This horrific event has aroused strong emotions all round, and very different emotions, from anger to pity to blame, and for myself confusion. I cannot understand what drove this young man to do what he did - I expect none of us can.
Mental illness is impossible to understand and categorise. Whatever caused him to crack up at that moment had been simmering inside for a very long time. From the photos I've seen it looked as if he tried to cope with his illness himself. He must have felt he had nowhere to turn. It doesn't excuse his behaviour, that is beyond excuse, but he must have been in a very dark place.
Those of us who have been there, on had a close family member or friends who have taken their own lives, or are slowly destroying themselves, recognise how impossible it is to know what's going on in their world.
What's done is done. Soon the world will move on but these families, and the parents and friends of the co-pilot, will never forget and life will never be the same for them again.