The purpose of this paper is to attempt to examine the relations between airworthiness and safety.

It seems to me that the problem of safety in aviation is fundamentally a problem of human behaviour. The human controlled aeroplane is mechanically extended man. To quote Sherrington

If we exclude the effect of the counter strategies of competition an accident is a measure of the incompleteness of this dominance.

Safety in the air in simple terms means a reduction in the number of accidents. There are many factors which influence air safety, some of which are being dealt with by other lecturers; for my part I propose to consider a vital one, namely, the human link in the mechanism of control of heavier-than-aircraft which, for all practical purposes, is the pilot. However much importance is placed, and rightly, on such factors as aircraft structure and performance, meteorological aids, ground traffic control, and the many other details which are concerned with an aircraft's safety, the ultimate factor in this, as in practically every form of transport, is almost always the human one.

Although there may be, and usually are, contributory causes leading up to an accident, subsequent enquiries frequently record an error of judgment on the part of the pilot as being the final precipitating factor.

Before I present my written paper I would like to refer to two aspects of my subject which have been omitted from the paper, icing and static discharge.

I have no records of icing being a direct cause of accidents but it is important to appreciate the effect that it has on a pilot when flying an aircraft which picks up a lot of ice which he knows he cannot get rid of when he wishes. I look forward to the time when there will be installed on aircraft a de-icing system which will enable a pilot to get rid of ice at the right time.

With the return of British civil aviation to normal operating conditions after the war it was found that several problems which had previously given little cause for concern had become acute. More especially, the increase in the volume of traffic, particularly under instrument flying conditions, together with certain indirect consequences of the greater sizes and weights of aircraft, had brought about greatly increased congestion around major airports, and there was, therefore, an urgent requirement for an effective system of close air traffic control to ensure the safety and rapid movement of the traffic.

The Ministry of Civil Aviation immediately gave much attention to this problem of air traffic control, but at once found itself in serious difficulties on account of lack of sufficiently precise knowledge of the traffic and the traffic pattern. The then Controller of Technical and. Operational Services, Sir Conrad Collier, realised that the obtaining of the necessary data concerning air traffic control and other matters of technical interest was essentially a matter of operational research, and in 1947 a small operational research section was established which began work in the autumn of that year.

The Design of test frames of all types owes a great deal to the pioneer work of the Structures Department, Royal Aircraft Establishment. This particular frame contains some novel features and has been subjected to some unusual overall calibration tests, particularly in relation to the entirely automatic and centralised control gear.

The choice of apparatus for testing large scale structural components may be influenced by many factors. In the present case, the choice of a test frame rather than other types of equipment was governed by the following considerations.

In an industrial establishment it is essential that test equipment should be put to maximum use. Unlike a central testing establishment such as the R.A.E., major strength tests are relatively infrequent and therefore the equipment should also be suitable for as much as possible of the development and research testing which cannot be undertaken on standard material testing machines.

In multi-wheel undercarriages the application of the brakes not only affects the total load on the undercarriage, due to transference of some load to the nose wheel, but there is also a local transference between the wheels of the bogie itself. This note calculates these loads and gives two methods of preventing excessive overload of the tyres.