Why do airlines seat people the way they do?

I think you’re making a broad generalisation based on the practices of a few airlines.

There are actually many different boarding procedures, which depend on the airlines policies (including whether seats are assigned or not), aircraft type (size, number of floors, classes), airport equipment (number and position of bridges/stairs), use of bridges, stairs and buses, and more.

• Group boarding is for instance a practice of Southwest, where groups (other than the priority group) are (AFAIK) based on check-in order (so that the earlier you check-in, the earlier you board — this is to encourage you to check-in early I suppose).

• Many airlines have no order at all on smaller planes (that’s the case of most airlines in Europe, both LCC and incumbents on most single-aisle planes). Some (mostly LCCs such as Easyjet or Ryanair, but incumbents operating smaller regional-type jets also do it) will favour using stairs over bridges so they can use both the forward and aft doors (there will then be a split of passengers based on row numbers at the). Of course, this requires assigned seats.

• On larger planes the back-to-front policy is usually the norm. This may be combined with the use of several bridges (often just premium classes v. coach, but you other combinations are possible).

As others have pointed out, there have been many studies on the topic, but the most efficient methods (IIRC, they involved doing even rows back to front then odd rows back to front, and/or “outer” (windows) to “inner” (aisle) seats), but are way to complex to implement in real life. Even then, the most efficient method may still vary based on aircraft size, fill ratio, passenger typology (single business traveller which knows exactly how things work v. families with children and lots of bags who don’t even know how seats are numbered…).

It’s to create an artificially scarce commodity (earlier boarding rights) which can be sold.

I’d suspect random free seating to be fastest with business travellers (as on the old NY-Boston shuttle) who will just get on and take a seat. A bunch of one-trip-a-year tourists will probably slow the whole process up re-arranging bags and trying to get seated passengers to move so they can be with their companions.

United and Delta are definitely using a more ordered method of boarding aircraft. They have (in most places that I travelled YMMV) physically separate queues for different groups of boarding passengers and will turn a passenger away if they attempt to board at the wrong time.

For example with United (the last airline I flew with) the groups are:

1. First class
2. Premium club etc
3. First coach (from experience window seat)
4. Second round of coach
5. Third round of coach (from experience aisle seat)

The also highlight the currently boarding group on displays. Thus it is easy to see what group is boarding and there is no congestion at the gate.

It actually makes more sense to assign groups semi-randomly, so that you get an (ideally) even distribution of group members throughout the plane. (So that, if you have 50 people all in the same group, none of them is standing next to each other.)

That would mean you don’t have 12 people on the same 2 rows all clogged together fighting over seatbelts and overhead storage, but everyone gets a little space to work with until the next group comes in, at which time hopefully the previous group is already (almost) seated.

This may be one reason you sit down, maybe with a seatmate that’s in the same group, but the person sitting between you may come along quite awhile later.

Of course, if you’re in the last group, you’re probably out of luck regarding overhead storage, but what else is new?

This is a pretty straightforward problem to simulate, and solutions are enhanced by studying actual passenger boarding experiences. The basic statistical / heuristic solutions are perturbed by people traveling together, frequent flyers that arrive late, people that have to get something out of their luggage or go to the bathroom, etc. In a pool of 100-200 people these can be significant factors.

The airline has a vested financial interest in getting everyone on board and seated as quickly as possible, and, to a somewhat lesser extent, in a way that doesn’t piss off the passengers.

The airlines study this continuously and it’s turned out be a lot less ‘inefficient’ than it seems.

For example, American Airlines studied this and found random order is fastest. See here: Best boarding strategy for airlines: random, study says

So, if random is best timewise, a particular airline’s procedure is based on customer benefits and expectations. Premium flyers will always get priority boarding so they can get the best overhead bin space. That’s it.