UA's website at least implies otherwise...

https://www.united.com/web/en-US/con...-services.aspx

Whilst it doesn't explicitly state what happens for UA->UA, it does have :

The file sentence there doesn't apply, as it's not "another carrier". The second sentence DOES apply as the 2nd ticket includes Star Alliance operated flights (ie, UA).

First off, there are no ulterior motives here. Never entered my mind to do something tricky regarding bags. Look, as a 1K UA offers to accept two bags each 70 lbs on a BE ticket. I was not aware of all the angles the pros in this thread look at, I was simply thinking of the convenience that the bags would go all the way to their destination. Of course, the savings by splitting this are enormous. We have our children living in Phoenix and between all of us that's 12-20 roundtrips a year at a minimum savings of around $ 1,000.00 per trip, potentially more because I am looking for GPU upgradeable fares. Comes out of Daddy's pocket. Again, we could live with retrieving bags at LAX and re-check again. Cumbersome and annoying, but not a major sticking point. I didn't ask the agent but what would happen if I would pay the extra $ 30.00 per ticket and purchase the regular economy fare. Would that still prohibit through check? In other words I am not clear, is it because we have to separate tickets with different fare classes or is it not right because it's BE?

Yes, all the time without any problems. But it is not that I have free bags on the TTP sector only and not on the BE ticket. I have two complimentary bags as 1 K on both. So please don't assume that I try to circumvent any baggage rules. That is a complete misunderstanding and was not the intention of my post. I am strictly talking about the convenience or inconvenience per se of grabbing the bags and recheck them. On the inbound trip,
though, that is sort of a given since we pick them up at customs and drop them before security.

I suspect you'd be OK with a regular economy fare, and at $30 more, you'd still be saving a lot.

Did not the supervisor state this was a BE fare issue?

UA-UA interlining is available for separate tickets, separate fare classes (although interestingly it is more difficult for the agent than UA-*A interlining).

So, there should be not problem on a non-BE ticket -- have you had a problem with that before purchasing the BE ticket this time?

Where does the UA site imply interlining between DL/AA and UA on separate tickets?
AA does not even interline to itself AA-AA, fortunately that is not an issue for UA-UA

According to Mrs. EX that's correct. Had a problem before once but that was quickly taken care of. In any case this is not something we can't handle.
I just could not imagine that routing the bags through all the way to their final destination could be so difficult.
As long as it is not illegal to purchase two separate tickets, then we are fine. Otherwise we have to take SW to LAX, just an even longer schlepp.
Thanks everyone for all the insightful information.

That's a whole different discussion and it does depend on the fare rules
https://www.flyertalk.com/forum/unit...keting-ua.html

It is not illegal to purchase two separate tickets. However, if you do that, it's better to plan a longer time at your connection airport for if your first flight is delayed.

While not "illegal" (as UA is not a governmental agency) it is very possible a violation of the CoC. That is an issue that needs a careful reading of the fare rules, exactly what are doing and what was your intent.

Detailed discussion in https://www.flyertalk.com/forum/unit...keting-ua.html

And it is very true, most airlines rarely try to enforce end-on-end ticketing restrictions except not to allow on a single ticket. But that is a discussion for the other thread.

Not had a problem with major carriers like Delta-KLM-AF

Simply buy a cheap TATL to Europe in Biz then switch to a EU coach fare (separate ticket) to another city. As long as Delta can sell the tickets it implies that the computers are linked relative to who and what baggage and no problem in interlining.

YMMV

I think you missed the point of this discussion -- interlining bags with separate tickets (UA & partners) is fine also with UA.
Just not, now, if the originating ticket is domestic BE. A limitation, reported earlier in this thread, DL also has.

It's potentially not about the BE fare, but the business class fare. Many (most?) of the cheaper business class fares (P and Z) don't allow end-on-end within the US. eg, here's a sample Z fare on the OP's route (LAX-NRT) :

Area 3 is Asia, so you can combine with domestic flights within Japan and anywhere internationally, but not with a feeder flight within the US (Area 1).

BE fares can't be combined with non-BE fares; end of story.

In most cases, the BE fares that I've seen only allow A-B-A ticketing when combined with other BE fares, but given how haphazardly UA has rolled them out, I don't doubt that there are some exceptions.

No end-on-end means they won't put it on one ticket / one reservation, and it means you may be technically violating the CoC.

But it does not mean that UA won't interline your bags if you buy separate tickets, and it does not mean that UA won't reaccomodate you if you miss your faux connection. It just means they don't have to.

The only new evidence introduced in this thread is that a supervisor told OP that they won't do this any more with BE fares. No one has introduced any evidence that United is being sticklers about checking bags through on separate UA tickets that violate end-on-end prohibitions, such as the discounted Z fare quoted above. We all know they could, given how the CoC is written. Doesn't mean they are.