from 2000' - the a/c would start to be reconfigured from a low drag, 180kt config to landing Flap.. Not normally a problem with the automatics in... the 'training' F/O in the RHS - possibly a little behind the drag curve - will be calling for the flap changes which the Cpt will be selecting.. at the same time no doubt - approach will be instructing a change over to Tower requiring frequency tuning (heads in)- so quite a high workload even for the trainer (who's also supposed to be watching what his trainee is doing !)
The 'faulty' RAD ALT problem at 2000' sends the A/T into 'retard' but could easily go un-noticed as T/Ls would be at idle anyway, as speed reducing.. (Not sure when the 'nuisance' GPWS alerts came - but these would just add to the confusion.)
F/O possibly becoming more and more maxed out - poor scan rate, probably concentrating on looking out for first visual clues of RWY (i remember being there !) - Should have his hand on T/Ls - but hasn't - not picked up by busy T/Cpt..
As final Flap (30?) has been reached - thrust levers fail to advance but this isn't immediately picked up by the F/O. Cpt possibly distracted by contacting tower - maybe heads in dialing up the ground freq - (i can never remember which one, so maybe he has to look at the chart!)
Speed has quickly decayed but still IMC so the increase in attitude not so obvious - the lack of noise possibly masked by GPWS noise.. as the stick shaker goes off Cpt takes control and advances T/Ls - (A/P disengaged but forgets to take the A/T out - ok we can all do it ok in the Sim, but you only have to read how many G/As are poorly handled these days.. & this is after a stick shaker ) Uses both hands on control column due to the high forces involved.. 'inexplicably' - the thrust levers 'retard' again - which none of us would expect.. before he realises it's too late....
Some posters have correctly stated that there are certian situations when training must simply stop - but these can creep up on you very quickly... it's easy to blame the crew for lack of monitoring, and in fairness they should have done better - one does wonder what the third crew member especially was doing - if, in deed he was there as a 'safety pilot'..