Beardy, there was never an attempt to predict future mental health problems. Those who displayed problems while under stress were weeded out because airline pilots are supposed to be able to handle highly stressful events calmly and efficiently. The young man referred to appears to have had an "event" when placed in a stressful situation. Stress is often the trigger and those who cope well under stress are unlikely to have a triggered event. Hardly archaic beliefs going on here.