No one enjoys boarding an airplane. It’s slow, it’s inefficient, and often undignified. And that’s without even getting into the ethical quandary of so-called gate lice, the anxious passengers who cluster at the gate before their group is called. But at least one part of the process doesn’t need to be disrupted. When it comes to shunting slow-moving passengers to the front of the queue, such as those requiring assistance or with small children, the airlines have it exactly right.
That’s according to a new paper published by the American Physical Society by a team of Norwegian authors led by Sveinung Erland, which shows that it is a resounding 28% more efficient to allow slower passengers to board first. “This is a universal result,” the authors observe, “valid for any combination of the parameters that characterize the problem.”
Airplane boarding might not seem the most obvious preoccupation for physicists. But the inefficiencies in the current system—boarding by group, from the rear of the plane to the front—have resulted in a series of academic studies trying to solve the issue, perhaps inspired by researchers’ own experience of the interminable wait to board. Meanwhile, practical tests, including on the television show MythBusters, have proven incontrovertibly that almost anything would be better than the system currently in place.
Researchers had long suspected that it might be quickest to start with slow-moving passengers, but the APS paper “was a demonstration of that fact” using “some fairly sophisticated math,” astrophysicist Jason Hyrum Steffen, an assistant professor at the University of Nevada, Las Vegas, told Quartz. He gives the analogy of filling a jar with rocks and sand. If you put the sand in first, followed by the rocks, he said, “you can’t fit it all into the same container.” But if you start with the rocks, “you can pour the sand in, and it will fill in all the gaps.” Here, the slow-boarding passenger are the rocks, while the quicker ones are like grains of sand, trickling between them and filling the spaces.
Though not involved in this particular paper, Steffen is no stranger to the problem of how to board passengers. For more than a year, he told Quartz, he found himself consumed by it, while mowing the lawn or taking a shower. Eventually, in what he describes as “an act of desperation,” he sat down and solved it in a matter of weeks. “I needed to either stop thinking about it, and move on to something else, or find a solution.” His work was eventually published in the Journal of Air Transport Management in 2008, with a follow-up in the American Journal of Physics in 2011.
His own method, which many consider to be the most efficient, boards passengers in a series of waves, with the first passengers called to board seated in window seats two rows apart—first 30A, then 28A, then 26A and so on. Next, the same for the other side of the plane (30F, 28F, 26F). The process continues with odd row window seats on either side, middle seats, and finally aisle seats. Each person can sit down within moments of one another without getting in anyone’s way. In field tests, it proved to be almost twice as fast as most conventional methods, and 20% to 30% faster than have-at-it, entirely random boarding—which is also faster than the method used by airlines. (He too would board slower passengers requiring assistance first.)
Intuitively, at least, you’d expect boarding from back-to-front to be the fastest way to get passengers onto the plane. But in actual fact, says Steffen, “anytime you want to speed up the boarding process, the only real way to do it is to have multiple people sitting down at the same time. The question comes down to this: what is the best way to do that?”
People have objected to Steffen’s method on the grounds that it would be hard to enact—boarding people seat-by-seat sounds a little tortuous, and does not account for people who miss their call while making a dash for the bathroom, for instance, or try to push ahead of their place in line. He disputes this. “It doesn’t really affect it at all. The worst case scenario is that it randomizes the boarding process,” he says, “which is already better.” Allowing people to board with their seat-mates, though slower than the optimum method, would also be faster, provided airlines kept to the two-rows-apart rule.
Late last year, London’s Gatwick Airport announced a two-month trial of different boarding methods, where passengers would enter the aircraft according to their seat number, including bringing them aboard front-to-back and starting with window seat passengers. (It’s not clear whether Steffen’s method was included in the trials.) Large digital displays showed which passengers were next in line.
“Early indications are that this new technique has the potential to reduce the overall boarding time,” Abhi Chacko, the airport’s head of enabling technologies and digital innovation said in a release in late October. “By communicating to passengers better and boarding passengers by seat number, we also expect to make the whole boarding experience more relaxing and, potentially, prevent large numbers of passengers rushing forward at any stage.”
While the results have not yet been announced, the tests could bring us closer to a quicker, more streamlined boarding process. But at least two features of the current boarding process are likely to remain the same: Slow-moving passengers will continue to get priority, as they should, and people prepared to pay to skip the queue will carry on as before, as unfair as that feels. Airlines may be interested in efficiency, but not if it gets in the way of helping them turn a profit.