The problem is that the very opening of "proceedings" means that "guilt" of a person or persons is a possibility. In this case all the witnesses to the crash itself are unfortunately no longer with us, and so cannot defend themselves, and meanwhile the tabloid press look to dig up every morsel that might back up the sensational potential outcome, whilst no doubt ignoring any mitigating evidence that might get in the way of a good story. If the co-pilot had survived the accident (let's imagine he's in a coma, one of several survivors) then what chance would he now have of a fair trial? None.
Let's not forget that a single "rogue" pilot is actually about the best outcome for the aircraft manufacturer and the airline in terms of the money each will have to spend to be seen to "correct" the situation. I'm not saying that there is any kind of cover-up here - I have great respect for Lufthansa and the French authorities and in many ways they are doing outstanding work. However, once you start such a cannon ball of a conclusion rolling it is almost impossible to stop it, even if significant doubts later arise.
This is the danger of the early "obvious" conclusion. Presumably the French prosecutor is aware of the implications on future flight safety and the unions' concerns, yet it has chosen to ignore them in favour of getting the "truth" out there after only a few days. Let's hope future lives will not be lost because of the lack of trust and thus lack of honesty engendered in what might be perceived as a "flawed" investigation system that could result in a pilot being a suspect in deliberately causing the injury of his/her passengers because of mental health issues years ago.
The "gains" in eliminating such incredibly rare events may well be swamped by the loss of life resulting from the loss of confidence of pilots in the integrity of the system that thay will be given a fair trial and hence their subsequent lack of co-operation with any investigation ...
