Originally Posted by
43Inches
Except from the track indications there is no evidence to say they were commencing a turn, that's all pure speculation. (The curve at the end of the tracking is whilst the aircraft is in rapid descent).
I'll add that the plots indicate over 1 minute from the start of downwind to where things seem to have departed normal, a lot can happen in 1 minute of aviation, or nothing may have happened until the split second it departed controlled flight.
Does it make a big difference whether the pilot had actually commenced the turn or was merely preparing to turn (which clearly he was going by the drop in airspeed prior the point at which the turn was expected). Either way the point at which he was either commencing the turn or was about to do so, is where something went horribly wrong.