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Airplane boarding simulations (menkes76.com)
51 points by ColinWright on May 4, 2012 | hide | past | web | favorite | 54 comments

None of these simulations seem to take into account the usual activities that delay boarding:

* Not all of first class boards early, many flyers stay in the lounge till later and then hold up the aisle getting their bag into the overhead

* Passengers board together regardless of boarding order. Friends flying with an elite member can board early and not with their group.

* When the overhead is full passengers must swim upstream to bring their bag to be checked.

* Although there are plenty of bathrooms near the gate, many passengers insist on using the lav the minute they board. They again end up swimming upstream holding up the queue

* Seat stealing - whether intentional or not, some passengers help themselves to a roomier exit row seat (or on one occasion I've seen them in first class) hoping no one shows up to take that seat. Once the passenger with that seat arrives, the original passenger has to get their belongings, perhaps clear the overhead and again possibly fight their way against people boarding.

Southwest's self serve seating helps in some regards, but this style of boarding will never be used my the major carriers - at least in the U.S.

edit: typos

I prefer Southwest's self serve style because it rewards those who check in earliest. Well, that is, if you consider it rewarding to be the first on and first off (as I do when I get to sit in row 1).

On a recent flight using Azul (Brazil's "Jet Blue", same owner), people were boarded via the front and back at the same time. First time I had seen that, though not sure if it was any quicker. Perceptions of quickness are often dependent on where you are sitting.

Southwest's procedure used to be better when you had to get to the gate to get your number. That really encouraged people to get to the gate early. Now that you can checkin at home you can waltz to the gate.

I flew Virgin Australia within Australia a few weeks ago and they did front and rear boarding as well. I'm also not sure if it was any quicker.

But for heavily elite flights, wouldn't that work as "random" after the top tier?

Maybe this is completely dumb and impractical, but could there be a way to remove the seats from the plane, individually or in groups, maybe on a track (overhead?) like a roller coaster, so that there could be a large boarding area with plenty of room for people to get situated. Then once everyone is in their seat, the seats would roll and lock into position.

This would also allow you to quickly deplane, but have the next group of passengers already seated, ready to slide into the plane.

The boarding problem is human, and also spacial. And you can't really get rid of the humans, but you could change the space.

Freight transport has been containerized, how can we do it to passenger transport?

I discussed this some years ago with an airline engineer. There are many, many practical problems. A pressurized fuselage with a separable section big enough to load passengers on and off is one of the simpler problems. I was left with the impression that it will never[#] happen.

[#] "Never" is a long time. Certainly "not soon"

I was thinking weight would be the biggest problem. Maybe with new materials its not a problem.

We have these automated warehouses and factory floors with robotic carts that can precisely navigate, pickup and deliver loads without a lot of infrastructure needed, that's kinda where I'm coming from.

I'm thinking the solution would have to work with the existing sized doorways for it to be adopted.

The real alternative is to have a mock seating area with ov erhead bins. Everyone gets settled, the the bins are loaded and locked into place, and the passengers walk on without hand luggage. They then know where to sit, and don't spend time futzing with the bags and bins.

Well, you could do it like the cargo version of the 747: fold up the nose and load stuff straight in from the front. (Of course this requires having an upper flight deck like on the 747.

Realistically, there's lots of ways to handle the boarding/alighting process better, but we're talking massive extra expense in new planes and airport modifications in order to shave ten or fifteen minutes off the turnaround time. Probably not even that much, since passenger loading and unloading generally isn't the rate-limiting step.

Everybody has opinions on how airline travel can be improved, because airline travel provides people with many hours of downtime with nothing better to do than to think about how their experience could be improved. (This is also the reason there are so many stand-up comedy bits about airline travel.) It's probably much more profitable to think up ways to improve processes which most people don't see regularly, like... I dunno, concrete pouring or tree felling or fiberglass bending or... other things which don't spring immediately into my mind because I can't see them out the window thus demonstrating how obscure they are.

> Freight transport has been containerized, how can we do it to passenger transport?

A good first step would be to get back to having the a majority travelers check their luggage. A lot of the delay is by everyone bringing overflowing carry on luggage when the planes don't have room for every one do so.

A behavior that the airlines must endorse since it's encouraged by their fee structure.

More impractical than dumb, I think.

The machinery to get the seats in/out will be heavy, mechanically complex. This eats into revenue. Might not even work with existing airplanes.

You'd need to have machinery in the boarding lounge - at every airport the plane visits.

You don't really need this everywhere - people can just get on/off in the legacy mode - but when you visit an airport that lacks the gear you're just hauling dead weight around.

Okay, so we design a plane from scratch, and retrofit the terminals in the US ... but then you've got a plane that can only be used in the US. And one that can't be resold to Elbonia Airways when Northwestern is done using it.

Yeah, it would def need to be easy and cheap to retrofit. Almost like Segways built into the seat or something? Probably makes more sense to go after carry-on luggage. Getting 200 people to sit in assigned seats doesn't take that long, it's all the crap they bring with them.

In my opinion the carry-on luggage thing is a people problem, and so not easily hacked with technology.

Here's a clever idea I just thought of. The airline could keep the overhead bins locked while everyone boards. So everyone just comes in and sits down, keeping their belongings on their lap. (It seems like that would be a lot faster)

Then once the plane starts taxi-ing the overhead bins unlock and people can put away their belongings (since you have to wait at least ten+ minutes to taxi and take-off it seems like this wouldn't cause a slowdown.) Plus you'd get an extra efficiency because the person in the aisle can load the bags for everyone in his row.

Should I patent this ... :-/

So what if I'm the guy sitting in the window seat and I can't reach the bin unless I a) stand on the lap of the guy in 14C or b) ask 14B and 14C to move into the aisle while I do it?

What happens when a whole plane full of people try to move into the aisle while the aircraft is moving? FAA usually doesn't care for that one bit.

Was thinking the same thing. Or start charging $50 if you can't fit your carry-on under your seat.

Everyone schlepping all their crap through security and on to the plane is 90% of the problem.

Except we're not allowed to stand up during taxi. (And for the most part, I think that's a good policy, if everyone was standing up with their arms over their heads holding a rolling suitcase, a slight swerve could actually hurt people.)

Also, sitting down with a rolling suitcase on one's lap isn't really practical either.

Two issues I see:

* Some bags are too heavy / dirty (wheels on rollers accrue a lot of dirt) to keep in lap.

* These days because of the fees inevitably people carry too much luggage on board and have to check some of it after the bins fill up. Impossible to check luggage while plane is taxi'ing (unless there is some door to the cargo hold somewhere?).

I agree that the single biggest improvement in airline boarding should be with the airplane and airport design. The fact that there is only one entrance/exit makes for an automatic bottleneck and limits options. Most planes are equipped with a rear door or on larger planes a mid-door. They should allow those doors to be used during boarding. Seems that this would be the most cost efficient and reasonable gains should ensue.

the really big international flights sometimes board 1st (and higher, if we're talking about lines like singapore or virgin that have luxury classes) through separate doors from us proles.

of course, that only helps them....

I was bored on one flight and so I actually wrote a quick and dirty simulation while on the flight: http://blog.chewxy.com/2012/04/04/a-better-passenger-boardin... . My main complaint at the time had been the inefficiencies brought about by loading luggage in the overhead compartment.

I was actually quite surprised by the simulation - that queueing people into odd-even queues make for faster boarding.

Caveat: the code I shared on github is actually quite terrible. Ignore the code, look at the pretty charts

These simulations don't account for human choice on when they want to board. There are customers anxious to get to their seats, and so listen carefully for their zone boarding. There are customers who would rather spend time in the terminal than extra time in an upright seat so they wait until the very last minute to board, regardless of zone.

Increases in prices of checked baggage means many flights have more people carrying bags on, due to limited overhead space, there is more incentive to board as early as possible. If you don't have a carry-on that needs to go in the overhead bins, the incentive to board on-time or early is lower.

Southwest airlines, mentioned here quite a bit, incentives customers to board early (if you want a good seat, you need to get on early to choose it) and to check in early (they can better gauge % checked-in because you are rewarded for confirming with the airline 24 hours in advance). Their policy to allow free checked bags is a nice courtesy but it also means more customer check bags, reducing the time to store things in the overhead which leads to less time at the gate. Free bags is a financial play, just not in terms of additional revenue but as cost savings.

My experience (in the UK) is that the time is dominated by people being slow to put their bags away, or putting bags away then blocking the aisle while they take off jackets or getting bags back out to extract a book.

Also airlines tend to board from front and back simultaneously, which isn't always an optimization as people join the shortest queue regardless of where their seat is.

Surely airlines can just do this empirically rather than rely on simulations. Why not just A/B test a bunch of different boarding methods on different flights and time what works the best?


Every method of boarding will require training the flight crew, ground crews at the airport. A non-trivial expense to change over from A to B. And then back.

Departure times are measured down to the minute. Miss your time and much activity downstream is affected - pax connections, gate use at destination airport, flights downstream.

And so on. I'm sure that they do use A/B testing or something like that ... but they do a whole lot of simulatin' first.

Stop charging fees to check bags, and start charging fees for carry-ons. Airlines should WANT checked baggage. And so should TSA.

Airlines LOVE baggage fees. They're tax free. I wouldn't be surprised to see airlines reduce ticket fees and just boost bag fees for more tax-free revenue.

Reference this Hipmunk visualization: http://visual.ly/air-travel-baggage-fee-revenue-timeline

Apart from the tax status, it seems that baggage fees are an effective way to achieve market segmentation.

Would the same simulations run on a wide-body 2-aisle plane (such as A380/777) have substantially different outcome? It feels like they board in the same amount of time as a single aisle.

Banning carry-on luggage that doesn't fit under the seat would be a great place to start.

I talked to a crew member once who said that before they allowed carry-on luggage the boarding process took less than half the time. She really missed those days.

This is why Spirit started charging for carry-on bags. However, I don't think they allow free checked bags.

No, Spirit started charging for carry-on bags because their business model is to sell you a ticket for as low as possible and charge a ton of fees to make up the difference.

I thought the fastest was back to front, but alternating left and right side for each row. In other words, board the left side of last 10 even rows and the right side of last 10 odd rows at the same time, then let right/even, left/odd people in, then move on to the next 10 row, etc.

There was a research paper on that few months ago, and it was on HN. Does anyone remember details?

How about this idea:

Much of the congestion is caused by people stowing their bags overhead further down the plane than their seat, then having to reverse against traffic for X rows to sit down. Also there is a large fixed time cost once the overhead bins fill up and X passengers are forced to check their bags; they have to haul them all the way to the front against traffic.

What if a system was installed at the security checkpoint that recorded whether a passenger were boarding with a suitcase, and then assigned them a bin overhead. The bins would have small LED screens that displayed the passenger's name or seat number. An algorithm would match the bins to the nearest seats, and reduce or possibly eliminate downstream luggage-stowing. It would also be able to tell passengers that they were too late, the bins were full, and they would have to check their bags.

Difficulties --

   * some bags are small or irregular, can fit 2 in a bin  (measure bag during X-ray?)

   * initially people won't understand the system leading to chaos

Also people buy stuff at duty free, after the security checkpoint.

Most of the fail to understand that people like to board in groups based on association. eg, families like to board together. That mucks it all up.

Also, people are stupid and can't self-sort.

I must admit, Southwest's boarding always feels like the absolute easiest. You just get in line by number and sit wherever you want.

Regarding the mental qualities of travelers, I once witnessed this:

announcement: This is NOT a boarding announcement, please remain seated.

people: 80% of the people in the gate area stood up.

announcement: This is NOT a boarding announcement. When we do board, please pick up a sack lunch from the cart near the ramp.

people: 50% started forming a line near the ramp. 30% remained standing.

announcement: Please remain seated. We will start boarding in about 15 minutes. As you board the plane, please take a sack lunch from the cart near the door. Thank you.

people: Most looked around uncertainly and slowly sat down.

Person 1 near me: What was that about a lunch? Person 2: I don't know. I think they may serve you a lunch, depending on where your destination is.

Me: Envisioning a scenario where the attendent gives you a lunch if you are flying to Des Moines, but No Lunch for You! if you are continuing on to Los Angeles...

Does anyone know why back to front boarding is slower than random? That's doesn't make sense to me.

I'm assuming here just based on experience, but...you don't just go to your seat and sit down, you have to put your bag in the overhead bin, which takes some "aisle time".

in back-to-front, a line forms as you are waiting for people to store their bag. one person can take up [block] 3 rows of seats while he is fiddling with putting his bag overhead.

in random seating, people all over the plane are storing bags at the same time, instead of just 1 or 2 people.

I wonder what the percentage is of those delaying the line due to their slowness vs. the need to search out space.

The most aisle time I've taken on any flight might be 10 seconds, though most of the time it's zero since I prefer to store my carry-on below the seat when I can.

Instead of thinking of the problem as "how to get the group of people to sit down the fastest", the problem should be thought of as "how to get the group of people to put their bags away the fastest" (or at the same time).

From the simulation it looks like the bottleneck forms because each person takes a minute to put their bag away. So if you have 1 person in the last isle putting their bag away they are basically blocking the entire plane.

With random you get random people who can access the overhead compartments all over the plane which helps increase the number of people simultaneously putting bags away.

In my mind, it's the difference between having a singular thread of execution vs multiple threads.

The people in the aisle are units of work that need executing. In back to front, only the unit that is right at the front can actually be completed since only she is blocking the people behind her, who are in turn blocking the people behind them.

In a random setup, say the first person goes right to the back of the plane, there's every likelihood that the person behind her is not sitting next to her, which means that 2nd person can immediately reach his seat while she does the same..

Multiply this a good few times, and you'll see that a number of people proportional to the total number of passengers will always be getting seated at one time instead of just 1 or 2..

Doing it in blocks seems wrong. Instead, you should have 10 people board the plane in order of their seating, back-to-front, but have those 10 spaced evenly over the plane, so they have at least one row between them. They're all spaced out so they don't interfere with each other.

Then again I avoid airports these days because of the TSA.

Also back to front is usually done in cohorts - not a truly sorted stream of people. You end up with the people in seats 36 waiting to get around people in seats 32 just because they are in the same group.

I wonder how much plane size impacts the efficiency of system, particularly in the case of the random boarding process? I flew on Southwest and American Eagle last week and thought about this for a while. On Southwest people were able to choose their seat based on their position in line, but that choice was harder for some people than others. On American Eagle (pre-assigned seats) the plane was so small (16 rows of 3) that they didn't bother with boarding order outside of priority status. People randomly tried to get to their seat on the plane, but it seemed like that was faster on a per-person basis than Southwest. Perhaps choice slows the system down?

Conceptually back-to-front seems to make the most sense, but as the simulations show it's still not efficient. So instead of plainly loading back-to-front, load back-to-front but skip rows.

That is, if there are 25 rows on the plane, load rows 25, 20, 15, 10, and 5 at once in that order, and in the second wave load 24, 19, 14, 9, 4, etc. That way, the people sitting in row 25 will have a 4 row buffer between them and the next passengers to wait while they get seated and aren't blocking the next group (in row 20) from being seated.

Does that seem reasonable?

When I board planes I wait until the last possible second - I like to hear 'last call' before I join the queues. I don't take stupidly big carry on luggage, so why would I care whether I get on first or last?

I'd rather wait as long as possible and avoid being sat on the plane.

This probably ruins carefully planned boarding procedures. C'est la vie. But as it stands, the trouble with boarding is that there are plenty of people like me.

I would like to see real boarding times, also It would be nice to see the effect that all the bigger baggage (due to the baggage fares) that it is carried aboard. This is one of the biggest drags when boarding, even more with a full airplane as the last 20 pax are not going to find enough space for their hand luggage anywhere.

Beeing sorted into groups and numbers actually make's me feel like cattle instead of an airline passenger. I like the random boarding of Southwest and most European low-fare carriers.

It does not help that a lot of American companies do not use any of these methods, they use front to back in sections.

I can never understand the planes that board front to back. It makes absolutely no sense at all.

Easy. Next time you buy a fleet, ask Boeing for planes with 10ft wide corridors instead of 2ft.

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