The Math Behind United Airlines’ Window To Aisle Boarding

24.10.2023 - 14:37 / forbes.com

United Airlines is re-introducing its WILMA window-to-aisle boarding process, which the airline says saves an average of two minutes per flight. This is not an insignificant savings. Ground time costs airlines an estimated $100 a minute. A $200 savings per flight, multiplied over the 4,900 daily flights the airline operates, means nearly $1 million in daily savings.

But is this boarding process the most efficient? Experts have conducted multiple studies to find the optimal boarding processes, and their findings differ.

Efficiency in the aviation industry is crucial for both airlines and passengers. Passengers want a seamless, stress-free boarding experience, while airlines need to minimize costly aircraft turnaround times to keep flights profitable. A recent study into average aircraft turnaround times at airlines worldwide found room for improvement. It was conducted by technology firm Assaia, which has developed Apron-AI, an aircraft turn optimization platform for the aviation industry.

The Assaia study looked at nearly 150,000 aircraft turnarounds at around 100 gates. It covered over 25 airlines at ten airports on three continents and 101 aircraft types. The study only considered turnarounds that up to 300 minutes. That is the cut-off point when the operation changes from a turnaround to where the aircraft is parked awaiting its next flight. The study only looked at short- and medium-haul narrowbody aircraft operations because those are the most time-sensitive.

The study groups’ average turnaround times range from 107 to 66 minutes. The average ground delays vary between eight minutes for the best performers to 26 minutes for the worst. The average ground delay can be made up by making turnarounds more efficient, such as improving the passenger boarding process.

The two minutes United saves boarding can also avoid flight cancellations. Delays have a watershed effect on the entire aviation network. The 18 minutes difference between Assaia’s study's best and worst performers adds up to an hour and a half over five flight segments daily. The cumulative delays can result in the last flight out being cancelled, particularly at airports with time restrictions.

There have been numerous studies trying to find the best boarding process. Study results have examined the impact of different boarding methods on turnaround times, airline costs, and overall passenger satisfaction. Their views differ. United Airlines' new boarding system, window-to-aisle, also known as WILMA or outside-in, has performed well on various models.

Some studies suggest that random seating, which low-cost carriers Southwest Airlines LUV , Ryanair RYAAY , and others use is the most efficient. As passengers board the aircraft, they rush