it would need a bit more forward travel past LKP to avoid considering the a/c dropped like a stone at an average AOD of 45 degrees. This means a turn (back) of some description, and most likely pilot input.
That just made me mindful of a time just north of the Pyrenees when I was trying to tell the guy on the ground that we had little idea of our position. We were on a 22min beacon-to-beacon leg, and 47 mins later we finally passed that beacon. For a lot of the time, our progress had a high vertical component - it was nothing short of chaotic for well over an hour, but there was never a time we turned intentionally off course.
If, as it seems is the case, this poor crew found themselves inside a vicious CB, only a second by second analysis of their exact position will throw much light on those terrible minutes. I'm not sure even the FDR will reveal that much detail as only inertial summing could reveal the details of the decent.
Is it hoped there will be that kind of detail in the FDRs?