Tag: Wilma

Guest Post: Southwest Airlines’ Boarding Overhaul–When Queuing Theory Takes Flight

Providence College Professor Jon Jackson discusses a topic that every flier understands.

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.

Southwest’s new boarding plan is a live experiment in queuing theory and process design, balancing efficiency with customer experience. Boarding is a significant driver of turnaround time—a key metric for airlines. Every minute saved at the gate means higher aircraft utilization, lower fuel costs, and better schedule reliability, writes The Wall Street Journal (Oct 13, 2025).

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.

Classroom Discussion Questions
1. How do the WILMA and Steffen boarding processes differ in terms of efficiency, complexity, and customer experience? Why might Southwest choose a simplified version rather than the most efficient theoretical model?
2. What behavioral factors might reduce the effectiveness of Southwest’s new boarding plan, and how could the airline design around them?

OM in the News: The Airline Boarding Process

United Airlines has a plan to fix one of the most annoying parts of travel: boarding, writes The Wall Street Journal (Oct. 19, 2023).  United is bringing back a boarding method for passengers that it says is more efficient, hoping to shave up to 2 minutes off what is often a contentious process. It sounds simple: window, middle, aisle, or “Wilma.” When economy passengers board, those sitting in the window seat will go first, followed by middle seats, then aisles. Groups traveling on the same reservation will still board together.

Airplane boarding has become a Byzantine OM process that can frustrate customers and put airlines behind schedule, causing delays that can ripple throughout the day. We deal with this topic in Chapter 7, where five process and analysis techniques are introduced (see pages 284-288).

For airlines, boarding is a logistical puzzle as well as a psychological test as they try to balance speed, fairness and revenue. Earlier access to overhead bin space is often a perk for higher paying customers, who clamor to get on first. Carriers have tried tweaks like better signage and text-message alerts about when to head to the gate. The number of boarding groups has proliferated as airlines have sought to reward loyal customers, military, handicapped, etc., while keeping things running more smoothly.

 No matter what, crowding at gates and logjams on jet bridges seem inevitable. United said things have gotten even worse as travel has rebounded from the pandemic. Boarding times have increased by up to two minutes since 2019.

United has used the Wilma process before: But in 2017, it combined middle and aisle seats into a single group. Now, economy passengers in dreaded middle seats will board after those with window seats, followed by those with aisle seats. Basic Economy passengers will have their own newly created group and will be the last to get on the plane.

All airlines find that small reductions in that “turn” time can add up over the course of the day and allow for more flying, and all have different theories on the speediest procedure. But it seems no airline has found a panacea.

Classroom discussion questions:

  1. Check out some of our earlier posts on the topic by using the search engine on the right. Summarize the approaches tried.
  2. How would you tackle this problem as operations manger of an airline?