This account of the practical steps taken by British Airways to provide the Concorde with a reliable navigation capability which meets the needs of supersonic flight on commercial routes covers: the features of supersonic flight which lead to new navigation requirements, the social and political constraints on supersonic flight, and the need for the crew both to be well informed of the progress of the flight and prepared for the possibility of return to subsonic flight. These factors have led to special techniques for route planning, flight planning, documentation (including charts), and accuracy of navigation.

All these techniques are based on a navigation system constructed from standard components, but meeting the aircraft's needs for accuracy and automation.

Commander Haines examines the more stringent navigational requirements of fishing vessels, reviews the instruments in use, both radio and acoustic, and discusses the significance of a number of navigational factors, such as speed over the ground when trawling and the avoidance of obstacles on the sea-bed. The paper was presented in London on 14 May 1975 with the President, G. E. Beck in the Chair.

The accelerated growth of aircraft operations is causing severe congestion problems at major airports throughout the world and adding heavy burdens on Air Traffic Control which result in traffic delays. Area navigation is regarded as a solution to this problem and a means of more efficient and safe utilization of airspace, both en route and in the terminal area. It is important to evaluate the navigation accuracy of RNAV systems in the Japanese airspace before introducing the concept of Area Navigation technique.

Circumstances of collision. Over a fourteen-year period more than 80 per cent of all collisions in the Dover Strait occurred in reduced visibility. The majority of the ships concerned were carrying radar, so a possible inference is that the information available from this source is less effective than direct vision in successfully resolving close-quarters situations. The introduction of the Imco recommended routing scheme, the support measures mounted from the two sides of the Channel and sustained improvements in navigation have together led to a significant reduction in the number of collisions in poor visibility. However the risks, though reduced, remain higher than in good visibility.

The circumstances leading to collision are very rarely known reliably or in any detail, but such facts as are known can be helpful if treated with caution. Reference 1 gives details of manoeuvres preceding 47 collisions, nearly all in fog, where helm orders were noted in crew reports (Table 1). About three-quarters of these collisions (and of collisions as a whole) occurred when ships were on opposing courses, as defined by their ports of call.

Among the many problems arising from the exploitation of North Sea oil is that of finding practicable landfalls for the proposed pipelines. The oil companies have been confronted with some of the most difficult landfalls yet experienced where the requirement for precise positioning has been paramount. This paper, which was presented at a meeting of the Institute held at the Southampton School of Navigation on 23 October 1975, outlines the problems encountered and the methods used to overcome them.

In this note I wish to enter however belatedly into the discussion of error distributions in navigation (cf. Anderson and Anderson and Ellis). Not being a navigator my arguments will be purely statistical, but I hope that they will throw some light on the problem, which seems to be an important one.

Hampton and Mills have commented that large errors occur more frequently than is predicted by gaussian behaviour; and Anderson remarks that in practice the ‘skirts’ of the empirical distribution are commonly hitched high over the estimated gaussian tails. The conclusion drawn is that navigational errors follow a distribution closer to the two-sided negative exponential than to the normal though, instead of peaking to a sharp point at the centre, the empirical distributions seem to have rounded heads.

This paper, which was presented at a meeting of the Merseyside Branch of the Institute on 24 February 1976, is a sequel to Captain Emden's paper on the setting up of the Dover Strait Information Service which was published in the April 1975 issue of this Journal.

It will be recalled that in 1971 the Marine Division of the Department of Trade set in motion a number of activities designed to improve the safety of navigation in the Dover Strait. It is convenient to group these activities under three headings: scientific studies of marine traffic, surveillance and the Information Service, and future developments. It is the purpose of this paper to give an up-to-date report on each of these subjects.

The device described, which is in prototype form, accepts ship's speed from the Harrier electronic log and heading data from the Halcyon transmitting compass and continuously displays the north–south and east–west components of the water distance traversed from a starting position. It is a development of the Hadrian distance-offtrack computer which, with the Harrier log, has been described in a previous article published in this Journal.

The Sensors. Harrier is a through-hull impeller-type electronic log which records distance run in steps of 0·01 n.m. on an electromagnetic counter and indicates speed on a suitably calibrated milliammeter. Halcyon is a recent development, being a two-axis fluxgate transmitting compass which senses the Earth's magnetic field directly, thus avoiding the major problems associated with the use of pivoted magnetic systems in fast power vessels. The two rectilinear fluxgates are mutually perpendicular and are pendulously mounted with their axes in the horizontal plane. Viscous damping prevents their oscillating when subjected to vibration and shock. The outputs of the compass circuits are two d.c. analog signals which represent in magnitude and sign, the sine and cosine of the heading angle respectively.

Dr. Freiesleben, an Honorary Member of this Institute, discusses the geometry of ellipses and hyperbolae on the sphere. These are the curves which correspond to position lines based on the constant sum or difference of distances from two fixed points. Originally applied to astronomical position lines they now have a wider application to electronic fixing systems of global coverage like Omega.

A simple method is described for estimating the angle of misalignment of a two-component electromagnetic log, using the covariance properties of the measured components when a ship is steered in a constant cross wind at a number of different speeds. It is shown that, with the present accuracy of radar fixing, allowing for misalignment has a very small effect on the determination of sensitivities for an absolute calibration. However the effect of misalignment is important when cross-calibrating the athwartships components of two electromagnetic logs.

Air Traffic Control is part of the process by which aircraft ‘go about their ways’ and thus can fairly be regarded as a branch of navigation. Because of the existence of centralised control organizations, and because much of the total flight time is spent in the vicinity of system ‘hubs’, air traffic interacts with itself in very complex ways. For this reason the traffic as a whole behaves in a manner that could not easily be predicted from an inspection of the system elements. Thus there can be said to be a ‘system’ problem, where by a system is meant, not the specific hardware but the abstract elements which determine the essential overall performance. These abstractions would, for example, be common to a computer simulation of an ATC system and to its real-life counterpart. The present paper will attempt to discuss, at this ‘system’ level of abstraction, the problems facing air traffic control and the principles on which the system design should be based.

The International Association of Institutes of Navigation (IAIN) was represented by the Secretary-General (M. W. Richey) at the eighteenth session of Imco's Sub-Committee on Safety of Navigation from 22–26 March, under the Chairmanship of Captain W. S. G. Morrison (Canada), and the thirty-fourth session of the Maritime Safety Committee (MSC) from 3–7 May, under the Chairmanship of Dr. L. Spinelli (Italy).

In accordance with the recommendations of the Sub-Committee on Safety of Navigation the MSC approved:

1. Amendments to the traffic separation scheme and deep-water route in the Sandettiearea.

2. An amended traffic separation scheme off the Casquets.

3. A traffic separation scheme in the Gulf of Suez.

4. Amendments to the separation schemes off Delaware Bay and the approaches to New York.

Dr. Jan Wereszczynski, a member of this Institute, describes the little known Polish contribution to the mapping of eastern Europe at a time when interest in maps of the known world had been stimulated by the rediscovery and publication of Ptolemy's great work on Geography, written in the second century AD and forgotten during the Middle Ages.

The history of the cartographical development of the Baltic and Black Sea coasts reveals a significant contribution from Polish cartographers in the sixteenth and seventeenth centuries. The ‘father of Polish cartography’, and one of the most famous scientists of his day, was Bernard Wapowski (1450–1535) who published two maps of Sarmatia. One covers the northern part of the Balkan peninsula, a large part of the Grand Duchy of Lithuania, the Crimean Khanate and part of the Grand Duchy of Moscow. The other covers the country north of a line from Toruri to Novgorod. It should be emphasized that Wapowski's geographical coordinates are of outstanding accuracy, most of them, especially the latitudes, being based on his own astronomical observations.

The rapid developments of mini-computer technology and the introduction of integrated navigational electronic equipment in ships calls for a reappraisal of bridge design as a matter of urgency. Several research projects have been carried out in recent years and all have concluded that ‘a completely fresh outlook is required rather than work on existing designs and on methods which are regarded as both accepted and acceptable’. Shipowners and shipbuilders need to understand the requirements of the men who will be responsible for the safe handling and navigation of the ship and to choose between stagnant inefficiency and economical gain through proficiency. The standard central command-post layout design should comprise flexible units adaptable to every type of merchant ship, except of course such specialized vessels as oil rigs.

It is natural that present attitudes towards safety at sea and collision avoidance should reflect a justifiable preoccupation with electronics in meeting the exigencies of marine traffic congestion and collision hazards. Despite the frequency with which marine casualties occur during darkness and in conditions of poor visibility there is a tendency to minimize the positive, if modest, contribution of efficient and distinctive ships' navigation lights towards safety at sea in these circumstances.

Most authorities are agreed that detailed plotting is an essential part of a ship's radar collision-avoidance system, and teaching on the subject includes the calm intellectual detachment of the radar simulator; with First and Second Officers respectively to plot the data and evaluate the developing situation, decide upon the appropriate action and initiate the conn. In conflict with this ideal executive bridge manning concept is the increasing tendency towards automation and resultant crew reduction, to the point where in an increasing number of vessels (in particular the ever increasing number of specialized supply vessels in the offshore oil industry) spare capacity no longer exists to permit the separation of bridge functions such as lookout (Rule 29), radar observer, radar plotter and anti-collision conning. The dictates of low manning, long hours and arduous and often dangerous work on low freeboard, heaving sea-swept decks, all combine in such vessels to restrict bridge manning to a single navigating officer—as a rule on a six-hour shift—overseeing the gyro-steering, reading out and plotting from the position fixing system, operating the radios, keeping a weather eye on the various bridge-mounted engine gauges, observing the radar and, when necessary, overriding the gyro steering to manœuvre the ship manually in any collision-potential situation. Radar plotting is seldom undertaken in this class of vessel, there being a limit even to the accomplishments of the one-man-band.

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.

Following a general discussion on the effect of sea states on vessels at a meeting of the Technical Committee, held in London on 7 January 1976, those taking part were invited to submit written contributions, a selection of which is printed below.

P. H. Tanner (Glasgow University): It is a matter of experience for most small craft users that the steepest seas encountered in open waters are those that originate from the bow wave systems of passing ships. It is a matter of observation that these bow waves are of great persistence.

With the ever increasing information rates characteristic of modern electronic systems it is not surprising that display technology is one of the most vigorous fields of current research. A wide variety of phenomena is being exploited in order to produce displays suitable for a diversity of applications. This paper, which was presented at a meeting of the Institute in London on 17 December 1975, with Captain B. J. Calverb in the Chair, reviews recent developments in both emissive and passive displays, emphasizing the advantages of alternative types for particular applications.

Man's knowledge of the world in which he lives is steadily increasing and, compounded with a rapidly increasing capacity for communication, this leads to a need for new means of displaying the available information. The development of computers further increases this requirement since they make large quantities of information quickly accessible. It is to be expected that in many situations, where formerly the printed page or spoken word would at best have been the only practical possibilities, the advantages offered by modern electronic displays will increasingly be appreciated. In both civil and military applications it is clear for example that much information transmitted at present by letter could be better sent telegraphically, once suitably convenient displays are available; the need for ‘hard copy’ can be met where required. Considerable savings in time and convenience, not to mention paper, could clearly be made.