Consider the following bog-standard round trip — a trip from San Francisco to Dublin, booked using a United fare on the outbound and an Air Canada fare on the return.
For simplicity we have chosen a very specific set of flights on the outbound and want to cover them with one specific fare. On the return, we know exactly flights we want, and exactly what fare we want to use to cover the fare, but we're willing to change one thing.
The return portion of this trip is an Air Canada Rouge Premium Rouge fare, fare basis ELW38RCE.
Now, a fare engine finds two ways to satisfy this trip — do you see the difference? It is very subtle, it has to do with who markets the last segment.
The last segment can either be:
AC5437 ORD-SFO (operated by United) — booked as an AC B fare
or
UA1226 ORD-SFO — booked as a UA M fare
This is, by the way, consistent with the published rules for this fare — this fare books into B for AC flight numbers and M for UA flight numbers on the intra-area-1 portion of a transatlantic journey.
Code:
4 SFODUB 28DEC14 AC USD 1557.00 ELW38RCE STAY-03/12MBK-E
FARE CLS EXPLANATION BOOK CODES
-------- ---------------------- ----------
ELW38RCE LOW/OFF-PEAK SEASON WEEKEND PREMIUM E
ELW38RCE ECONOMY ADVANCE PURCHASE FARES
…
IF VIA AC E- FARES VIA ATLANTIC
VIA UA M REQUIRED WITHIN AREA 1
Now, if you were a travel agent, and you had the two choices shown above, which flight number would you pick?
The AC number with the AC B fare?
Or the UA number with the UA M fare?
Gotta go with "B", right? It's higher, it must be better, surely it earns more miles?
YOU CHOSE POORLY.
Here's how United translates that AC B fare into a United fare class:
That lovely AC B fare on the AC flight number becomes a United "U" fare!
If you had booked the UA prime flight number, you would have gotten M, instant 1K upgrades if PN is available, better position on the pecking list for EUA otherwise. Instead, you gambled, and you got "U".
Now, the UA view of the e-ticket knows you got a "B" fare on the AC flight number, but it doesn't exactly know what to do with that info, and it gives you a bonus piece of info incorrectly suggesting EI has picked up a new fifth-freedom route
I thought I understood codeshares a little bit, but this is crazy. How could anyone possibly know what this AC flight number "B" fare becomes on the prime UA view of the reservation, without actually booking the trip and seeing what happens? As far as I know, the mapping of "AC B => UA U" is not published anywhere.
This is not theoretical — I have a friend who actually booked this. What … what in the world should he do? Can he call UA and ask them why he has a "B" fare ticketed with a "U" fare class confirmed on the ORD-SFO sector? This seems disingenuous; if the AC B => UA U thing is not some kind of mistake, there's no reason for him to be asking a UA agent for UA B on the sector.
The booking class inventory on the AC transatlantic sector is no longer available, so I don't think he can call his OTA and ask them to amend the booking / flight number.
This is just weird. How in the world is anyone supposed to know what fare class to expect when booking a codeshare flight number? Based on the rules of this fare, I would've guessed an AC B => UA M translation. But if the actual mapping isn't published anywhere, what can you possibly do but buy and guess what you're going to get?