A person that works in internet security claims that he was able to take over the flight control systems of a Boeing 737 while he was physically on the airplane as a passenger. The FBI is investigating this guy, but his story seems extremely unlikely especially since he claims to have done it multiple times on different flights.
Everyone has the potential to suffer from depression, even pilots. Should we permanently bar commercial pilots from flying if they have a history of depression? This is one potential way to try to avoid what happened on Germanwings flight 9525 where all evidence points to the co-pilot intentionally crashing the plane.