Originally Posted by
loudnotes
You're mistaken. Just below the chart on the linked page, it reads:
"*Includes travel on codeshare flights marketed by American Airlines, British Airways and Iberia and operated by any of the three carriers."
Since a BA ticket must be issued on AA ticket stock to be upgradeable with AA miles to begin with and AA generally tickets these flights as codeshares, this is a distinction without a difference. If an upgrade were actually made available, AA just reissues the ticket as a BA prime flight.
In any case, what is not clear from AA's website and should really be made more explicit is that "BA W" != "AA W". When a customer goes to book a BA flight on aa.com, they are confusingly shown a fare code of "W" for premium economy and not told that this W is not the same as the BA W until wasting lots of time on the phone.
In the generic overview where it states that upgrades can be done on IB,AA and BA, there is an asterisk to the footnote regarding codeshares being eligible
In the specifics for
Economy-Premium Economy/business - there is no airline restrictiom, so upgrades permitted on IB,BA,AA Y class fares
Business-First - limited to AA J,D,R classes and BA J,D,D,R classes
and for
Premium Economy-Business - limited to BA W class only
From this, it seems pretty explicit that only BA marketed flights are eligible for upgrades to premium economy. Since the other 2 airlines do not currently offer a premium economy cabin, there isn't going to be a codeshare option
When AA starts offering premium economy on its flights, this table will need to be updated or will again be misleading
That converting an AA flight booking to a BA prime booking requires that the fare basis be one that converts over to W class on BA would be good information regarding the ability to deal with AA codeshares on BA, but doesn't seem necessary given the upgrade restriction being BA only