Why Air Traffic Control (1970): The operations of the National Air Traffic Control Service within the context of an increasing density of commercial, military and private air traffic. The film explains their division of airspace into lower, middle and upper, and designation of directed flight corridors for commercial airlines. It also demonstrates 'Approach Control', the localised area of control that is specific to a single airfield. Illustrated throughout by aircraft including the Vickers Viscount, the Concorde prototype, the Vulcan and Harrier.