Murder-Suicides by Pilots Are Vexing Airlines as Deaths Mount - Bloomberg
It is really a good piece of journalism by bloomberg, a wide variety of factors are described in an unemotional, fact-driven way. The main problem is also described: how to tackle the problem? All ideas so far have other much bigger disadvantages, as properly described in the article.
May be there is just a residual risk we have to live with? At least until someone really comes up with a convincing solution. So far I haven't seen one.