Fare combination rules and "Personalized Pricing"?
 

I've spent a lot of time lately watching fare buckets, as I started keeping an eye on R/RN for an upgrade on an upcoming flight. But while watching them, I've noted a lot of other strange fare bucket mechanics occurring, and am wondering if there's any rational explanations for them, other than: a) airline revenue mgmt whim, or b) IT systems errors.

First, there's this thread I started a few days ago, when I started noting discrepancies:
Fare bucket inventory discrepancies CO vs. UA vs. booked?

(Note to sbm12 -- it turns out that the view on the existing reservation in "View Current Reservations" is the most accurate of all, even though it omits buckets with inventory of 0. At least as far as R/RN is concerned, I snagged an upgrade with R1 showing on my current itin, where searching for the flight showed R0 in 100% of the cases I tried.)

Second, I'm noticing that the lowest-available fare bucket isn't always made available for sale on a single ticket, even if bookable separately. Sometimes the CO.com website will combine buckets on Int'l trips for you, and sometimes it won't. UA.com vs CO.com give different results, in this regard as well. You can also book the segments at the lower-priced buckets as individual tickets, while sometimes those prices are even higher.

For instance: CLE-ORD-HKG on 1/12, returning 1/18. Search CO by price and you get fare buckets K-K outbound, V-S return, at a total price of $1406. Build by segment, and you get Q-S/V-S at $1607 as the lowest available fares -- and if you click on the Fare Class display link, it will show you "K0" for the first two flights, EVEN THOUGH searching by a different method or Co.com or on UA.com will give you the lower fare and show availability K9 in those buckets for those segments.

The thing that really kills me here is that this happens with the R/RN buckets as well, not just revenue-purchase pricing. Searching certain city pairs will show different R-bucket results for the Int'l segment. Once you've booked it, the results under "View Current Reservation" seem to then be consistent. But there doesn't appear to be a reliable way to know in advance of purchase. I've let my ExpertFlyer account expire, but prior to it dying, EF seemed to be agreeing with the Co.com _search_ results -- which, as just noted, do not seem to be accurate in all cases.

Anyone else have experience with this? I understand getting different pricing from different sites and search methods. But any idea why fare buckets, including upgrade fare buckets R/RN, would be showing up differently for the same flights, same carrier??

That's called "married segment availability". If you search, you'll find out all about it. It's sometimes even more sinister, as availability can be different depending on which flight you're connecting to or from.

Perhaps this is just my misunderstanding, but I thought that the end result was still supposed to be consistent. In other words, once you ended building a PNR, the pricing process should have ended up with the same result??

Or, failing that, at least the fare bucket display should be consistent, even if you're disallowed from marrying them...

Or, failing THAT, that upgrade buckets shouldn't have anything to do with married segments...?

Not at all. Man words are used to describe airline pricing, but consistent is rarely (if ever) one of them. For example, the airline could be willing to individually sell CLE-ORD in K and ORD-HKG in K, but they're only willing to sell the longer flight as a V fare. Or the K fare could be non-combinable with the V fare.

Married segment availability can affect the price of a ticket in surprising ways. For example, I recently saw SEA-SFO-BOS // overnight // BOS-PHL price as a SEA-BOS S fare plus a BOS-PHL S fare, while if I just searched for SEA-SFO-BOS alone it booked into V. It actually was cheaper to book an extra segment for the next day, ticketed with a separate fare! (Quite different from what I usually see as hidden city ticketing.)

As mahasamatman mentioned, most of your observations are described by married segments. Moreover, inventory varies based on marketing carrier (CO123, UA123, US5123 may in fact be the same actual flight, but each of one those three airlines may sell different inventory, even if they may share their fares). All of this is par for the course in how airfare is priced.