I claim to have no expert knowledge on landing aids, but the Aeronautical Research Laboratories in Australia have done some work in this field. We were invited, or encouraged, to take up this branch of work by a Meeting of the Commonwealth Advisory Aeronautical Research Council in Australia in 1955, when the difficulties of the landing phase and the need for some form of aid for the pilot were emphasised.

I need say nothing about the difficulties of the pilot: they have already been amply emphasised. An early example of operational research in this field was an investigation made by Professor Collar in 1941 on the problem of the dark night take-off, when the pilot tends to mistake forward acceleration for a climb in the absence of sufficient external visual cues.