A survey of visual guidance aids for aircraft.

The paper first summarizes the visual information required to enable the pilot of an aircraft to close and hold a desired course. It then describes various visual aids which have been proposed or used, identifying three principal types, namely 'geometric' (patterns and indicators), 'photometric' (colour and brightness assessment or matching) and 'flashing' (including sequential flashing to produce a running sign). Composite devices using more than one of these types are included, but a distinction is drawn between these devices and those which are, for example, coloured or flashed merely to increase their conspicuity. 'Stop' indicators for aircraft parking, though not strictly tracking aids, are also included. [ABSTRACT FROM PUBLISHER]