Tuesday , October 27 2020

Letting slower passengers board airplane first really is faster, study finds, Ars Technica


    

      Yes, it’s annoying but –

             

“The more parallel you can make the boarding process, the faster it will go.”

      

      

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Physicists have been puzzling over this particular optimization problem for several years now. While passengers all have reserved seats, they arrive at the gate in arbitrary order, and over the years, airlines have tried any number of boarding strategies to make the process as efficient and timely as possible. Flight delays have a ripple effect on thecomplex interconnected networkof air travel and often result in extra costs and disgruntled passengers.

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Field tests bore out the results, showing that Steffen’s method was almost twice as fast as boarding back-to -front or rotating blocks of rows and – 428 faster faster than random boarding. The key is parallelism, according to Steffen: the ideal scenario is having more than one person sitting down at the same time. “The more parallel you can make the boarding process, the faster it will go,” he told Ars. “It’s not about structuring things as much as it is about finding the best way to facilitate multiple people sitting down at the same time.”

S. Erland et al./PR-ESteffen used a standard agent-based model using particles to represent individual agents.Illustration of the stepwise advance of passenger queue during the boarding process (N=8 passengers).This latest studytakes a different approach, modeling the boarding process using Lorentzian geometry- the mathematical foundation of Einstein’s general theory of relativity. Co-author Sveinung Erland of Western Norway University and colleagues from Latvia and Israel exploited the well-known connection between microscopic dynamics of interacting particles and macroscopic properties and applied it to the boarding process. In this case, the microscopic interacting particles are the passengers waiting in line to board, and the macroscopic property is how long it takes all the passengers to settle into their assigned seats.

“The ability of a passenger to delay other passengers depends on their queue positions and row designations,” the authors wrote. “This is equivalent to the causal relationship between two events in space-time, whereas two passengers are timelike separated if one is blocking the other and space like if both can be seated simultaneously.”

Erland

****************** (et al) ******************************************. treated the boarding process as an iterative two-step process. The passengers move until they either reach their assigned rows or are blocked by other passengers in the aisle, and the second step is how long passengers stand next to their designated rows to stow luggage and sit down.

The passengers form a one-dimensional line to fit into a matrix of seats. The researchers predicted passenger speed based on where each person was in line, which row they were seated in, and how long it took to clear the aisle. The model calculates whether passengers will eventually run into one another based on how far apart they are sitting and how far apart they are standing in line. Seated close together but standing far apart in line (a space-like separation) means there will be no interference; seated far apart, but standing close together (a time separation) is more likely to lead to interference.

S. Erland et al./PR-EThe researchers ended up with another counter-intuitive result: it’s actually 26 percent more efficient to let slower passengers board first. Furthermore, “This is a universal result,” the authors wrote, “valid for any combination of the parameters that characterize the problem.” Those parameters are the percentage of slow passengers, the ratio between aisle-clearing times of fast and slow passengers, and the density of passengers in the aisle.

Once again, it comes down to maximizing parallelism. As boarding progresses, those at the tail-end of the slow group will still be getting settled as the first influx of fast people begins boarding. For instance, three or four fast people might take their seats in the time it takes a single slow person near the back of the aircraft to sit down. Having all the fast people board first actually minimizes parallelism: the last fast passenger is already seated before the first slow passenger gets settled.

To illustrate, Steffen cites the well-known analogy of trying to pack rocks and sand in a jar. Put the sand in first and there won’t be much room left for the rocks. Put the larger rocks in first, and you can then pour in plenty of sand to fill in all the gaps around the rocks. “That’s the lesson of this [latest] result,” said Steffen. “If you’re going to pour a bunch of passengers into a vessel like this, and you’re dividing them up into slow people versus fast people, it’s better to get the slow people out of the way first and then let the fast people trickle in. “

Of course, even the best models are a simplification of an actual boarding process, where many other factors must be considered, including human behavior. First-class and frequent flyer passengers, for instance, are accustomed to preferential boarding. In an era where more people are not checking bags because they want to avoid extra charges, competition for overhead bin space can be fierce — and those who board earlier are more likely to snag precious bin space. Such studies are nevertheless useful, Steffen maintains. “It gives you a quantifiable result to consider when crafting policy,” he said. “And it’s counter-intuitive information, which makes it even more valuable because it shows where your intuition can lead you astray.”

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