Thanks Guy Betsy

I don't know about it being THAT late in the day though..the ba gets into sfo at 1:50 and the aa departs at 3:45.

I couldn't find any information about minimum connecting times on the sfo website but in the cx timetable it says that minimum connecting times for internation - domestic flights at sfo is 1:45. So I would presume that it is a valid connection and that if I miss the connection then they would put me on the next available flight even if there is no availability in my particular booking class??
If I do happen to miss the connection then do I have to take the next aa flight, which leaves more than 6 hours later or will they book me on an earlier flight on another airline??

Thanks