At an open meeting of the Technical Committee held in London on 26 April 1978, with Dr. J. F. KEMP in the Chair, the broad question was discussed of the relative benefits of carrying navigational devices in an aircraft as against installing them on the ground. Introducing the discussion Captain B. J. CALVERT of British Airways suggested that for landing in very poor visibility there was no either-or choice; any system must be cooperative and involve the combination of air and ground components. The question was where to strike the balance. With the redevelopment of a fog-dispersal device (for one was used in World War II) it seemed possible to re-examine the question. The fact that there were now many years of airline experience of low visibility landings made the discussion even more appropriate.