Contours of constant probability density have been calculated for Loran systems in different service areas, and from these some ‘Loran navigational charts’, which indicate to the navigator the best two pairs of stations to select, are drawn up. The constant probability density contours are shown in Figs 1–6 (a) and the Loran navigational charts are given in Figs 1–6 (b). The areas covered are: Fig. 1. Japan and the adjacent seas; Fig. 2. NW. Pacific; Fig. 3. Hawaii; Fig. 4. N. Pacific; Fig. 5. NW. Atlantic; Fig. 6. N. Atlantic.

Current crises in the air traffic industry demonstrate that changes are required to present systems. The levels of delay and poor safety standards being experienced around the world dictate the need for improved Air Navigation Services (ANS). A multitude of reasons explain these problems. For instance, fragmentation of national systems prevents optimum use of the world's airspace. In addition, inherent limitations of present ANS technologies and procedures mean that it is usually not possible to separate numerous aircraft on random routings. Thus, aircraft must often plan their flights along routes and be channelled so that the necessary separation can be maintained. This results in fuel and time penalties, in addition to airspace capacity being consequently constrained. Accordingly, this paper provides an analysis of changes that should occur to ANS during this decade by evaluating current and planned technologies and procedures.

In all sciences, the experimenter is constantly seeking to improve both the accuracy of his observations and the speed with which they can be obtained. He wishes, further, to use the minimum of basic equipment, and to obtain the maximum simplicity in collecting his results. Unfortunately, these factors frequently act in opposite senses: an expensive apparatus, for example, may be required to collect accurate data quickly. In certain fields, it is even worth while deliberately to sacrifice accuracy in order to gain advantage both in speed and simplicity. Thus, in astronomical navigation, it may be possible to simplify sight reduction, to cut down on the bulk of tables carried in the air, and to reduce the time taken for observation and reduction of a sight. The penalty will be a loss in accuracy, but, provided this is not reduced beyond a certain level, it may well be worth while. A review of the requirements for air navigation, and an examination of the problems of position finding by the stars against these requirements may lead to some conclusions as to whether an advantage is to be obtained by simplifying the methods.

This article is based on a lecture to the Royal Institute of Navigation History of Air Navigation Group at Tangmere Museum on 12 May 2004. The author served as a navigator-radar – or a radar bomb aimer – within RAF Bomber Command during the mid-1960s. This article is based on his experience of this time in Bomber Command and describes how the Medium Bomber Force would have carried out their war operations had nuclear deterrence failed. In its day these plans were TOP SECRET.

The purpose of this paper is to identify and discuss official British general charts of New Zealand. The principal development period of the general chart ended when the fourth chart was published in 1885; this edition was not superseded until 1964.

Since the last Institute meeting on the Admiralty chart in 1967 the compilation office, formerly at Cricklewood, has been moved to a new building at Taunton, alongside our printing works established there in 1940. Thus, except for a small office in Whitehall, which keeps in touch with the ever changing defence scene, the whole of our organization is now concentrated at Taunton, from where every week between 30,000 and 40,000 Admiralty charts are despatched, through our agents, to navigators in every part of the world.

As readers of the Institute's Journal will know, to mark the 21st anniversary of the Institute a special edition, entitled The Navigation Explosion was published. Papers published in this edition highlight the very rapid advances which have been made during those 21 years as a result of a happy marriage between the ancient art of navigation and modern science and technology.

My first reaction on being invited by the Editor to contribute a ‘twenty-first birthday’ article on the above subject for the Journal was that there is little new to say. However, it is now 13 years since I prepared the presidential address on ‘The Place of Astronomy in Navigation’ (this Journal, 9, 1, 1956) and, apart from any other developments, space navigation has since become established as an operational science as well as a theoretical discipline. There have, in fact, been many developments and much progress in these 21 years; and, although these appear in the Journal and elsewhere mainly as gradual changes, a comparison over the whole interval reveals drastic changes, particularly in outlook and appreciation.

Of the 293 papers published in the Journal, eighty-two, or 28 per cent, have been concerned with astronomical navigation. This, however, gives a false impression of its present-day importance. There was a time when conventional astronomical navigation provided the only means of determining position, in the absence of recognizable landmarks; and it still provides the only fundamental method independent of man-controlled devices. But there has been no change in principle since accurate time became available through the combination of radio time-signals and chronometers. The papers have dealt with techniques only. The large number is evidence of the abiding interest in astronomical navigation; but it also indicates the realization that, while the principles of astronomical navigation are unchanged, the conditions of its application have undergone radical change. Techniques have had to be improved under the pressure of necessity, so that the practice of astronomical navigation is now simpler than it has ever been.

COMPASS or BeiDou is the new satellite navigation system under construction in China. In this paper, the standalone performance of COMPASS is compared to the Global Positioning System (GPS), including: Single Point Positioning (SPP), differential positioning (DGPS and Differential COMPASS) and single epoch ambiguity resolution and positioning. Based on the results, it was found that COMPASS SPP performance is clearly worse than that of GPS, due to larger broadcast orbit and satellite clock errors, especially the latter. Differential positioning performance of COMPASS and GPS are essentially similar, with GPS marginally better. COMPASS single epoch ambiguity resolution performance is obviously better than that of GPS due to more observed satellites and the single epoch positioning performance of COMPASS and GPS are similar.

Adverse effects of intoxicated driving have been well documented over the years, with clear conclusions. In addition, it is evident that the cognitive and neurological functions and reaction times deteriorate with the consumption of alcohol. Addressing the lack of literature on the subject, this paper focuses on studying the effects of alcohol on manoeuvring, navigational and decision-making ability in ship navigation. Ten participants – five cadets and five experienced navigation officers – volunteered and carried out a standard manoeuvre using a computer-controlled vessel simulator, under three different blood alcohol concentrations (0⋅00%, 0⋅05% and 0⋅08% BAC). Results from the simulations were used to assess the performance and the decision-making ability of participants under the influence of alcohol. In addition, the responses and behaviour of the simulated vessel when the navigators were intoxicated were analysed. Workload experienced by participants during the simulations were also assessed using the NASA Task Load Index. Findings of this preliminary study proved that the ability to make the correct decisions at the right time was drastically deteriorated when the blood alcohol concentration was increased.

Inland waterway transportation is one of the most important means to transport cargo in rivers and canals. To facilitate autonomous navigation for ships in inland waterways, this paper proposes a data-driven approach for predictions and control of underactuated ships with unknown dynamics, which integrates model predictive control (MPC) with an iterative learning control (ILC) scheme. In each iteration, kernel-based linear regressors are used to identify the relations between the evolution of ship states and control inputs based on the stored data from previous iterations and the collected data during operation, so as to build the system prediction model. The data are dynamically used to fix the prediction model over iterations, as well as to improve the controller performance until it converges. The proposed approach does not require prior knowledge regarding the hydrodynamic coefficients and ship parameters, but learns from the data instead. In addition, it exploits the advantages of MPC in handling constraints with minimised overall cost. Simulation results show that the controller could start from a nominal, linear data-driven ship model and then learn to reduce the path-following errors based on the data obtained over iterations.

Marine and air navigation can still learn from each other. Mariners are following aviation in adopting some routing and control but aviation could follow mariners in their refusal to accept routing and control unless it is cost effective. However it may be easier in the marine case to measure the cost and probability of a collision than it is in the aerial case. But many states have established mandatory airways and routes; originally their navigational aids were very useful and in the event of forced landing the search and rescue people knew where to look. But many airliners now have self-contained navaids like the inertial navigation system (INS) or doppler so that they can navigate off airways, and also forced landings are rare. In the history of air traffic control at first it applied only around airports; when it spread to routes many aircraft were quite happy to fly off airways. But now airways have proliferated and have become customary and respectable to airline pilots so that few complain when some states force aircraft to follow lengthy and costly routes. The only virtue of airways is their freedom, theoretically, from uncontrolled traffic and from military dangers. If A.T.C. were confined to those situations where the risk of collision without A.T.C. would be worse than, say 1 in 10,000,000, flying would be a little more expeditious, but everyone feels secure within the system and insecure, guilty and uncomfortable outside it, so A.T.C. is used universally by airliners.

This note commences with the adoption by the newly invented steam ships, of the sailing ship's custom of referring helm orders to the direction in which the tiller was to be shifted. It records something of the early resiling of the non-English speaking nations from this counter intuitive custom and draws attention to the confusion which the lack of an international approach created, especially for a ship under pilotage. The note concludes with the international uniformity achieved for helm orders by Convention in 1929.

This paper examines a new interpretation for spatial mutual information based on the mutual information between an attribute value and a spatial random variable. This new interpretation permits the measurement of variations in spatial mutual information over the domain, not only answering the question of whether a spatial dependency exists and the strength of that dependency, but also allowing the identification of where such dependencies exist. Using simulated and real vessel reporting data, the properties of this new interpretation of spatial mutual information are explored. The utility of the technique in detecting spatial boundaries between regions of data having different statistical properties is examined. The technique is shown to successfully identify vessel traffic boundaries, crossing points between traffic lanes, and transitions between regions having differing vessel movement patterns.

Until its nationalization in 1956, the physical limitations of the Canal had greatly influenced world shipowners with regard to the sizes of ships built, particularly oil tankers. Following nationalization, in an era of cheap oil and transport costs, shipowners took the initiative and began to build large tankers. Mindful of the effect that such changes would have on the tonnage of oil transported through the Canal, the Suez Canal Authority began a programme of expansion in 1958 which was to be executed in two stages. The first stage was completed by February 1964 and consisted of widening and deepening the Canal so that ships with draughts of 38 ft could be accommodated, thus allowing vessels of 60,000 d.w.t. to transit fully loaded. The second stage of development was intended to deepen the Canal to accept vessels of draughts up to 40 ft, corresponding to ships of 70,000 d.w.t. This work was scheduled to be completed by the end of 1967, but the project was not finished due to the start of the Arab–Israeli war.

When, last year, you elected me to be your President, you placed upon me the duty of delivering before the Institute the tenth Presidential Address. My predecessors in this office have been men of considerable scientific and administrative distinction, able to talk with authority in their respective fields of learning. I, however, come before you mainly as a practitioner of air navigation, the first such to be your President, concerned with the practical business of ‘how to get there’ in an imperfect, and only partly understood, world, rather than with the elegant demonstrations of a theoretical technology. The duty of preparing a Presidential Address, though onerous, has its compensations. It is the one occasion in the Institute's year when a speaker has the right to stand up before you, and to muse and speculate on controversial matters, rather than to present an account of completed work. A recent writer speculating on the future growth of air transport took as his motto: ‘Behold the turtle—she advances only by sticking her neck out’. This is true not only of turtles, but exemplifies the spirit which is needed to meet the challenge of the future: it is in such a spirit that I offer this Address.

Delays in the terminal area lead to increases in the operating cost of the aircraft involved. We assess these costs as one criterion of the effectiveness of the air traffic system in the terminal area, and to give a measure of the desirable expenditure on methods of reducing delay (e.g. improved radar, additional runways or even an extra airport). This note discusses methods of assessing the cost penalty of delays exclusively to the airline operator and gives examples for three types of aircraft, a short-range subsonic jet, a long-range subsonic jet and a supersonic transport.

Terminal area delays occur essentially because aircraft apply for use of the runway, either for take-off or landing, in a random fashion and because the acceptance rate of the runway is limited by the need to maintain safe separation between aircraft on and in the vicinity of the runway. Such delays involve penalty to the aircraft operator in terms of extra time and fuel consumed and hence of extra operating cost.