Having spent his career planning, operating, and controlling power systems, Knight (Imperial College of Science, Technology, and Medicine, London) offers advice on dealing with a system under short-term instabilities, usually caused by extreme weather conditions, which he points out are predicted to become increasingly more common. He explains disturbance and system failure, different forms of disturbance, what severity should be covered by normal protection and control rather than emergency facilities, planning and operating measures to minimize the impact, restoring normal conditions, training staff, environmental factors, costs and benefits of emergency control, and future developments. He also reviews some major disturbances around the world.