UA put us on BA then arrived very late
 

We were booked on UA934 LAX-LHR on 2/12 and then UA938 LHR-BRU on 2/13.
When we arrived at LHR at 12:36PM which was already 1 hour 7 min delay, we were told that our next flight UA938 LHR-BRU (scheduled arrival at BRU 3:35PM) was canceled because the aircraft didn't come from SFO(?) due to mechanical problem.
When we were deplaned, the GA gave us a BP (BA404) which departed at 5:45PM (5 min late) and we ended up arriving at BRU at 7:51PM (only 1 min delay for BA404) compared to 3:35PM by UA938.

At LHR we asked the GA about earlier flight to BRU, but he said the next flight (I'm not sure which airlines) would depart at 12:50PM.
Since our flight UA934 arrived late UA couldn't get the 12:50PM flight for us, arghhh.
So we had to take the BA404 5:45 departure flight...

My question is should we ask UA compensation?

You sure could try, but UA paid BA to fly you there. Granted, UA had the original problem, but BA accepted your ticket (and the money from UA) to fly you, so your gripe is with BA for the delay, as it was their service that failed. UA provided you with an acceptable alternative, but BA failed to deliver on their end.

Again, UA is responsible for the delay between the original flight, and the scheduled BA flight, but not beyond that. UA acted as an agent for BA. WHen an agent (brick/mortar, or online) books you on UA, and UA is late, do you complain to the agent, or to the service provider?

With all due respect, isn't your answer "passing the buck" so to speak? The passenger contracted with United. It was United that put the OP on another carrier. The OP did not ask to be put on BA.

Oh, I accepted blame for the delay up to a point, and assessed blame beyond that outside of UA control to the company responsible for that part. Don't know how that is passing the buck. How could UA control the part that happened on another carrier as UA effectively (and contractually per the CoC) was only acting as an agent for them. Again, When one buys a ticket from an agent, they buy from them. Once a carrier accepts that ticket from the agent, they become their customer.

I guess the passenger could have not accepted the arrangement UA made with BA, and then could place a 24 hour blame on UA, but they didn't, they accepted UA's "outsourcing" of that segment. Hardly anything UA could do about it from that point. In fact, If BA had then had a cnclation for a mechanical, who do you think would have bought the room? Would BA say "All passenger's whose reservations and tickets are on us, but were bought on someone else, please return to that carrier. We ill take their money, and their passenger's but we won't take any of the risks involved." If the plane went down (god forbid, but it is an example) Would they say 150 souls onboard that bought tickets on us first hand, plus a few stragglers from other carriers? Would BA not pay the families of the survivors, but push that over to UA? That isn't the way things work. A carrier is responsible for travel on it's own metal, with a few minor exceptions for code sharing. Last I saw, UA does not code share, and therefore, (again, per the CoC) acts ONLY as an agent for the other carrier.

1st para in the CoC: A) THIS CONTRACT OF CARRIAGE SETS FORTH THE TERMS AND CONDITIONS ON WHICH UA PROVIDES AIR TRANSPORTATION TO PASSENGERS AND THEIR BAGGAGE ON FLIGHTS UA OPERATES, WHETHER SUCH AIR TRANSPORTATION IS PURCHASED FROM UA, ONE OF UA’S AGENTS OR FROM ANOTHER CARRIER. THE RULES CONTAINED IN THIS CONTRACT OF CARRIAGE ARE EXPRESSLY AGREED TO BY THE PASSENGER.

Same section, a few pages down: D) UA WILL BE RESPONSIBLE FOR THE FURNISHING OF TRANSPORTATION ONLY OVER ITS OWN LINES. WHEN UA UNDERTAKES TO ISSUE A TICKET, CHECK BAGGAGE, OR MAKE ANY OTHER ARRANGEMENTS FOR TRANSPORTATION OVER THE LINES OF ANY OTHER CARRIER (WHETHER OR NOT SUCH TRANSPORTATION IS PART OF A THROUGH SERVICE), UA WILL ACT ONLY AS AGENT FOR SUCH OTHER CARRIER, AND WILL ASSUME NO RESPONSIBILITY FOR THE ACTS OR OMISSIONS OF SUCH OTHER CARRIER.

Pretty straightforward, even BA takes responsibility as such:
2. When these conditions apply
2a) General

Except where clause 2c says otherwise, these conditions of carriage will apply to all flights we operate under the BA airline designator code and to any case where we have a legal liability to you in relation to your flight.

Seems that the buck is not being passed, but rather, the obligation was passed to BA.

Your signature says not to read into what didn't write but what I read is that the OP should not blame UA and therefore he's not entitled to any compensation from UA. Your logic is very confusing, to be honest.

Depending on the reason for the delays / cancellations you may be entitled to EU compensation.

I'm not familiar with all the ins and outs but we'd need exact details of the original flights (and departure times) and the new flights and departure times.

Sorry for the confusion.
We have nothing to complain about BA.
BA departed almost on time.
UA cancelled our flight then couldn't find an earlier flight to get to BRU.

Then you should be looking up the EU compensation rules, although keep in mind that UA will almost certainly try and take "unexpected causes" clause to get out of paying you anything.

Searching here or Google will find you plenty of information, including details of the recent court ruling that mechanical problems do not necessarily constitude "unexpected causes".

So the question becomes, when you accepted UA's offer to put you on a BA flight, at whatever time, did that cancel out UA's obligation to get you to your destination at a reasonable time? In other words, did accepting UA's offer to put you on BA modify the terms of the contract?

And could you have refused UA's offer to put you onto BA (not that there'd be any reason to do so) and how would that have affected things?

You can claim compensation as per the EC passenger rights. You can claim for the cancelled flight Euro 250 and also for the delay of the rebooked flight Euro 250 if delay was more tha 3 hours..take a look at www.euflyersrights.com it has a DIY or assistance program.

Your not getting it. UA placed you on a BA flight to get you to your destination. BA becomes responcable to get your to your desination, so again your beef is with BA no UA.

is that really correct - UA booked pax on BA flight which left and arrived as scheduled ... what can there be any beef about?

The Beef is that the OP wasnt coherent in what they posted in their 1st post.

I too after reading the 1st post thought the OP was FIMed over to BA to get between LHR & BRU and then the BA flight was some 4.5 hrs delayed in arriving into BRU.

Only later on did the OP come back and state that the BA flight pretty much left on time

OP PLEASE edit your 1st post so that everyone hence forth will understand that the BA flight wasnt delayed

Now it seems the UA flight was late into LHR and the 1st BA flight they were FIMed onto ended up getting them into BRU 4.5 hrs late due to UA very late arrival into LHR. If OP thats not what happened I give up as you arent that coherent in your posts as to what exactly happened , when it did and by whom

also sometimes someone will read a post and then click to reply before having read all the posts after that 1 and thusly only after posting might they read a follow-up post that might do a better job in explaining things, in that case Id hope any OP (including me when Im 1) will go back and edit their post/s that someway wasnt good in explaining the Details

If I'm reading things right, UA booked him onto a flight that had a scheduled arrival around 4.5 hours later than his original (canceled) flight. It doesn't matter if that flight was on BA or UA, but UA was responsible for the 4.5 hour late arrival due to the cancellation of the original flight, and thus his beef is most definitely with UA.

Exactly. ^