bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aircraft Separation Assurance: Systems Design
Authors: Brooker Peter 
Published: November 2009

One of the major concerns in the operation of an air traffic system is the maintenance of adequate separation between aircraft. The assurance of an ‘acceptably low’ risk of collision is a crucial element in the system design. A number of factors need to be assessed in this process. What is the navigational performance of the aircraft in the system ? What are the possibilities for radar surveillance ? Are procedural arrangements together with position reporting a suitable mechanism? What difference would be made by collision avoidance or warning systems? Given that any combination of these or other factors has an implication on the minimum separation between aircraft, the level of safety ‘assured’ has to be balanced against the costs of the various alternatives which may present themselves.In planning for change the implications of new operating practices or devices have to be assessed carefully. For most changes the process is one of evolution rather than revolution, although collision avoidance devices may have more of the latter's characteristics. Even for ‘revolutionary’ changes it may be possible to model the new system. Thus the existing situation is studied and its characteristics observed, then there are hypotheses of the ways in which the change alters the mechanisms in the system and finally the likely effects on system performance through mathematical and computer (often fast-time simulation) modelling.
The Impact of Filtering on Sea and Air Operations
Authors: Pearson M. G. 
Published: November 2009

Estimation methods and filtering techniques are nowadays an integral part of any computer-based navigation system. The purpose of these techniques is to provide an estimate of required variables which is sufficiently accurate for real-time command and control purposes. Repeatability, which is important for so many applications, is deemed to be a by-product of the estimation process. For this requirement it is not strictly necessary for the process to be accurate, it is sufficient if it is only consistent; these are closely linked but one does not imply the other. The modern approach is to minimize the variance of the noisy observations or the sum of the squares of the residuals, and the methods available for doing this are increasingly refined. The impression given in the literature (and it is extensive) is that data processing can somehow compensate for the shortcomings of the basic sensors with respect to the operation being considered. Within certain limits this is true, but the real reason for the sudden surge of Kalman filtering for real-time on-line applications was the relative simplicity of the computational process. In a way, Kalman filtering has done for estimation theory what the Fast Fourier Transform has done for spectral analysis.The concept is simple enough to state. It consists of combining two independent estimates of a variable to form a weighted mean. One of these estimates is a forecast and the other is the current measurement.
Recent Surveys
Authors: de F. Browne R. 
Published: November 2009

Figure 1 shows the present state of surveys over the UK continental shelf. Out of an area of some 173 000 square miles contained within the British Fishery limits, 36 per cent has been surveyed by echo sounder, but not necessarily to a scale suitable for modern standards, and only surveys to full modern standards are sufficient to ensure safe navigation within r m of the seabed; a modern standard survey must be carried out using a modern echo-sounder and include a thorough sonar sweep. All hips of the Survey Flotilla are now fitted with a Kelvin Hughes MS48 echo sounder and an OAL side-scan sonar.New technology, such as the towed side-scan system, has enabled the surveyor to examine the whole of the sea bed between a regular pattern of sounding lines, spaced to ensure that the sonar beam from one line searches at least 50 m beyond the adjacent lines either side. This ensures that all wrecks, rocks and other obstructions on the sea bed which could be a danger to navigation are located, and subsequently closely examined for the least depth over them. Side-scan sonar is best operated at a speed of 5 or 6 knots, which means that the time taken to carry out a survey to full modern standards is far longer than twenty years ago, but during the last five years almost 8 per cent of the UK continental shelf has been fully surveyed to modern standards.Our Survey Flotilla comprises eleven vessels, four Ocean Survey Ships – Heda, Hecate, Herald and Hydra; four Coastal Survey Vessels – Bulldog, Beagle, Fox and Fawn; and three Inshore Survey Craft – Egeria, Enterprise and Echo.
The Use and Misuse of Charts
Authors: Morris R. O. 
Published: November 2009

We recognize that in the general line of trade (or, as we have had underlined again recently, of war) there will be places where ships have to go but where, with the best will in the world, we have not been able to provide adequate charting or even to recommend anyone else's chart as fit for use. The master and his owners, or the naval commanding officer and his operational authorities, have got to weigh the advantages of calling at that port, or using that route, against the danger to the ship and decide whether the gain justifies the risk.In 1973 we were astonished to hear that a foreign coaster on passage from a Bristol Channel port to Penzance had attempted to go between Godrevy Point, the north-eastern head of St Ives Bay, and Godrevy Island, some 2½ cables offshore, at low water. Fortunately for her, she was spotted by the local coastguard before she was irrevocably committed to the passage – and dissuaded. The largest scale chart of the area, Chart 1168, is on a scale of 1: 25000, and shows the passage as some ¾ inch across from high waterline, or less than half an inch between drying rock shelves. Admittedly it did show a narrow gap where the contour lines suggested that more than 5 m of water could be carried through the centre of the passage. The sailing directions state that the channel outside the island, between it and the outer shoals, should not be used without local knowledge. The inner passage is briefly mentioned but no instructions for passing through it are given.
Admiralty Sailing Directions
Authors: Pryor J. S. N. 
Published: November 2009

In 1970 a review of the Sailing Directions was undertaken to find out if they met the needs of the twentieth-century mariner. This review was based mainly on the response to a questionnaire promulgated by Notices to Mariners, to which some 900 replies were received. The general assessment was that considerable improvement was required in the port and pilotage information; a loose-leaf type of book, for ease in correction, was also suggested.The outcome of the review was the adoption of a new style, involving a stricter geographic sequence in dealing with the coastal features, more headings to divide up the text and proper names highlighted by the use of bold type at the principal mention. At the same time the international A4 size was adopted to provide a shorter line of print in two columns, and a better page size for graphics. Much pure description of the chart has been removed, but there is still rather too much repetition of detail which can already be seen from the chart.
The Work of the International Hydrographic Organisation
Authors: Ritchie G. S. 
Published: November 2009

Real Admiral Ritchie, who retired on 1 September 1982 after ten years as President of the Directing Committee of the International Hydrographic Bureau in Monaco, here looks at the work of the International Hydrographic Organisation, more particularly in those areas which are of direct interest to the navigator.In 1919 an International Hydrographic Conference was called in London at which representatives from the hydrographic services of twenty-four nations attended. After discussing at length cooperation in the fields of charting, Notices to Mariners, and the international exchange of hydrographic data, it was resolved to set up a permanent Bureau. The Conclusion to the Conference reads as follows:The International Hydrographic Bureau whose formation is here suggested fulfils, in our opinion, an imperative need. Assuring a close and permanent association between the National Hydrographic Services, it allows of the cooperation of the efforts of all maritime Powers to furnish navigators with more perfect and up-to-date nautical documents. Without limiting in any way the liberty and initiative which should be retained by the Offices of the countries concerned, the new organisation will avoid unnecessary effort and wasteful expenditure; it will create amongst the surveyors of the different countries a fruitful rivalry and personal relations which are frequently of great value. We are convinced that its rôle will constantly increase in the future, and that its establishment will tend greatly to advance the Science of Hydrography.The italics in the above statement are mine. These words still reflect the most important aim of the International Hydrographic Organisation over sixty years later.
A Tabular Method for Star-Sight Reduction
Authors: Nastro V. , Russo A. 
Published: November 2009

In a recent paper in this Journal the Director of the Royal Institute of Navigation describes some methods of navigating small vessels; he rightly includes classical astronomical navigation and describes some speedy and well-known methods of solution. In spite of the availability of such tables and mechanical devices the solution is not within everybody's reach because nautical ephemerides are always necessary; convenient tables are the Sight Redaction Tables for Air Navigation (A.P. 3270) from which the elements for tracing out the lines of position through the intercept method can easily be extracted. The simpler tables here proposed present the following advantages:(i) the ephemeris is not required(ii) the observed sextant altitude need not be corrected for refraction and dip.
Random Air Traffic Generation for Computer Models
Authors: Goodwin J. L. , Ford R. L. 
Published: November 2009

Methods of generating random air traffic are described for two- and three-dimensional computer models used in a study of the problem of managing off-route traffic. Edge effects which influence the estimation of conflicts taking place near the boundaries of such models are explained and quantified.The applications of computer models in air traffic management studies are many and varied. References 1 and 2 describe some of these for which the appropriate model required the generation of randomly distributed aircraft following straight-line flight paths at constant speeds. Such behaviour can be a plausible representation of that of off-route air traffic for many purposes and the main objective of this paper is to describe methods for generating random traffic of this nature, that is traffic outside airways, terminal control areas and aerodrome control zones.
Weather Routing of Ships for the Northern Oceans
Authors: Motte R. 
Published: November 2009

Time and space scales are compared for selected speeds of ships in the North Atlantic and North Pacific oceans. Viability of westbound passages on some northern great circle routes is discussed.There would be no problem in precisely weather routing a vessel across an ocean if it were possible to forecast with total accuracy the actual sea state existing for the duration of a voyage. All mariners are well aware that such an ideal circumstance is not as yet possible. Depending upon the general synoptic situation existing for the period, it is fair to make the assumption that the actual accuracy of a weather forecast deteriorates as time progresses.
An Inquiry into North Sea Navigation
Authors: Ligthart V. H. M. 
Published: November 2009

Some results are here described of research carried out in the Netherlands with regard to marine traffic problems on the Dutch part of the continental shelf with emphasis on the preliminary results of the ‘Nautical Questionnaire North Sea’.The North Sea is a busy and interesting area, often presenting a challenge to the professional and amateur mariner, and to government bodies who have to see that people operating there do so in a responsible and safe manner. Figs 1 and 2 give an impression of the various types of activities on the Dutch continental shelf and of the collision and grounding positions of vessels in the North Sea over the period 1973–7. To reconcile the claims of all operations has become increasingly difficult as offshore activities have multiplied.
Vessel Traffic Management Systems: Some Considerations
Authors: Wepster A. 
Published: November 2009

When planning the replacement of an existing shore-based radar advice chain, which may have admirably served the port area under consideration for the past fifteen or twenty years, a number of basic elements have to be reviewed. The review and the ensuing process of analysis should be steps towards the adoption of a basic philosophy for the eventual development of a replacement system; this is necessary to judge requirements in relation to the many possible solutions, ranging from a simple shore-based radar advice service to sophisticated vessel traffic management systems. Elements for consideration include:(i) The area to be served, present and future.(ii) The traffic pattern, present and future.(iii) The technology available or under development.(iv) The other operational and administrative services available to shipping.(v) The quality of manning and manning scales.(vi) The economics of the shipping industry.(vii) The cost of the new system.(viii) The distribution of this cost over shipping and the community in general.(ix) Legal aspects.Besides these factual considerations and their analysis we should develop a philosophy regarding the aims of the system, which could be an improvement in port operation efficiency, in traffic safety, or in vessel turn-around time. The realization of these aims will probably result in economic benefits both for the port and for shipping and these will have to be weighed when investigating the distribution of system cost over shipping and the community in general.
Lord Kelvin and His Compass
Authors: May W. E. 
Published: November 2009

It is now more than thirty years since Commander W. E. May, R.N. (formerly of the Admiralty Compass Observatory), drafted this hitherto unpublished paper, recording his opinions based on a study of documents made available to him in 1947 by Messrs Kelvin, Bottomley and Baird. The documents referred to in the paper are:The Thomson v. Moore case as presented to the House of Lords in the Thomson v. Moore case (Patent Design and Trade Mark Cases, Vol. VII, No. 36.)The case of Thomson v. Hughes (Patent Design and Trade Mark Cases, Vol. VII, Nos. 9 and 22.)Report of Proof of case of Kelvin v. Whyte Thomson &. Co.Bound volume of patent specifications referred to in the last named.It is a curious habit of editors and publishers to invite well-known persons to write articles on subjects outside their normal orbit. Thus in 1874 Sir William Thomson was invited to write for Good Words an article on the mariner's compass. He took up the task and soon realized that he did not know enough of the subject to complete the article. He then began to study the compass and the final part of the article was published in 1879. Such is one of Lord Kelvin's explanations of how he came to interest himself. In 1885, in an affidavit for the Moore case, he said that he took up the study of the compass in 1871, whilst elsewhere he said that it was the necessity of writing for the Royal Society an obituary notice on Archibald Smith, who died in 1872, which first turned his attention to compasses.
The Admiralty Compass Observatory
Authors: Fanning A. E. 
Published: November 2009

The paper by Captain Cotter on Edward Johnson and the early history of ship's magnetism published in the September Journal sets the scene for the birth, in 1842, of the Compass Department of the Admiralty. Commander Fanning, a former Deputy Director of the Admiralty Compass Observatory, as it later became, here relates its subsequent history. The paper was presented to an Ordinary Meeting of the Institute held in London on 19 December 1979 with Dr J. F. Kemp in the Chair.This paper traces the fortunes and development of a small department, one of the oldest Admiralty technical departments, from its early struggles with the magnetic compass, through many vicissitudes, economies, defence cuts, wars, intrigues, take-overs and even human frailties. We shall see how technical advances have led to ever more demanding requirements and I hope to show how, by meeting each new challenge, there has emerged the lively, forward-looking organization that today is still responsible for ‘everything that matters’ in navigation equipment, as it was at its inception in 1842.
A Statistical Study of Factors Affecting Navigation Decision-making
Authors: Holmes J. D. 
Published: November 2009

This study consists of an investigation of the point at which ships' masters make decisions to avoid collisions, with regard to the time and distance separation from the other ship. The objective of the study is to find out what factors influence them to make their decisions to manoeuvre at this point rather than at any other; this involves the examination of various factors which could be relevant to the decision-making process, such as the speeds of the two ships, the relative bearing of the other ship, and the length of sea experience of the navigator.Several computer simulation models for marine traffic systems have been built but various subjective assumptions have had to be made about the criteria on which a decision to make a collision avoidance manoeuvre is based. This study represents the first systematic investigation of the statistical relationships among the factors affecting these criteria.
A Computer Simulation of Marine Traffic Using Domains and Arenas
Authors: Davis P. V. , Dove M. J. , Stockel C. T. 
Published: November 2009

This paper outlines the concept of a domain and an evasion area, called an arena, around a ship which are then applied to produce a computer model of ship behaviour. The arena determines when a ship takes avoiding action, as does the land arena which reacts with a discrete series of coastal points to prevent the ship running aground.The increase in the number and size of ships has resulted in the introduction of traffic routing schemes and the need to understand ship behaviour more thoroughly. The concept of ‘the effective area around a ship which a navigator would like to keep clear with respect to other ships and stationary objects’ has been used by various authors including Goodwin, Fujii and Lewison with varying names such as domain, collision diameters and encounter area. There has been no fixed shape for these areas. Some are circular, others elliptical, while Goodwin's has three segments each with its own portion of a circle. By developing the theory of the domain, it was hoped to be able to produce a model of traffic behaviour which could be used to simulate traffic flows, or specific incidents, in order to study them more fully.
On the 95 per cent Probability Circle of a Vessel's Position-II
Authors: Hiraiwa T. 
Published: November 2009

For a circular contour, which is one of the methods for indicating an error boundary, the author has studied the conditions for the probability of a ship's position (fixed by two position lines) lying within a 95 per cent circle by probability integration. In this case, the coefficient in the equation to indicate the radius is a function of an intersecting angle and an accuracy ratio between two position lines. The author has examined several accuracy ratios and applied the system to the error boundary of a ship's position fixed by three equally accurate position lines. However, as interpolation involves both angle of cut and accuracy ratio, the process is somewhat troublesome.In this paper it is shown that the accuracy contour for a fix is an ellipse, whether the accuracies of the position lines are the same or not, and a method is developed to replace an error ellipse for two position lines of unequal accuracy with an ellipse formed by two equal-accuracy position lines. The method is extended to three position lines of unequal accuracy. It then becomes possible to indicate an error boundary by a 95 per cent probability circle.
The Use of Transponders at Sea
Authors: Jones K. D. 
Published: November 2009

The two papers which follow (Jones and Ratcliffe) were presented in the course of a seminar sponsored jointly by the Institute with the Nautical Institute and held at the City of London Polytechnic on 13 December 1979. The purpose was to examine the usefulness of transponders for marine purposes. Seven papers were presented and these may be obtained at £7.50 (£5 for Members) from the Nautical Institute.The term transponder is usually interpreted by practising mariners as the simple inband swept frequency device, called Racon, with which those mariners are most familiar. It is this concept which largely colours the mariner's views on the topic, and is perhaps the reason for the obvious reluctance to accept expanding use of transponders which is apparent in the marine industry. Their personal recollected experiences of the clutter caused by Racon and the possible problems that could result from proliferation of such beacons give justifiable cause for this hesitancy.
A Sun-compass for Swinging Ship
Authors: Nagel T. J. 
Published: November 2009

A tedious problem which confronts many a yachtsman is determining the deviation of his magnetic compass. He can hardly justify the expensive services of a professional compass adjuster, so this necessary but difficult operation must be carried out by himself. Should he decide to use bearings of shore objects when swinging ship he is faced with the difficulty of observing these bearings on his compass. A small-boat compass is hardly likely to come equipped with azimuth mirror and sight vanes. The alternative equipment for taking the bearings is a pelorus, but the expense of this instrument could hardly be justified for such rare and intermittent use.The favourite way out of the difficulty appears to be to use a hand bearing compass. This method suffers from two disadvantages in particular:(i) The hand bearing compass should be situated in precisely the same position as the main compass if it is to reproduce the latter's readings precisely. Not only is this impossible to achieve in practice – the nearest they can be brought together is side by side – but when brought close together their mutual magnetic reaction can produce errors of an unknown amount.(ii) The use of bearings to shore objects naturally entails being offshore. Stationary small boats are notoriously unstable observation platforms and even a light chop would make it impossible to read the main compass with the accuracy necessary for a good deviation card.