Originally Posted by
DYKWIA
There have been a couple of reports of doing double upgrades on board. I think mrtdxb may have been one of them.
In my case I had already upgraded from Y to J with miles beforehand and then successfully upgraded from J to F as soon as I boarded. Twice to date with no issues at all. I have not yet gone for the big one - a double upgrade on board - and kind of hope that I never need to as at my advanced age I would not want to fly Economy unless there was no other option at all.