Terrible news for BA frequent flyers if miles accruals and award redemptions are going to be allowed for AAdvantage members on transatlantic flights. BA premium classes will be packed with AAmericans who all things being equal will prefer to fly BA because of its superior product. Most AAmericans I know would prefer to fly BA in J or F but never do because of the current mileage accrual/redemption rules. Expect scarce premium award availability and far fewer I class deals if this is allowed to happen.