1. Who turned off transponder. Remember, even the whole plane lost power, the transponders would not.
2. Perth, transponder never went off.
3. Low altitude fight in Radar detectable area but high in Radar undetectable area.
I agreed with the analysis that the autopilot system was disordered but the pilot did not know until last minutes too late to correct,-to contact the navigation control .
Similar situation could happen in GPS,some drivers followed the instruction without paying attention what GPS directed to the wrong destination such as deep sea,violent river,dangerous cliff ----not able to turn around because of downhill driving too difficult to stop and was killed.