Why did I get upgraded on JAL with AA Codeshare?
 

Hi guys, just wondering if someone may be able to shed light on whether its standard practice or not? I am executive plat, so oneworld emerald. I had the following routing CGK-NRT-DFW of which, the CGK-NRT flight was on japan airlines codeshare. My NRT-DFW SWU cleared a while back, but I totally expected to be in economy for the japan airlines portion. However, upon checking in, I was assigned a business class seat on the new skysuites! talk about a great surprise. however, the flight was only half empty and I am wondering why they upgraded me? Is it safe to assume that I might get some sort of complimentary upgrade again in the future for regional routes? thanks

I've been similarly upgraded on ANA a number of times, but in those cases the flights were full, so they likely needed the seats in economy for non-status passengers.

In your case I think it had nothing to do with your SWU and was tied to your OWE status. Why they upgraded when not full in Y, who knows but it does happen sometimes.