Moderator, Iberia Airlines, Airport Lounges, and Ambassador, British Airways Executive Club
Join Date: Feb 2010
Programs: BA Lifetime Gold; Flying Blue Life Platinum; LH Sen.; Hilton Diamond; Kemal Kebabs Prized Customer
Posts: 63,830
On AA I doubt you would get access, the front desk has a list of flights that they expect to see, and the JAL flights won't be on this list.
For BA at T5? Well you may be able to blag your way in, but in theory it is for BA and AA operated flight, not the rest of oneworld.
Welcome to Flyertalk hpsc, I hope that we will see more of you here, and best wishes for Boxing Day.