A survey of approach and landing aids

Various all-weather approach aids for aircraft are reviewed briefly, with reference more to the facilities they provide and their operational limitations than to their detailed design and electronics. Certain aspects of the British Instrument Landing System are discussed and the principles and advantages of automatic I.L.S, approaches in bad weather are outlined. It is shown that there is little hope of extending, with safety, any system of blind-approach aid plus visual landing to operating limits lower than about 150 ft cloud base and 500 yd slant visibility. It is concluded that the next major step must be a completely blind landing without visual reference, and promising solutions to the problem are indicated.