The United States Maritime Administration recently published the results of a study, undertaken by the Norden Division of the United Aircraft Corporation, on automation and the operation of merchant ships. Mr. Clayton, the author of this important report, described the findings of this investigation, in so far as they affect navigation, to an Institute Meeting held in London on 16 November 1962. The paper, which is presented here, was written in association with Mr. Kurz of the U.S. Maritime Administration. It describes navigation systems for partially and fully automated vessels, and discusses the basic system requirements, accuracy and reliability criteria. A command philosophy for automated ships is developed, and finally a marine course computer, which is the first component of a partially automated navigating system already manufactured, is described. This is the first of several equipments being manufactured under contract to the Maritime Administration.

In early 1959 United Aircraft Corporation, led by its Norden Division as systems manager, undertook a company-sponsored study of the technical feasibility of operating merchant ships automatically. The results of this study were circulated throughout the industry. In April 1960 the Maritime Administration awarded a contract to Norden to study the economic and technical feasibility of automating merchant ships. The principal objective of the study was to develop a consistent series of planned, orderly, and reasonable steps towards completely automatic ship operation. The technical feasibility and economic advantage for each significant advance would be thoroughly established and then presented in a form suitable for selective application according to the particular requirements of individual ship operators.

The navigational aspects of the requirements for a medium altitude satellite communication system are discussed. Twelve satellites have to be injected into a circular equatorial orbit with very great precision. It is not practicable to navigate the launching vehicle accurately enough to obtain the correct orbit at first injection and the satellite itself has to be controlled and adjusted until finally it is correctly positioned with the right period.

The navigation of the third-stage rocket is discussed as this effects the limits of adjustment required for the satellite. Some error in period is necessary at injection in order to position the satellite correctly in orbit, in a reasonable time. A suitable tolerance on the period at injection is 3 minutes in 8 hours. This must be reduced, by fine adjustment of the satellite speed, to less than 30 milliseconds. Methods of measuring the orbital period to this accuracy are discussed.

When the 12 satellites are finally in orbit and equally spaced around the orbit they should remain for up to 5 years with the pattern substantially undisturbed.

This paper was presented at an Ordinary Meeting of the Institute held in London on 18 January.

The basis of navigation is the finding of present position and velocity so that the necessary action can be taken to guide the craft or vehicle to its destination.

Lucretius, in the century before Christ, was by no means the first wise man to ponder and seek to explain the apparent mystery in this biblical citation, and he is but one of a great company of ancients whose recorded sayings are a delight to all who love the sea. We shall come back to Lucretius.

A meeting of the Technical Committee was held on 9 January in London, at a session which was open to Members of the Institute and to various other people by invitation. From the Chair Wing Commander E. W. Anderson explained that the object of this kind of meeting was to enable the Institute to consider more or less informally matters which were in dispute and to give all Members an opportunity of attending these discussions. The subject under consideration had been discussed, sometimes with vehemence, at meetings, in private correspondence, and in The Journal but agreement among the contestants seemed no nearer. An exchange of views at a technical session might be fruitful. In this account of the discussion, written contributions not presented at the meeting have been included.

This paper, and the papers by Gérardin and Payne which follow, were presented at the meeting of the Deutsche Gesellschaft für Ortung und Navigation held in Dusseldorf 5–7 June 1962 and are printed with that body's kind permission. An account of the meeting was published in the last number of the Journal (16, 111).

The scientific engineering review of the U.S. Task Force on air traffic control, known as Project Beacon, was completed in the fall of 1961. In their report to the Administrator of the Federal Aviation Agency, the Task Force makes no claim for originality of most of the ideas and recommendations which were presented. Consequently, many of the problems resulting from the proposed plan of action have been previously discussed. However, the very positive and specific treatment of basic principles and the presentation of clear decisions produced considerable impact. The blurred picture created by less definitive approaches has been brought into better focus. The remaining problems are reduced in number, implementation efforts can be concentrated and the probability of success has been increased.

At the present time, radar is taking a more and more important part in air traffic control. That part is certainly going to develop even further in coming years, with the steady increase of traffic and the general use of jets on main airlines. Radar control has the advantage of presenting the controller with a clear picture of the position of each target, associated with an instantaneous view of the whole air situation. And, because radar information is renewed several times per minute, the situation displayed is always up-to-date. Unfortunately, that situation is rather anonymous. To make it usable, the targets observed have to be identified. In the first place, we have information about them from the flight plans; the identification of a particular aircraft then reduces to a choice between a few possible echoes only. A commonly used method is to send an order to the target to manoeuvre: the target obeying that order identifies itself by doing so. This method is simple, but not very quick. Moreover, the ordinary PPI unfortunately does not retain a memory of such an identification.

The continual increase in the complexity and performance of modern aircraft give rise to the need for improved accuracy and versatility in the electronic aids available to the crew. The system described is an example of digital computing techniques applied to the problems of air navigation. Navigation was chosen as a typical problem but the flexibility of the computer would allow it to be applied to other in-flight problems, such as the calculation of fuel and air data.

Dexan (Digital Experimental Airborne Navigator) is the outcome of some three years' work at the Applied Electronics Laboratories of the General Electric Company at Stanmore and the Royal Aircraft Establishment, Farnborough. The calculations performed by the computer to carry out a particular navigation process are shown schematically in Fig. 1.

Aircrew reports of turbulence at heights between 20,000 and 40,000 ft. are analysed to show geographical and seasonal variation in incidence of turbulence. It is found that there is generally a summer minimum of turbulence and an autumn or winter maximum.

Reports of the occurrence or non-occurrence of turbulence have been made for the flights of Comet 4B aircraft of British European Airways. Although the assessment of the turbulence was no more than subjective it was thought that the uniform nature of the aircraft, operating over a large number of flight sectors in the European and Mediterranean areas, and the fact that ‘nil’ returns were also made, could give useful indications of the geographical and seasonal variation of the incidence of the high-level turbulence. An analysis of the reports, made during a period of twelve months, is presented here.

It is well known that in low-frequency hyperbolic navigational systems the phase differences measured by the receiver do not correspond precisely to the hyperbolas on the plotting chart. This is largely because of variations in the terrain over which the waves are propagated. The system service area may be sampled so that the curve distortions can be ascertained at selected points. This article discusses how the whole service area can be calibrated, given a knowledge of the grid distortions at a sample of points. The mathematical treatment takes into account the correlation between the grid distortions at adjacent sampling points by using autocorrelation theory.

The degree to which fixing accuracy is improved by the proposed method of calibration is assessed against the background of an actual set of field measurements.

Mr. Sullivan is Head of the Applied Research Group of the Navigation and Guidance Laboratory at the Institute of Science and Technology. Dr. Porter is Assistant Professor of Electrical Engineering at The University of Michigan, and Head, Analytical Research Group of Navigation and Guidance Laboratory at the Institute of Science and Technology.

In low-frequency ground-wave navigation systems such as Loran-C and Decca, position information is determined from measurements of time and/or phase differences in signals received from several separately located transmitter stations. A pair of stations generates a family of hyperbolic lines which are the loci of points of constant time/phase difference. Two station pairs provide a grid of hyperbolas. By measurement of the time/phase difference between the signals from two transmitters, the receiver is located on a hyperbolic line. The same receiver is located on a second line by similar measurement which uses another pair of stations; the receiver is thus fixed specifically at the intersection of the two lines.

In the discussion which followed the papers on Hovercraft Navigation, Captain M. J. Edwards raised an important point. ‘If the hovercraft is the stand-on vessel, it may be impossible for a large slow-moving vessel to take avoiding action in the short period between sighting and collision.’ This implied that both were following the International Collision Regulations, and these cannot be altered (except by local authorities in ‘inland waters’) without international agreement and the attendant delay.

The problem of estimating equipment serviceability when the apparatus consistsof a large number of individual components (possibly with standby features) islikely to be of increased interest now that navigational thought is being concentratedquite as much on the design of instruments the navigator uses as on theproblems of finding position at sea or in the air. The resulting exercise in combiningprobabilities of component failure is a fairly straightforward one but inview of the accelerating interest in the matter (see, for example, Cluley's articlein this Journal, 15, 387) a brief systematic treatment might be of interest toworkers in these fields.

Whereas it is doubtless true that the two largest contributions to the errors of sights at sea are those referred to by Mr. Sadler in his Prefatory Note to Captain H. H. Shufeldt's paper on Precision Celestial Navigation Experiments, it cannot, I think, be gainsaid that the principal avoidable error in sights is due to faulty use of the sextant, especially in respect of collimation error.

The planetarium consists of an optical projector centrally situated under a dome. The viewers sit around the projector instrument in chairs designed to give a comfortable view over the whole interior. The instrument used by the writer is the Spitz A2, manufactured by Spitz Laboratories, Inc., Delaware, U.S.A. Seating is provided for 40 persons under a 20-ft. dome in the particular installation at the South African Nautical College General Botha, Gordon's Bay, Cape.

Some lessons and observations experienced during a series of radar simulator courses in the period of one year are listed below:

1. The practice of plotting is generally favoured by the students and they learn quickly how to determine which targets are of concern and should be plotted and which targets may be rejected. It has to be pointed out fairly often that recordings should be taken down in an orderly manner and that—besides the time, bearing and range of a target—the heading and speed (or log reading) of the observing vessel should be written down with each set of observations.

The Maritime Safety Committee of the Inter-Governmental Maritime Consultative Organization considered the Report of the Dover Strait Working Group set up by the British, French and German Institutes of Navigation, at its session which ended on 25 January. Members of the Safety Committee were, in general, in agreement with the recommendations of the Group that a system of routing should be established and that the navigational marks and other aids in the Strait should be improved. The Committee considered, however, that the report required further study by governments before definite views could be formed; account would also have to be taken of the result of the enquiry now being addressed to masters of ships by the International Chamber of Shipping through its members.