This accident really remains a mystery.
I have to say I (along with some others) was strongly in favour of a search close to LKP. The really strange thing about it is now that they found it close to LKP I'm somehow at a loss as to why it is so close to LKP ?!
It would be really interesting to know where it is exactly, but if it is closer than 5nm from LKP, even a 'simple' spin scenario rather wouldn't do it.
From the Pulkovo crash we have a pretty good idea how long it can take from FL400 down to SL in a flat spin.
Looking at the Wing Loading of AF447 being ~580kg/m^2 compared to ~400kg/m^2 for the Pulkovo Tu154 we can assume that the vertical velocity /Rate of Descent in a flat spin should be a bit higher.
So the time for spinning from Fl400 all the way down should be below 200s, maybe rather 180s. (back then I roughly calculated terminal velocity of the A330 @210t as being in the order of magnitude of 140kts which seems reasonable with the ~120kts of the TU154 at Pulkovo))
Now let's assume the overall event took between 4,5 to 5 minutes. that would mean 90s - 120s before entry into the spin. if we decelerate from 480kts to 350kts the plane would travel between 10 and 15 minutes in that time span before entry into the spin. And even then there is still momentum to continue forward travel for some distance.
Looking at these assumptions I tend to assume there was some kind of course reversal, maybe unvoluntarily due to e.g. a massive wing drop ending up in opposite direction after recovery, maybe followed by a second upset this time losing it for good.
Unfortunately it really takes some creativity to get the plane to a point that close to LKP after a 5 minute struggle. Occam's razor seems to be off for vacation.
The other possibility would be that the speed was shed much quicker initially. With a full pull-up manouver it should be possible to decellerate to 350kts in maybe 30s. That would cover ~5nm. But then the remaining time of 4 - 4,5 minutes would require some form of recovery before the final plunge. All this w/o effectively traveling any distance.
None of the scenarios is really convincing. However, somehow it must have happened ????!