DALLAS—Give Southwest Airlines credit. The lighthearted airline that cracks in-flight jokes can make even the most dramatic changes seem like a win for all travelers. The airline paraded people through a shiny new Boeing 737 MAX 8 decked out with rows of cushy extra-legroom and “preferred” seat sections,

One of the signature parts of the Southwest Airlines experience has long been the idea that boarding position mattered a lot because of first-come, first-served seating. With that characteristic going away, Southwest says it will "evolve" its boarding process.

The Dallas-based carrier hopes to return to profitability with its new assigned seating model and a handful of new red-eye flights.