In this technological age, when an artist of nautical astronomy is fast becoming a figure of history, there is a tendency to regard astro-navigation as something that went out with the dodo. It would be as well to remember, therefore, that despite the widespread use of radio navaids from the early years of World War II, astronomical navigation remained the only world-wide fixing system until the launch of the Transit navigation satellites during the 1960s. The truth is that the first half of the present century saw enormous advances in both its methods and practice and the fact that it is still in wide use can be judged by the large number of Nautical Almanacs sold annually.

Since the early nineteen-seventies, when the price of fuel went up so dramatically, airlines have been seeking methods of saving fuel. Climb, cruise and descent speeds were refined to give the most economical operation. Advisory systems came on the market, but these did little more than give crews information which could be obtained from operations manuals. Then equipment such as performance management systems (PMS) and flight management systems (FMS) was produced. The potential of these systems can be measured by the number of airlines who have purchased the equipment, and also by the fact that most of the new generation of aircraft are being built with PMS as part of the standard aeroplane.

The second half of the present century has witnessed the advent of intensified conflict of sea-use. The elements of this are well known: expanding international trade, carried in more numerous, often larger, and faster ships; the exploitation of oil and gas deposits under the sea bed; and always the fisheries, life-support of much of the still increasing population of the world.

The particular aspect of sea-use conflict which the establishment of Vessel Traffic Services (VTS) is intended to resolve is that arising from the concentration of shipping in the approaches to great ports, and in straits. The protagonists in this conflict are, on the one hand, any authority on shore which, with or without the sanction of international agreement, seeks to impose order upon the flow of vessel traffic, and on the other, the masters of vessels, each of whom is responsible ‘under God’ for the safe navigation of his ship. The pilot, as professional adviser to both the protagonists is now acquiring a new responsibility as ‘ honest broker’ between the ship master and the port authority. Indeed, it would accord with this role if the pilot were to be paid, in some proportion, by the port authority as well as by the shipowner. Be that as it may, since the establishment in 1948, at Liverpool, of the world's first port radar station, it could be said that experience has confirmed that by far the most important features of a Vessel Traffic Service are its radar coverage, which provides ‘the authority’ with an overview of all traffic in the area of responsibility; and the v.h.f. radio network for voice communication with the pilots, shipmasters, tugmasters and other individuals directly concerned with the operation of the port. It is a curious fact that, so far, there has been no concerted move to introduce the technological device required to enable the port operator to correlate an echo on his radar display with its corresponding identity and hence, radio call sign. It is the aim of this paper to compare the existing means of identification and recognition of radar contacts in a VTS with what is technically and economically feasible; to determine the operational requirement; and to set out the characteristics of a system which would meet the requirement.

New techniques of measurement make it possible in 1984 to determine positions on the surface of the Earth to a much higher precision than was possible in 1884. If we look beyond the requirements of navigation we can see useful applications of global geodetic positioning to centimetric accuracy for such purposes as the control of mapping and the study of crustal movements. These new techniques depend upon observations of external objects, such as satellites or quasars rather than stars, and they require that the positions of these objects and the orientation of the surface of the Earth are both known with respect to an appropriate external reference system that is ‘fixed’ in space. We need networks of observing stations and analysis centres that monitor the motions of the external objects and the rotation of the Earth. Observations of stars by a transit circle are no longer adequate for this purpose.

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.

The three papers which follow were presented at a meeting sponsored jointly by the Institute with the Royal Aeronautical Society, held in London on 20 February 1985 with the President, Mr J. E. D. Williams, in the Chair. Mr Attwooll is with the Chief Scientist's Division of the Civil Aviation Authority, Captain Lister is a member of the Flight Operations Inspectorate of the same Authority and Captain Grieve is the Chief Pilot of Britannia Airways.

In text books on astro navigation, the fact that the Earth is not spherical in shape is seldom discussed and therefore one presumes it does not have a significant effect on the accuracy of sight reduction, and yet it is quite remarkable that it is not uncommon to find discussions of the phenomenon of augmentation (a correction to the altitude or semi-diameter of the Moon that amounts to about 0·25 at an altitude of 60°) in these books. It will be shown that discrepancies of the same order of magnitude as augmentation may be present in the calculated altitude of the Moon because of neglecting to take into account the shape of the Earth.

In the following (1) rigourous expressions for correcting the observed altitude and geocentric declination of a body close to the Earth are derived, (2) simple expressions which are sufficiently exact for the purpose of sight reduction for the Moon are given, and (3) an example, using different methods of reduction, is shown in detail to illustrate the theory.

Several years ago, when Airbus Industrie launched their twin-engined A 300 Airbus, it became apparent that a new generation of long-range aircraft was about to add a different facet to the shape of international air travel. The enormous power available from the big fan engines coming into use meant that adequate performance was available even when an engine failure meant the loss of half the installed thrust. Coupled to this was a standard of fuel economy and tank capacity which meant that the new aircraft were capable of operating over ranges far in excess of those previously attained by twin-engined aircraft.

The design of a route through Dover Strait to Europoort for very large carriers (VLCs) with a draught of up to 22 metres is described. The results are compared with established international safety criteria. A number of subjects for further study by institutes of navigation are mentioned. Van Riet (DG Shipping and Maritime Affairs), Kaspers (Public Works, North Sea Directorate) and Buis (Hydrographic Service, Royal Navy) participated in this design process. The views expressed, however, are those of the authors and not necessarily those of their organizations.

Since 1974 deep-draught ships of up to 20·70 metres (68 feet) have been navigating the English Channel and the Dover Strait with destination Europoort in the Netherlands. To a lesser extent ships with these large draughts have been passing through the Strait with destinations in Scandinavian countries.

The possibility of reducing the current vertical separation minima in order to increase traffic capacity on economical flight levels has been discussed mainly at the RGCSP (Review of the General Concept of Separation Panel) meetings of ICAO. A collision risk model based on the mathematical model developed by Reich (1966) has been adopted for evaluation of safety of air traffic systems under consideration. This collision risk approach requires several parameters which should be estimated from empirical data on navigational errors, traffic dynamics, etc.

When considering user charges for the provision and maintenance of marine aids to navigation, it must be recognized that the basis on which they are calculated and levied is to a large extent due to historical accident. There is no internationally recognised system for levying these dues and every country has its own ideas as to how much money, if any, should be raised by this means.

User charges paid by shipping for marine aids to navigation normally fall into two categories. First there are national charges which go towards the running of the national lighthouse authority, either in whole, or in part. Such charges are referred to in this paper as ‘light dues’.

The ocean environment within which navigators operate is not only physical in character; it is an economic, political and legal environment as well. One of the most significant factors influencing general environmental development in recent years has been the rapid advance and expansion in the field of ocean and ocean-related technology. Much of this technological evolution, while helping to reduce the restrictions imposed by the physical characteristics of the oceans, has created new challenges of an economic, political and legal nature.

Britannia celebrated its 21 st anniversary in 1983. From the beginning in 1962 with three Constellations, Britannia's 1985 fleet is four Boeing 767s and 25 Boeing 737 aircraft. Britannia is now the largest independent airline in Europe in terms of passengers carried and passenger miles flown. Our present route structure, within a radius of 2500 nautical miles of London, is between some 20 UK airfields and over 70 overseas destinations. The range of the B 737 fleet extends to 1900 n.m. with full reserves and a full payload of 130 passengers. The range of our present B 767 fleet, under similar conditions, extends to 2800 n.m. with a full payload of 273 passengers. This payload—range capability is so limited by our decision to operate these aircraft for the time being with a reduced maximum gross weight. Both fleets are operated by 2-man flight deck crews.

The paper by Spencer and Blades, both of the Department of Psychology in the University of Sheffield, was presented on 14 March 1984 at an Institute meeting held in London to discuss Psychology and Navigation.

From its earliest moments, the young organism has a need to track and integrate into some scheme of knowledge the location of salient objects and places; and thence to develop navigational strategies for efficient movement through space. In the case of human young, their initially limited mobility constrains the extent of their active explorations, and thus their range of experience; and adult protectiveness (somewhat heightened in the modern, suburban nuclear family setting) continues to limit such explorations even when the child is fully capable of extensive movement round the local area (Pick and Acredolo, 1983).

Commercial interests now demand a close awareness of fuel consumption, which is one of the major costs in vessel operation. This paper outlines one shipping operator's attempts to monitor and improve economic performance as indicated by fuel consumption alone. The authors are well aware that some aspects of operation, such as main engine performance variables, are closely and easily monitored whilst others such as environmental effects are not. They have therefore adopted a ‘macro-economic’ approach to the analysis and advice on Fleet operation in this instance, attempting to monitor the vessel operation system as a whole. Thus fuel consumption is used as a yardstick and it is this particular variable which is the subject of management focus. Although many of the inputs to the complete economic equation are necessarily unquantifiable in precise terms, it is considered that a valid determination of performance is attainable from a scientifically based overview.

When the satellite era commenced more than a quarter of a century ago, one could hardly foresee the world wide revolution it heralded in the development of aids to navigation for merchant shipping. However, early investigations into the possible application of satellites to maritime needs led to an understanding of the powerful potential of satellite techniques for navigation. It became clear that if the international maritime community was really interested in a global all-weather, high-precision and commercially viable navigation system; such a system could only be satellite-based. This is evident from the situation that has recently arisen in IMO, where after exhaustive discussion on the mandatory carriage of electronic position-fixing equipment on ships in designated areas, the organization could not express a preference for any particular aid, until it was decided that efforts should be made to develop a global satellite navigation system capable of meeting a new standard of navigational accuracy. Moreover, in preparing the navigational accuracy standard, account was taken of experience gained with existing satellite navigation systems.

The subject of this paper is the merchant marine user requirements for position fixing systems (a merchant marine with approximately 40000 ships operating). These requirements are varied and can be summarized as follows:

(i) accuracy

(ii) availability (possible fix frequency)

(iii) reliability

(iv) coverage

(v) user skill and workload

(vi) presentation of information

(vii) ambiguity

(viii) environmental constraints

(ix) operational constraints

(x) system control

(xi) system user costs.

These eleven requirement elements should together serve the two basic purposes of merchant marine navigation: (a) provide a service adequate for safety and (b) enhance economic performance/benefit.

For more than a century and a quarter ships' crews of the world's voluntary observing fleet have made meteorological and surface current observations. Those observations recorded in the ships' logbooks are the backbone of the Marine Archive now held in the Meteorological Office, Bracknell, UK. Much use is made of computer processing for providing suitable statistical data which form the basis of maps and current roses. This article outlines the method of processing used in the Netherlands, illustrating various situations the observer at sea may encounter. The supposition that the use of modern navigation equipment could hamper the making of current observations is discussed, and situations that could cause the reduction of accuracy and reliability of current mean values are mentioned. In essence: how reliable are surface current observations from ships collected in the past few years, and particularly those that will be collected in the years to come?

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.