The problem of collision avoidance at sea would be an important one even if accidents were rare, but the evidence suggests that they are much more common than one might expect. In the eight years leading up to May 1963 there were 60 collisions in the English Channel area and in the following eight years the number increased to 94. With the development of navigational aids such as radar one might have hoped for a decrease. The suggestion that the increase is quite likely attributable to the possession of radar is ironic indeed. It would appear that having the use of this ‘safety’ equipment allows the mariner to take greater risks, but that the risks which are in fact taken are greater than the equipment allows. We would do better to go back to fog horns alone. Even if over-confidence is not the only factor responsible for the increase in accidents, it does, nevertheless, illustrate the importance of the psychological variable in any man–machine system.

Collisions at sea, however, are not simply due to errors in a man–machine system, It is, of course, the hardware that actually collides, but the cause of the interaction lies in the decisions and indecisions of the two human agents controlling the vessels. It is essentially a social encounter. It is for this reason that the work initiated by Captain Kemp is greatly to be welcomed.

Civil aviation authorities have a requirement for the application of devices which are capable of determining the geometric height of aircraft above flight level 290 with a high degree of precision. These devices, called height monitoring units (HMUS), should pave the way for a safe and expeditious introduction of reduced vertical separation of 1000 ft above flight level 290.

In this paper the design philosophy as well as the prototype development of such a device, which is called the dual-synchronized autonomous monitoring system (DAMS), are outlined. This device operates fully independently of any airborne equipment such as secondary surveillance radar transponders.

The configuration basically consists of two standard marine radars with both axes of revolution situated in a horizontal plane. With this configuration it is possible to determine the trajectory of an aircraft and, in particular, the geometrical height above ground level within typical radar slant range coverage of some 18 km. The basic application of this equipment will be in the field of height monitoring of aircraft targets in environments with reduced vertical separation standards of 1000 ft above flight level 290, but a wider application of this concept is foreseen for local precision tracking of aircraft targets.

The Royal Navy employs naval architects to design its ships and a number of establishments exist to advise the Director General, Ships, on various specialist subjects connected with warship design. The Admiralty Experiment Works at Haslar, near Gosport, (AEW) which was founded in 1872 by the father of modern naval architecture hydrodynamics, William Froude, advises the Director General on all aspects connected with hydrodynamics. Froude's activities and those of his son R. E. Froude, who succeeded him as Superintendent, covered a wide field but the study of resistance and propulsion in calm water occupied most of their energies. William Froude was indeed responsible for the first real understanding of the mechanism of ship resistance and was able to demonstrate that the resistance of a ship could be accurately predicted from model experiment results.

The following is an abbreviated version of the 29th Haldane Memorial Lecture given by Sir Frederick Brundrett in the University of London Senate House on 7 March 1963. Sir Frederick is Scientific Adviser to the Civil Service Commission.

For many generations mariners have been taught the law of storms and the rules for avoiding their centres. This paper describes some of the practical difficulties of avoiding hurricanes in the south-west Pacific area, and the failure of meteorologists to appreciate the dangers and difficulties of the mariners.

About half the tropical storms observed conform roughly to the parabolic track of the law of storms. They form about 10° South of the equator during the north-west monsoon, (from December to April), and travel west-south-west, south-west and south-south-west as they gather strength and speed to a maximum; at 20° South they pause, recurve through south-south-east and south-east as they diminish in force and pass out of our consideration at 30° South.

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.

Three textual works by Olaus Magnus (1490–1557) hold the key to the ‘compass’ on his invented island of Hvitsark, shown on his 1539 Carta marina. Although Olaus had little general understanding of the magnetic compass or of navigation in the Far North, he evidently did not intend the navigational device he drew on Hvitsark to represent a magnetic compass, but a sundial. His muddled ideas about the relationship between 12 wind-directions and direction-finding at sea by means of such a dial appear related to his second-hand information about a gnomonic navigational device used by the medieval Norse.

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.

In his detailed and valuable account of the history of the Log (this Journal, 9, 70) Commander Waters is surely at fault as regards the part he ascribes to the Gresham Professor, Gunter. This eminent mathematician delighted in designing instruments with engraved scales, and at first issued the customary Description and Use in Latin, a sufficient indication that he wrote only for fellow scholars. Importuned probably by the instrument-makers, he later published English versions of the tracts (in 1623), and among the numerous ‘uses’ included a couple of chapters on those for navigational purposes.

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.

The basis of all recommended methods for obtaining position by using celestial bodies is the known altitude of the celestial body being observed. Accordingly, it is necessary to have a sextant, classic or with an artificial horizon, or some other device that can measure altitude. However, there is a way to obtain position using astronomical navigation without determining the altitude of a celestial body, and this method will be analysed in this paper. The introduced method requires only precise measurement of the azimuth, and is based on determining two positions close to the dead reckoning position and lying on the isoazimuthal curve, i.e. a curve of the same great circle azimuths of a celestial body. Furthermore, the model assumes that a part of this curve, between the selected positions, can be replaced by a straight line. Special attention will be given to the analysis of errors of the line of position for various azimuth errors and various dead reckoning (assumed) positions. It will also be shown how a modern Electronic Chart Display and Information System (ECDIS) can help in approximate position determination, knowing only the azimuths of celestial bodies.

This study is a brief report of the only re-sailing of Columbus' 1492–1493 Voyage following the data in his log in a scientifically controlled research voyage by a professional and experienced global and ocean navigator. The study is follow-on to the article: “The Controversial Skill of Columbus as a Navigator: An Enduring Historical Enigma,” published in The Journal of Navigation (2009) Vol. 62, 417–4251.

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.

In the July Journal (14, 362) Klerk and Steensma describe a new and ingenious method of radar plotting. The following comment, sent in at the invitation of the editor of the Journal, follows closely my remarks on a similar article in the Dutch review De Zee (December 1960).

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.

D. H. Lewis, in his article ‘Ara Moana: Stars of the Sea Road’ in the July 1964 issue of the Journal of the Institute of Navigation (pp. 278–88), speculates on how the Polynesians could have navigated to known distant destinations, but does not explain how the knowledge of die distant destinations on which he relies for his theories was gained by the supposed navigators. Before anybody can navigate to somewhere, someone must first have gone there and come back. Lewis does not tell us how the Polynesians gained their knowledge of the existence, location and size of New Zealand and Hawaii, and of the currents on these courses, on their outward voyages of discovery, and then used this knowledge to get home again. His statement that ‘it seems probable that the Polynesians steered by horizon stars until the zenith star showed that they had reached the right latitude, and then turned east or west’, obviously has no application to voyages of discovery which by definition were made without prior knowledge of the existence, latitude or size of the objectives. The alternative supposition that the discoverers were able to keep account of their courses from bearings on stars which were reputedly aligned with the destinations and the home islands overlooks the fact that such star bearings gave no clue whatever to longitudinal displacement. There was no practicable method whereby the discoverers could have known the longitudinal relationships of their discoveries and their home islands.

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.

In a car navigation system the conventional information used to guide drivers in selecting their driving routes typically considers only one criterion, usually the Shortest Distance Path (SDP). However, drivers may apply multiple criteria to decide their driving routes. In this paper, possible route selection criteria together with a Multi Objective Path Optimisation (MOPO) model and algorithms for solving the MOPO problem are proposed. Three types of decision criteria were used to present the characteristics of the proposed model. They relate to the cumulative SDP, passed intersections (Least Node Path – LNP) and number of turns (Minimum Turn Path – MTP). A two-step technique which incorporates shortest path algorithms for solving the MOPO problem was tested. To demonstrate the advantage that the MOPO model provides drivers to assist in route selection, several empirical studies were conducted using two real road networks with different roadway types. With the aid of a Geographic Information System (GIS), drivers can easily and quickly obtain the optimal paths of the MOPO problem, despite the fact that these paths are highly complex and difficult to solve manually.