Originally Posted by
Airprox
If you want to upgrade using Avios then you must be both booked on the BA prime flight number, and NOT the AA codeshare, AND ticketed on 125 stock. If you booked via a TA then you can have only BA codes flights and metal and will still be able to upgrade using Avios, if you book directly with BA then you can include other carriers for connections.
I think the poster who asked the question about whether the fare is upgradeable is part of AAdvantage not BAEC, so the Avios may be a moot point for their situation.