For over 50 years, Southwest Airlines has stood out with its open seating policy—passengers lined up, boarded in order, and picked any available seat. That system will soon end. Starting in January, Southwest will introduce assigned seating and its first premium seats, as part of a major redesign of its boarding process. Internally called “Project USA,” this initiative is more than a marketing shift—it’s a deep operational rethink based on one principle: if queuing isn’t good, boarding isn’t good.
Astrophysicist Jason Steffen’s boarding process, which boards passengers in a diagonal pattern, minimizes blocking and maximizes parallel activity. Simulations suggest it could reduce boarding times by 30–50%, but it relies on strict compliance and passenger discipline—hard to guarantee in practice.
Southwest’s new system will use a variation of the WILMA method—boarding Window, then Middle, then Aisle seats—to reduce aisle interference and speed up boarding. This approach is validated by queuing research, though the Steffen process is even more efficient in theory.
Boarding an aircraft is fundamentally a queuing problem—a test of bottlenecks, flow efficiency, and human behavior. The new plan introduces nine boarding groups and two parallel lines to create a smoother, more predictable flow.