Originally Posted by Furby

You need to see availability on AA for 12.5K or less for economy, and 25K or less for business to book on BA with Avios. Many AA awards are priced above that (sometimes by just 500 miles more) and those cannot be booked with Avios. Also, BA are not great at finding connecting AA flights, sometimes you have to search segment by segment and if successful call in to BA to book as one ticket. But, the situation is that many AA award flights cannot be booked on BA anymore. The amount charged by AA changes dynamically, it’s not unusual to change amounts within the same day, so check frequently and grab something immediately it’s available because it may not be available several hours later at the same rate. They decrease the amount as well as increase it, it’s very random. I have snagged last minute award tickets using Avios and then been offered cash the next day to be bumped from the same flight.