checked bags.

More bags could end up at the gates. On Southwest's smallest planes with the smallest bins, there are usually five or six carry-ons that don't make the cut and need to be checked, Jones said. Once bag fees go into effect, the number of gate-checked bags on those flights could surge to 25, according to the airline's calculations.

The airline has already started deploying new technology to help head off those problems -- tools it says will learn and adapt during the ramp-up period.

A new "Lobby Awareness Tool," developed by Southwest's artificial-intelligence team, predicts wait times at airports based on flight schedules and passenger-arrival patterns. At times when lobbies could get crowded, extra employees will be deployed with iPads to keep long lines from forming.

Another tool known as Bebop, for Baggage Estimation Based on Passengers, aims to predict the number of carry-ons that will have to be checked at gates.

"By starting early, we're kind of training the model, the systems for this," Watterson said.

Work the airline has already done to shorten downtime between flights will provide more time to manage bags without dinging its on-time performance. New procedures for arriving aircraft have helped get planes to gates and start unloading bags about 90 seconds faster, Jones said.

Southwest is also rolling out mobile bag-tag printers so gate agents don't have to resort to the dreaded paper tags tied to bag handles with string. A new app for crew facilitates communication between flight attendants and agents during boarding so agents don't have to walk down the jet bridge to check on bin space.

In Chicago and Nashville, Tenn., the airline has been making airport announcements earlier to nudge passengers to gate-check before boarding is under way. The message emphasizes that it is free and saves the hassle of dealing with bulky luggage.

"Those have been testing really well," Jones said.

The airline doesn't expect gate-checking to be a scourge on every flight. By the end of the year, about half its 175-seat planes will be outfitted by bigger bins that Southwest says will fit passengers' carry-ons. Once the rest are finished next year, around three-quarters of Southwest's fleet will have the spacious bins.

Some customers say Southwest is fooling itself if it thinks the new process is going to go smoothly. Carry-on bags are already gumming things up, even on planes with the bigger bins.

On a full flight last week Wednesday from Phoenix to San Francisco, flight attendants made multiple announcements begging passengers to put their smaller items under the seat because the bins were filling up and they didn't want to gate-check bags and further delay the flight.

Tom Harrison, a finance executive from Indianapolis who has Southwest's top frequent flier status, says full bins have been an issue on several of his recent flights. On one, he says, a deadheading pilot's bag was taken out of the bin and brought to the front of the plane to make room for a passenger's bag. He isn't worried about his bag because he is among the first to board but says travelers in later boarding groups might face issues.

"I would be a little concerned about whether I'm going to get on the plane and find out they don't have room," he said about the changes Southwest is making.

Write to Alison Sider at alison.sider@wsj.com and Dawn Gilbertson at dawn.gilbertson@wsj.com

(END) Dow Jones Newswires

May 28, 2025 17:17 ET (21:17 GMT)

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