It really is bizarre. If you recall dear old Meekal going on about some (possible) home-made unofficial R12 procedure (and like 411A getting terribly confused about circling...). The planned use of 'Nav' might hint at this but I cannot follow the PBD points inserted. Maybe someone could plot them? It seems finally that the a/c was roughly paralleling the downwind track but in the wrong place. How they finished up with 3000fpm down, IMC with terrain warnings I just cannot understand. It seems to me that the Captain had completely lost any idea of where he was or what he was doing and it really was classic 'time to take over' time.