I am in favor of autonomous vehicles, but I am just as afraid as most humans of the loss of control with the third dimension (height). Humans pilots can react better than any known autonomous aircraft because their sense of preservation kicks in and they do all they can do to save their lives and their passengers, too. No autonomous vehicle has reached that level of conservation (read Issac Asimov's Laws of Robotics) so they have no "sense" of survival, and cannot respond the same way. The best they can do is to warn the passengers and send for help after the crashes.
Until they do, all aircraft needs a pilot. And most autonomous land vehicles still miss that "sense" and are risky to ride in. Only trains are less risky because they only move in one dimension on a limited track with no competition or risks of collisions, and as so are easier to manage and control by autonomous means. And as it has happened, train collisions are caused by human errors. So a combination of human "sense of preservation", excellent distance and speed sensors, and exact program execution will be the basic guides for autonomous vehicles, be them trains (one) cars (two) or planes (three dimensions).