AA charges 57.5 k plus $733 for LAX -LHR for an award on BA metal.

AS charges 70k miles plus $966.

i understand the mileage difference but why such a big copay difference? Is the BA carrier surcharge negotiated carrier by carrier?

It’s done on point of sale. Go look up the price in CX and you will see once you convert from HKD.

Also you should look at ex-EU vs. ex-US, it will be instructive on pricing.

Either way it's ridiculous. I've actually found BA coach fares that were less than the copay to use AS miles.

The actual YQ charge (from ITA Matrix) for that flight is $1,025, while AA only charges $700 for it. Does that mean AA has a better deal with BA than AS, or AA absorbs a portion of the charge? I'd bet it's the former.

I wouldn't assume YQ/YR charged on revenue fares necessarily has any relevance to carrier-imposed surcharges on award bookings. It would seem likely it's negotiated on carrier-by-carrier basis (does anyone really expect AA to eat costs here?). YQ/YR on revenue fares can go up and down (usually up) and can actually also vary by season/fare class on same routes (note differences below).

Is it even clear that the ticketing carrier pays any of the YQ it collectsto BA? I seem to recall that when LA was part of oneworld, LA award tickets for travel on BA had no carrier surcharges.

AA and BA are part of a revenue sharing joint venture, so any TATL revenue AA collects is shared with BA and vice versa (I believe on a basis pro-rated based on each airline�s TATL capacity, but not sure about the details). AS is not part of that joint venture.

There was a recent article on one mile at a time blog in January ("How Much Do Award Tickets Cost Airlines? You Might Be Surprised") with some insider info on how the accounting works on award redemptions between airlines. It is mentioned that payment rates are negotiated between airlines individually and are charged on a segment basis.

For revenue fares, the airlines that are part of JV partnerhips do revenue sharing on overall income between carriers on routes that are covered by partnership. This might influence award redemptions charges between them, but I wouldn't make too many assumptions.

I wasn't suggesting that the full YQ/YR charges on revenue tickets are passed on to a partner's FFP, but they do serve as references and/or caps. I agree that the cost of redemption (YQ/YR included) is negotiated between the operating carrier and the partner's FFP.
That's what I think. AA seems to have a better deal with BA than AS. OTOH, AA could have marked up these charges but chooses not to. Few of us want to pay such a large charge for an award in the first place.

So how is it that CX (not part of the TATL JV) has considerably lower fees on a BA TATL award booked using CX Asiamiles ex-USA than either AA or AS?

(note that this doesn't apply the same way ex-UK/EU, the YR on award tickets goes down quite a lot)

I would also suggest comparing round trip pricing if you book:

USA-UK/EU-USA
UK/EU-USA-UK/EU

For instance, the first screenshot is booked as the return on an AMS-PDX-AMS round trip. The second as a one way, same date, flights and class of service PDX-AMS.

Whoa, that's interesting. I was under the impression that one-ways were never higher priced than what they'd be under a r/t. Thanks!

Yeah, not so much for BA.

The trick seems to be use CX to get to the UK/EU on BA (there's really a dramatic difference on YR, like all in CX tickets are on the order of $300-400 for J/F, that's a significant price break on AA or AS) and then use BA's differential pricing for ex-USA vs. ex-UK/EU YR advantageously.

Since CX has some good partnerships for transferrable points (AMEX, Citi, Capital One, Bilt) it's a viable strategy. Or you could just load up your Avios account and do it that way I suppose (and take advantage of wider availability of J on Avios). BA J/F pricing on Avios can be very brutal though...

can you just book the roundtrip for better cash-copy pricing, and once ticketed, cancel the return (get the miles refunded since Alaska allows that). Or would alaska start asking for more money to drop the return segment?

The mileage amounts on AS don't differ on one-ways vs. roundtrips, but the carrier-imposed fees on partner award flights can differ based on trip origin.

Delta does something similar and has assymmetric carrier-imposed fees on awards on partner metal depending on origin. For example, UK origin DL business class awards on partner metal currently have a $475 carrier-imposed fee, but if the partner metal on UK-US flight is part of roundtrip booking originating in US, it's only $30 for business class ($10 for economy). There's no carrier-imposed fee on DL partner metal award flights on one-ways from the US. One interesting effect is that although the carrier-imposed fees are small on ex-US roundtrip bookings involving partner metal on return, they do trigger roughly $45 in US international departure/arrival taxes on awards as they are no longer considered "zero fare" award tickets where those taxes get waived.

The return is the NA->EU segment that you�re saving money on? You would have no advantage to just booking EU->NA one way. AS doesn�t charge extra booking EU-USA-EU the same way it does booking NA-EU-NA.

Again, if you are doing regular trips you would be better off using another program to get to Europe then do round trips STARTING there.