Automated aids, computer assistance and other forms of advancing technology are gradually changing the human involvement in many tasks, so that the primary roles of man are to monitor, verify, manage resources and respond to emergencies, rather than to participate actively and continuously in the control loop. Many of the terms traditionally employed to designate or describe jobs are retained throughout this process although they are no longer apposite, and they can give a misleading impression of the nature of the residual human roles and of the skills required to fulfil them. In many respects an aircraft pilot may no longer actually fly his aircraft for much of the time, but monitor equipment that flies it automatically. A nominal supervisor may remain in many environments where revised human roles and facilities mean that effective supervision is impracticable. An assistant may not in fact be able to offer true assistance because he has no facilities to share any of the tasks, do parts of them, or assume temporary responsibility for them. The future navigator may not need to be able to navigate in the traditional sense.