Originally Posted by
bocastephen
Not exactly accurate - I've been able to upgrade BR flights many times where I class was not available.
Under the Star Alliance upgrade flow? If you are using other means, then yes. But I have never heard the Star Alliance upgrade to be anything other than award space. You can eg. use UA plus points on LH and NH (and potentially others I don't know about), that is not based on award space being available, but it is also not the Star Alliance upgrade flow.