Pick away JD.
The Fernando de Noronha theory was Takata's explanation for his drift analysis. Takata assumed the current was constant from the time of impact. As such he plotted the crash site to 1.9 N - a log way south of the last known position. I guess he could only explain the plane being that far south as being due to controlled flight - and I presume he therefore suggested a diversion to Fernando de Noronha as a possible explanation for this.
I buy Takata's drift analysis (in part). However I doubt that the plane was as far south as 1.9 N. There is no logical reason for it to be that far south, and if they did reverse course there should be some corroborating evidence to support this. Therefore the current was not constant from the time of impact. It was fairly constant (speed and direction) from day 6 when the bodies were first discovered. But it was doing something else for the first 5 days - who knows what.
The real point is that the bodies were not drifting in accordance with the current charts when they were discovered. At 3.5 N on the 6th, these charts suggest the current was to the NE. The bodies were drifting slightly west of north.
Therefore, the best thing to do with these charts is to ignore them. And keep an open mind as to where the bodies were drifting over the first 6 days. Don't attempt retrospective drift analysis based on charts which could only be tested once (days 6-10) and were shown to be inaccurate.
I have long forgotten whatever I ever knew about 2nd order curves. However that does not matter here. We have no idea what the currents were really doing. I am sure some datum buoys were thrown out by the FAB. But if they were not thrown out in the right area then they are pretty meaningless also.
Life-jackets? I can accept that not everyone would get a jacket on. I find it strange that no one got one on - these are the bodies that would most likely be found, and I feel that if 50 recovered bodies did not have a jacket on then probably no one put one on.
No Mayday or other call?
Very importantly, cabin crew seats were not used. The cabin crew are all taught the importance of using their seats - rear facing with shoulder as well as lap belts.
Any one of these factors? Shrug shoulders. However putting these 3 things together, it is hard to escape the conclusion that things went from routine to totally out of control very quickly. So nope, I don't buy the controlled flight to the south theory. There is nothing at all to support it.
So what are we left with. At some point soon after last known point, the most likely sequence of events appears to be a pitot blockage leading to stall and loss of control and a spin. Probably recovery of spin at some point (if we accept the BEA analysis of the impact). Then a rapid descent with some forward motion. The plane could have been pointing in any direction at that time, and so possibly a few miles were covered during the descent. My guess is that this was to the south. Based on 2 factors:
i) we have not found it and we have looked in most other directions
ii) a few miles SE does incorporate the pollution spot (that is pretty thin however).
Any unsecured cabin crew would likely have been incapacitated by this stage and hence would not have got to their seats. Any restrained pax that were still conscious were probably beyond doing anything as organised as putting on a jacket. And the pilots are probably not going to transmit anything at that point either.