The greatly increased cost of fuel has intensified the need for the manufacturer to increase operating efficiency in the aerodynamic, structural and propulsion fields. These aspects have already been highly refined and further improvements will be more and more difficult to realise. However, DOC is also equally affected by equipment and crew costs and this paper therefore attempts to examine the potential for improvements to the flight deck that will determine the most cost-effective combination of crew and equipment required for the safe operation of relatively large transport aircraft.

In the past, design effort has, very logically, been concentrated on those fields that could be shown to give an obvious economic return, and since investment in new instrumentation, flight deck workload analysis and system automation showed less tangible results than increases in speed, range, payload, etc, there was no great incentive to allocate money and effort to “human engineering”.

Modern aircraft, both combat and civil, are representative of the most complex “man-machine” devices ever produced and they have now been developed to the stage where, relatively speaking, little more will be achieved by the normal evolutionary processes. Increasing attention is, therefore, now being paid to new configurations, new materials and new uses of technologies such as safe automatic controls in an attempt to break through the present limits of performance, safety and cost.

One of the most rapidly advancing technologies at the present time is microelectronics and its particular application in miniature digital computers. Professor Gosling of the University of Bath recently described microelectronics as a “technology which makes negligible demands on materials and energy and yet is already changing the rules for future social evolution by making possible intelligent machines, which achieve biological orders of complexity at trivial cost”.

It is indeed a great honour and a particularly pleasing experience for me to have been invited to give the 18th Lanchester Memorial Lecture. Pleasing because it enables me to recall before such a distinguished audience, one of Lanchester's outstanding achievements in the field of aircraft stability, his phugoid theory. This slow oscillation problem has often been neglected but its implications can be vital as the Vulcan crash in 1956 emphasises, and the development of STOL with high lift has forced designers to turn again to a serious consideration of the phugoid as I will show presently in the first part of this lecture.

Veneration can often bestow an undeserved degree of respectability upon stories which have come down to us from the past. Some of these stories even acquire the status of legends if they are repeated with sufficient regularity, and, like the “laws” which tend to limit the vision of the scientist, these legends can restrict the retrospection of the historian. Aviation has its share of such tales, and it is one of these which now needs to be re-examined in the light of several new pieces of evidence.

The central character of this story is that great eccentric Noel Pemberton Billing, and the aeroplane with which we are concerned is the P.B.9, a neat little biplane scout which appeared at the outbreak of the First World War.

Probabilism is the 16th century philosophical doctrine that certainty is unattainable but that belief and action must be governed by probability. As long as the existence, interpretation or application of a law remains doubtful, one may follow his own inclination, on the ground that a doubtful law cannot impose a certain obligation. But the subject “probabilistic design” embraces the idea of conceiving or planning of a thing so as to be fit for its purpose, more likely than not, but with less than absolute certainty. The designed “thing” is to be reliable. The lay meaning of “reliable” is trustworthy, predictable and good, and carries an implication that at successive points in time the “thing” will or could be somehow exposed to its purposed use and will successfully fit its purpose every time or most times.