What was co-pilot thinking as he sent plane into descent?

andreas-lubitz-germanwings-crash
The horrifying turn of events in the Germanwings air disaster has left airline authorities speechless. The president of Lufthansa, owner of the discount airline, said he was stunned by the idea that a co-pilot would purposely crash an aircraft full of passengers. Nonetheless, evidence from the cockpit recorder suggests this is exactly what happened. But there is nothing in the background of Andrea Lubitz, 28, to support this insane turn in his behaviour. It will no doubt be part of the investigation to learn as much about this young man’s psychiatric state as possible.