I have never understood what problem self-driving cars is trying to solve. I can, on the other hand, see that it could be more desirable to have self flying planes. But to even think that self flying = issue free and non crashable planes is beyond naive. Personally I believe that the best is to let humans do what they do best, and let computers do what they are good at. Without trying to force one into the other's shoes. (Computers has shoes, don't they?)