This paper describes two methods by which lines of position may be obtained by observation of stars (in pairs) without the use of instrumental scale readings either for altitude or for azimuth. These lines of position represent arcs of great circles of the Earth. An instantaneous observation is proposed.

Great circles determined by star positions form, on the celestial sphere, a lattice which is not deformed by precession. Whether or not he be at rest relative to the rotating Earth, the observer's zenith traverses this lattice, which thus may serve in celestial navigation precisely as does a well-marked terrain in contact flying over land, or as do ranges and markers in coastal and harbour navigation. Observation of the zenith-transit of an element of this lattice is akin to the process of noting the moment when an aircraft crosses a coastal line or other visible terrestrial mark or to the recognition of when a vessel near shore is on a certain range. Observation of this type is as rapid as the navigator may be able to make it since it is the observation of the occurrence of an instantaneous situation.

The monograph which follows has been prepared for the Institute by Wing Commander E. W. Anderson and Mr. J. B. Parker, working closely with Mr. D. H. Sadler. It was designed primarily for publication in book form; however, the Council has decided to publish it in the Journal as well, so as to give it the best possible circulation among members. This arrangement has meant varying slightly the normal style of presentation in the Journal and apart from the title page and page numbers there is no difference between the published book and the pages which follow.

This is an abridged version of a paper which was presented at the NAVIGOS Seminar held in Cairo in October 1986. It describes the development of ship routeing in the Gulf of Suez since 197J. Dr Mokhtar is Director General of the Arab Maritime Transport Academy and Commodore Hussein is a consultant at the same Academy.

Dr. David Lewis, better known for his own remarkable feats of navigation, which include single-handed transatlantic passages, illuminates the background to various theories on early Polynesian navigation. Reviewing the evidence, which includes the wide dispersion of the Polynesians and their culture as well as methods of navigation and seamanship that were still practised at the period of European contact, Dr. Lewis concludes that they could determine both course and, in effect, latitude with sufficient accuracy to make a landfall within the area of a known island group, and so proceed to any intended destination.

The national SAR (search and rescue) objective is to prevent loss of life and injury through search and rescue alerting, responding and aiding activities. Specific objectives under the SAR Branch's five year R & D (research and development) plan are: reduction of search time, improvement of rescue technology, and systems integration. The project described in this paper falls under the first objective – reduction of search time.

This, and the following five papers, are a selection from those presented at the RIN91 Conference on Small Craft Navigation. The Conference was held at the Warsash Campus, Southampton, over the weekend 6–7 April 1991. Copies of thecomplete proceedings are available from the Director, price £30 to non-members and £20 to members (exc. postage and packing).

Shiphandling training simulators have come into use since 1967. Several such simulators, with differing technical characteristics and training goals, are now in use around the world. They are commonly used to familiarize already competent masters with new vessels, restricted water areas, or some form of standard bridge procedures. Acceptance of these simulators by highly experienced master trainees has been predominantly favourable. Ship radar simulators have been in use for a somewhat longer time. They are typically used for training entry level officers as well as experienced masters.

The aviation and nuclear reactor industries, with a greater experience of simulator technology and its training value, use simulators for both training and licensing. The military (e.g. Navy) and other government agencies (e.g. National Aeronautics and Space Administration) have extensively used simulators for training and qualification. It has been suggested (Schumacker, Madsen and Nicastro, 1972; IMCO Standards of Training and Watchkeeping Convention of 1978, Resolution 17) that simulators could be used for proficiency demonstration on the part of mariners. The US Port and Tanker Safety Act of 1978 requires standards for licence qualifications by use of simulators.

The United States Coast Guard and Maritime Administration have funded research into the role, technology, and effectiveness of ship-handling simulators. Depending partly on conclusions from this research, the Coast Guard will consider partial credit toward licences for successful completion of approved simulator training. The Maritime Administration may assist maritime training academies to design and procure simulator-based training systems.

This paper, having first reviewed briefly the operational characteristics of present radar displays, deals with a new technique for presenting the radar data whereby a large, bright, high-contrast radar picture can be produced on a flat plotting surface by projecting in sequence rapidly processed photographs of a PPI cathode-ray tube presentation. It is followed by an account, by the radar officer in S.S. Canberra, Mr. D. W. Sims, of the use of the system at sea.

Taking the dictionary meaning of society to be the civilized body of mankind – what are the relationships between society and the art or science of navigation? To define navigation itself I have used Wing Commander Anderson's definition of 1961 – ‘Navigation is the business of conducting a craft as it moves about its ways’.

In the mid-16th century the English began to expand their merchant and fighting navies to sail beyond the waters of north-west Europe. This necessitated mathematical navigation, charts, and written and illustrated sailing directions; all, from the 1580s, were embodied in the printed ‘waggoners’ of the Dutch and were used in translation by the English seamen.

In a previous contribution Professor E. G. R. Taylor has reviewed the development of the sea chart up to 1600, the year in which Edward Wright published his celebrated chart of the world on Mercator's projection. Wright's chart represents one of many minor incursions on the part of English cartographers into the field of nautical cartography, which at that time and for the next hundred years was dominated by the flourishing Dutch school of hydrography. It was not until the latter began to decline towards the end of the seventeenth century that the English cartographer really came into his own and began to produce charts to assist the navigator. Thus the evolution of the English nautical chart to its present state of development covers a relatively short span when measured against the whole background of maritime enterprise and endeavour.

The development over the past two hundred and fifty years has been sporadic rather than continuous, being characterized by sudden advances followed by long intervals of consolidation. Factors such as the needs of national defence, the invention of navigational instruments and advances in hydrographic surveying technique, have at various times acted as stimulants to chart evolution. Throughout the period under review responsibility for supplying the navigator with accurate charts has gradually passed from the many private publishing firms to a specially created national department.

This short paper discusses briefly the role of the current forms of bus priority used in the United Kingdom and how these strategies are incorporated within our urban traffic control systems.

The philosophy behind the SCOOT (Split, Cycle and Offset Optimization Technique) demand-responsive signal timings program is discussed, and the latest results from the bus priority trials carried out in London by the University of Southampton and London's Traffic Control Systems Unit (TCSU) are appraised. The system installed in London is compared with current dead reckoning vehicle location systems and the major differences highlighted.

It is of historical interest that it was written instructions in the form of periplus, rather than the paper chart, that are recorded as providing the first form of document to guide marine navigators. Therefore perhaps the wheel has turned full circle when it is the digital information rather than the video display that may provide the basic guidance for the navigation of ships in the future. In 1986, when IMO and IHO set out to develop standards and specifications, it was decided that the product to be specified would have to be equivalent to the paper chart. In so doing they were following the guidance of the SOLAS Convention, which requires charts to be carried in Chapter V Regulation 20 and, in Chapter 1 Regulation 5, permits Administrations to substitute equivalents. Regulation V/20 does not state that the charts to be carried be paper but, until recently, it has been assumed that this is what is meant. What is explicit, is that the charts to be carried are to be ‘adequate, up-to-date and necessary for the intended voyage’. Following this guidance, the IMO/IHO Harmonizing Group attempted to specify an electronic system that would be equivalent to a printed paper document. This proved to be no easy task. It was extremely difficult to claim that an electronic system can be as durable and as generally reliable as a sheet of paper. What if the power breaks down? This and many other questions had to be answered before the standards would satisfy the members of IMO.

Complex domestic airspace requires collision risk models and monitoring tools suitable for arbitrary aircraft trajectories. This paper presents a new mathematically based collision risk approach that extends the International Civil Aviation Organisation (ICAO) models to full aircraft encounters based on real trajectory data. A new continuous time intervention model is presented, along with a position uncertainty propagation model that better reflects aircraft behaviour and allows generalisation to all trajectories to eliminate degenerate cases. The proposed risk model is computationally efficient compared to the models it is based on and can be applied to large-scale trajectory data. The utility of the model is demonstrated through a series of case studies using real aircraft trajectories.

Collisions are one of the major accidents in the shipping industry, causing significant losses. In this work, a framework of marine collision risk identification strategy was developed to quantitatively analyse collision risks and provide an easy and convenient way to monitor traffic flow in relevant waters to mitigate the chances of collision. The model was verified by using automatic identification system data obtained from Tianjin Port. When compared to previous research, the proposed model can identify risks earlier and give people more time to analyse and take action. The results indicate that it also can provide a visual display to alert relevant personnel. The model can be used as a reference to identify potential collision risks or as an information source for future research.

The cocked hat problem is a difficult one and though Captain Cotter in a recent article, has gone a long way towards clarifying it, I believe that the fundamentals of the subject are more difficult than this article suggests. A brief treatment of these, together with an indication of how they may be applied in practice, may be worth while.

The star sensor field of view varies from several arc-minutes to 20 degrees, which directly determines the star vector orientation in the field of view (FOV). Although the relationship between star vector orientation in the FOV and attitude accuracy has been revealed, the influence mechanism of star vector orientation on the integrated navigation performance of a stellar inertial navigation system has not been analysed. In order to improve the integrated accuracy, the main errors such as star sensor installation error, gyro error and initial platform angle error should be estimated online. It is significant to study the influence mechanism of star vector orientation on estimation of the above errors. In this paper, the star sensor sensitivity and the geometry factor are defined to feature the difference between the optical axis direction and the non-optical axis direction. The formulised mechanism and quantification results between star vector orientation and integration attitude and error estimation accuracy are clearly given. Simulation and ground testing were conducted and it was found that the larger the star vector orientation along the optical axis, the better the error estimation accuracy. In contrast, the attitude accuracy is weakly sensitive to the orientation of the star vector in conditions of appropriate posture adjustment and star observation scheme. This conclusion can offer universal guidance for the design and evaluation of stellar inertial navigation systems with narrow field of view or large field of view star sensors.

To evaluate the aptness of a navigation system in a particular application, the designer needs to assess its performance over typical trajectories travelled by the vehicle itself. Moreover, he or she may be required to judge which components of the kinematics state may be better estimated (and which will not). The main contributions of this work are two novel and complementary performance measures that, in concert, allow for the assessment of a navigation system within the actual context of its application over specific trajectories. For a given on board instrumental configuration, the “excitability metric” permits the isolation of the contribution of the information conveyed by the vehicle's motion itself, while, the “sensability metric” measures the resultant overall quality of the kinematics state estimation. The same tools could help the designer planning appropriate vehicles manoeuvres in order to obtain a required precision for each estimated component. While emphasis is given on the mathematical justification of those metrics, their use is also illustrated with real flight data recorded from a sounding rocket.