Originally Posted by
anabolism
..
The few times I have attempted to upgrade BA flights on RTWs, I was told (by AA when I tried to use AA miles, and by BA when I tried to use Avios) that it wasn't possible to upgrade on xONEx fares. I'm not saying the agents who told me this were right and FTers are wrong, just that the situation and any actual rules do not seem to be clear.
From the BA Trade Support website:
Provided there is redemptions availability and they hold a valid ticket that has been made in the eligible classes on 125 paper, customers can spend their Avios* to upgrade themselves into the next cabin for either 1 flight within the booking or the entire journey:
https://www.britishairways.com/en-nl...es-using-avios
To upgrade using avios (UuA) the flights you are upgraded must be on BA ticket stock as a condition precedent. This applies to any ticket, rtw or otherwise. If that condition is met then there are a number of other conditions that may or may not apply.