Originally Posted by
jerry a. laska
The BA information (can only upgrade on BA ticket stock - 125)is still correct and not stale.
http://www.flyertalk.com/forum/21739622-post595.html
I've definitely upgraded BA flights on AA stock, there just has to be some AA segments on there...AA even publish a table for upgrading BA flights.
As long as there's award space I've always just called AA and upgraded.
EDIT: I misread that you wanted to upgrade with Avios in which case this is correct, it would have to be on 125 stock, my apologies