To: John Farley
It takes a heap of flying for a given fleet to accumulate 1 Billion flying hours. In the mean time systems will fail and airplanes will crash. The only thing that protects highly automated aircraft is a high level of redundancy and even with redundancy failures can occur that were never even conceived of during the analytical phase.
Several years ago two 767s lost all electrical power. Granted the 767 is not highly automated but they reflect the state of the art for those days. Another 767 was lost when a thrust reverser deployed in flight. Boeing only performed a computer analysis and determined if it happened the aircraft could be safely flown. The deployment was the result of a designer not really assessing his design for possible failure modes. As the saying goes “Sh!t happens and when it happens on a commercial airliner it draws a lot of attention.
