I came across this site just the other day
https://flightavailability.bcdtravel.com/OnlineInfo/EN/MnAvlForm_ver.aspx
It seems to show the availability of flights by booking class.
Presume this would be useful for determining the availability of upgrades for Elites - which I think are booking classes A and R??.
Has anyone used this and is it reliable do you think?

