I am deeply conscious of the privilege of giving this First Joint Lecture of the Royal Aeronautical Society and the Society of Licensed Aircraft Engineers and Technologists. I am delighted this has been initiated by our two bodies. Our close working together can only be to the benefit of aviation as a whole in this country. It is also another step in bringing closer together those concerned with research, development, and design with those of us concerned with maintenance. In these days of high costs of equipment and of labour, I am glad to say that maintenance is at last being recognised as requiring a much larger degree of attention at the initiation of projects than has been the case in the past. Moreover, it gives me particular pleasure that a Royal Air Force lecturer should be invited on this occasion because of the very close affiliation of the work of engineers in the Royal Air Force with that of the members of SLAET.

This half-day symposium was held at the Society on 4th November 1970. The proceedings were opened by the President, Air Commodore J. R. Morgan, OBE, FRAeS, who welcomed distinguished visitors from overseas and introduced the Chairman of the Symposium: Sir Eustace Roskill, a judge of the Queen's Bench Division and chairman of the commission to enquire into the siting of London's Third Airport.

Mr. A. W. G. Kean, principal Assistant Solicitor in the Department of Trade and Industry, was the first speaker; he outlined the background to current proposals for revision to the Warsaw Convention to be considered at a Diplomatic Conference in February 1971 in Guatemala.

Subsequent proceedings were divided into two main parts: Part I—in which European viewpoints were expressed; Part II—consisting of a selection of American viewpoints.

An important written contribution to the proceedings is a copy of official statistics gathered by the Civil Aeronautics Board for the purposes of the Diplomatic Conference and released to the Society by the US State Department which will be published, together with the Part II discussion, and the written contributions, in the March issue of the Journal.

I am to argue in favour of strict liability as against the carrier and to oppose the limitation of damages, arguments which I advance with some satisfaction since I happen also to believe them.

Strict liability is a doctrine more usually associated with the law of tort than the law of contract but as an injury resulting from an air crash is both contractual and tortious (and it even seems at one time to have been decided in America that the Warsaw Convention had itself created a cause of action), even if it be inelegant from a lawyer's point of view, I shall make no distinction between them. There are enough distinctions to be made on this topic without insisting on the lawyer's habit of mind.

The Legal Committee of the International Civil Aviation Organization met recently in Montreal and decided to recommend a modification of the Montreal Interim Agreement to provide for a novel rule of liability. The rule would make the carrier absolutely liable, regardless of whether the carrier was at fault. The only exception to the rule would be where the passenger or person claiming damages had himself caused or contributed to the accident. The limit of the air carrier's liability would be raised to $100 000.

I will attempt to outline not only the current state of the law of aviation, but to critically dissect those provisions of the proposed treaty which I believe to be incompatible with fundamental concepts of justice and equality, and violative of constitutional safeguards of the Constitution of the United States. Recognisably, some of these comments may be controversial, but it is hoped that they will provide luminosity concerning a complex subject and reduce polarisation of views.

My paper is concerned with Operational Assessment on Air-to-Air, Air-to-Ground and Naval Surface-to-Air Guided Weapons.

I will start by describing the strategy and tactics for the use of these weapons to provide the military environment against which operational assessment is carried out. I will then say something of the methods we use of measuring the effectiveness of weapon systems by taking a number of examples and illustrating some of the different approaches we have used in the past.

Operational research is an attitude of mind and a collection of techniques. Although the people who make up the engineering strength of a guided weapons firm find that attitude of mind congenial and commonly approach their problems predisposed to use the techniques, it is uncommon to encounter an OR group in any great strength.

This is perhaps because the grouping of people by techniques in such firms is more natural when those techniques bear a direct relation to the firm's products. Despite the fact that a substantial body of practitioners is not to be found in close association, practices which are recognisable as OR are to be found throughout the course of a project.

The problem of cut-outs in structures being analysed by the matrix force method is solved by Goodey by the method of undetermined multipliers. It can be shown that the final results are identical to those of ref. 2. In this note we demonstrate that the method of undetermined multipliers can also be used to incorporate modifications into a structure. This, in itself, is only of academic interest for a simple problem. However, it does give many advantages when dealing with more complex situations. The basic equations can be written down quite simply and the development of the subsequent matrix algebra follows the straightforward pattern for solving simultaneous equations. Also, where previous results can be used, this becomes apparent.

The elastic modulus of a honeycomb sandwich core under transverse compression should be simply (ρE/ρ0), where ρ is the density of the honeycomb, ρ0 that of the material of the honeycomb and E the Young's modulus of the material. However when honeycomb sandwiches are tested under compression between flat platens it is common experience that the deformations recorded are markedly greater than those predicted from the theoretical modulus. In order to throw light on this discrepancy comparative tests have been made on three samples, two of normal thicknesses, namely in and in, and the third 8 in thick.

In their earlier paper the first two authors have given a solution to the problem of bending of clamped skew plates. The solution was obtained using the eigenfunctions of a beam. They have shown in their discussion that their results agree with other investigators except Kennedy who has used Galerkin's method. It was surprising to note that though both the authors’ and Kennedy's methods converged well, the results did not agree for all the cases and the difference being maximum for the rhombic case. It was mentioned in the discussion that additional work was desirable to resolve the difference. Hence in this note results using a different approach have been presented both for clamped and simply supported isotropic skew plates subjected to uniformly distributed load and the results are compared with the available ones.

On 22nd October, 1969, a joint meeting was held between The Royal Aeronautical Society and the Institution of Electrical Engineers, at 4 Hamilton Place, London, W.l. The subject under discussion was methods for reducing the large numbers of wires used in present day aircraft.

Mr. Ruy de Barras—Sabena Airline, read a paper on new wiring techniques using flat strip wires. The paper was awe inspiringly entitled “System of Interface Matrix of Parallel Lines” (SIMPL), although the technique proved to be most simple.