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Comment by ghshephard | Hacker News Reader

I've always found it interesting how round trips in one direction cost different than round trips in the other. I.E. p(A,B,A) != p(B,A,B). For example, I booked a trip October 2nd to Oct 17th from Singapore to San Francisco.

On United,

  $1170 - SFO UA 869,UA 895 -> SING UA 896, UA 862-> SFO
  $1690 - SING UA 896, UA 862 -> SFO UA 875, UA 7991 -> SING

I guess it makes sense that travel in one direction on certain days might be more significant than the other, But I find the $500 difference (almost 50% increase) to be pretty impressive.

I waited a few days, and re-ticketed again, and the price dropped from $1690 to $1463 - so that's also odd.

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That's quite common within Europe, where a ticket from Warsaw to Zurich can be significantly cheaper than into the other direction.

In this case it makes a modicum of sense. Chalk it up to differences in purchasing power.

  I waited a few days, and re-ticketed again, and the price dropped from $1690 to $1463 - so that's also odd.

Not really. Airline pricing is very much based on mathematical models. When the system determines that the flight won't be sold for $1690 it lowers the price.

The trick is to fill every seat on the plane as expensively as possible, but not to leave any empty seats. Check out this article for details https://en.wikipedia.org/wiki/Yield_management .

In principle: There is no product going stale faster than an empty seat on a plane after the doors close.

OT: it drives me crazy that yield management is not applied to events. If you have only sold half the tickets for your concert, reduce the remaining tickets. hn, do something!

If they did yield management properly at events which tend to sell out they'd also be able to capture ticket scalpers' potential profits rather than attempting overly elaborate ID schemes to prevent ticket resale. Not sure that many people would be thankful for higher ticket prices, but some of them might prefer that rather than having to buy tickets within an hour of them going on sale via a booking platform that struggles to cope with the traffic spike.

I used to work for a ticketing company. I know some Major League Baseball teams were making efforts at "dynamic pricing" which was basically yield management. Some ticket brokers do this as well.

Their goal is to maximize income, not fill seats. If it was the last flight they'd ever fly, you'd expect the price of an empty seat to converge to zero (or well, the cost of the fuel to lift a person and their baggage above the clouds) as the gates close, but you also have to keep the price expectation high for the customers silently haggling with the online ticketing system for a better price.

> where a ticket from Warsaw to Zurich can be significantly cheaper than into the other direction. In this case it makes a modicum of sense. Chalk it up to differences in purchasing power.

Not just that. Everyone wants to be in Greece in August, not many people want to be in London.

Unless they're staying the whole month or the period is bracketed by major discontinuities, it isn't clear how that preference is relevant. A round trip is at least two flights. Why should the order of them matter?

Demand.

It's pretty easy to imagine that demand could be quite different. For example, flying to San Francisco before the Super Bowl is going to be much more expensive than flying out of SF.

In the summer there is a daily direct flight from Hamburg to Whitehorse in the Yukon to cater to all the tourists pouring in. They flood to the Yukon in last spring, and leave again in the fall. The flight is somewhere around $$800 one way, $1500 return.

If you fly the reverse time of that i.e. Yukon->Hanburg in late spring and then Hamburg->Yukon in the fall, you can do return for ~$300 - because the planes are almost empty.

There's not really any good reason to expect arrival costs to be the same as departure costs for a given location. For instance, it takes much longer to board a plane than disembark, which means there's a comparative premium on leaving from less efficient airports. So even if it weren't about maximizing price, you'd expect different costs for different directions.

I believe airline ticket prices are often based seat demand and availability. SFO is United's west coast hub, so it could be that they are routing most trans-pacific flights through there and demand for seats is higher as a result.

Most airlines run giant data analysis operations on schedule (date and time) passenger utilization and anything else they can collect to derive an optimal pricing strategy.

Most fares are updated once per day and these days even intraday is possible. Most everyone uses SABRE, Amadeus and one other as their reservation backends which have various limitations (Spirit is an example that doesn't but it's very rare and theirs sucks). There are also a ton of caches everywhere to speed up the process which affects latency and increases stale pricing. It's sometimes very chaotic as to what everyone will see.

Also keep in mind that A->B and B->A and A->C->B, etc all have a different optimal pricing structure which is why you get so many odd prices. None of the reservation systems can consider every possibility either, they often have to short circuit a search or it would take forever so you can get variations depending on when/where/from what you look for these fares. Dallas to Austin is pretty trivial to search but small airport in Texas to small airport in China is ridiculously complex as there are trillions of combos.

Landing slots at airports have different fees. If you the A is a very expensive airport (e.g. Heathrow) the price of flying from and to A can be higher than the reverse.

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