This and the following six papers were selected from the many papers presented at the 9th World Congress of the International Association of Institutes of Navigation (IAIN) held in Amsterdam, The Netherlands, 17–21 November 1997.

During the past several years, a number of important investigations, policy initiatives and national commitments relating to the future of GPS, GLONASS and their augmentations have occurred. Substantive and on-going studies of the character and configuration of a Global Navigation Satellite System (GNSS) have also been evaluated worldwide, especially by the International Civil Aviation Organization (ICAO). These efforts have been principally directed toward the definition of near- and far-term GNSS implementations that meet the needs and concerns of the international community. This paper briefly reviews some of the investigations and addresses, in particular, the concerns and requirements that may affect the future capabilities and the dual (civil/military) character of GPS. The main issues relating to the modernisation of GPS and its subsequent transition to a component of a GNSS with a viable international character are presented. These include a discussion of new signal structure options, certain changes in operating frequencies, increased signal power levels, other system alternatives and their potential impact on system performance. International issues are briefly addressed, including future performance capabilities, assurance of service, economic participation and benefit, reasonable cost, standards and international participation.

As new technologies contribute to the expanded functionality of Loran-C, and as concerns for limitations in GPS and its augmentations are raised, specific aspects of Loran-C have been developed and applied to ameliorate those limitations. Specifically, GPS availability is a concern, particularly in over-land applications. This paper discusses recent developments using very high-precision synchronisation of Loran-C transmissions, new data compression and Loran-C signal modulation techniques to augment GPS accuracy, availability and integrity over a very wide area at very low cost.

The helicopter traffic over the North Sea is performed in uncontrolled airspace over international waters. The lack of radar coverage makes the establishment of controlled airspace difficult. The development of Automatic Dependent Surveillance (ADS) and use of satellite technology for Navigation, Communication and Surveillance (NCS) have made it possible to evaluate Modified Automatic Dependent Surveillance (M-ADS) as a basis for establishing controlled airspace over remote areas without radar coverage.

Recent advances in technology have encouraged proposals for new approaches to ATC in Europe and elsewhere. Two such proposals, both rather loosely framed, are for ‘free flight’ or for ‘seamless contracts’; otherwise ‘tubes of flight’. These concepts, and variations on them, aim to increase the traffic capacity of the airspace. They have been the subject of numerous published papers. Given the declared objects of these systems, it is surprising that, nearly without exception, these papers discuss the proposals only in qualitative terms. The present paper discusses idealised versions of these systems on the basis of quantitative studies. It is concluded that the ‘seamless contract’ is very probably unworkable in Europe. ‘free flight’ is workable in principle, but there is a need for investigation of possible mechanisms by which last-minute problems may be resolved.

There is still fierce debate in the international community regarding the use and standards of electronic chart data and equipment. Whilst the standards for ecdis are now virtually complete and type-approved equipment will be entering the market during 1998, there is currently no IMO/IHO compliant enc data service from any national hydrographic office. It is expected that it will be 1 to 2 years before there is any appreciable quantity of enc data supported by a proper update service. It will be many more years before enc data becomes available to match the present coverage of paper charts, but we can expect that most major routes and the port entries of the majority of the world's trading nations will be available within a few years. This situation is examined, together with the ideas that IMO is considering to improve the availability of official electronic chart data. In addition, the distribution of electronic charts is discussed and the future trends in navigation that will occur with the availability of ecdis equipment and related data are explored.

High-precision ‘autofarming’ makes possible farming techniques previously impractical using metre-level Differential GPS-based control systems: techniques such as tape irrigation, the elimination of guess rows, and precise contour farming. A Carrier-Phase Differential gps positioning and attitude system with centimetre-level and 0·1° accuracy was installed in a large farm tractor. Four types of trajectories (lines, arcs, spirals, and curves) were identified as basic building blocks necessary to generate a ‘global’ trajectory for a realistic autofarming path. Information about each trajectory type was translated into reference state specifications that a linear controller used to control the tractor over velocities between 0·7 and 2·8 m/s to within approximately 6 cm (1 σ) without implement and 10 cm (1 σ) with implement on sloped terrain using a previously developed tractor model. These results are a significant step towards a realistic autofarming system because they not only demonstrate accurate control over various realistic operating speeds but over different types of trajectories necessary for a commercial system.

Because of increasing traffic in urban areas, public transport has to become more attractive and efficient by introducing computer-aided dynamic passenger information and on-line vehicle location. The tram location pilot system described makes vehicle scheduling and control systems independent of expensive location infrastructure (e.g. beacons). It uses on-board autonomous DGPS positioning with dead reckoning and a radio link to the control centre. The evaluation of the measured vehicle positions clearly demonstrates that operational accuracy requirements for public transport applications are met. The whole Tramway Location System (TLS) is structured into the 3 segments: on-board equipment, components of the operation centre and roadside equipment. The trial set-up for dynamic real-time measurements of the positioning accuracy is described, and the results of the evaluation of more than 7300 position fixes at 15 geodetically measured reference points along the tramway are presented. The conclusions indicate that, during runs in city environments, DGPS combined with dead reckoning achieves vehicle positioning precise enough to enable a reliable, improved and up-to-date passenger information service at the stops.

In this paper, we shall outline the reasons why the installation of shipborne equipment, which enables vessels to be positively identified from the shore and from other vessels, is so important and necessary. We shall also describe the latest innovations in this field and propose minimum standards for a transponder system.

This paper deals with the development of a location database compatible for use with the proposed Radio Data System – Traffic Messaging Channel for Great Britain. It looks at the needs for such a database and the technical difficulties that have been overcome in developing a cost-effective, automatic, production system that provides the most detailed roads location database in Great Britain.

Performance enhancement and cost reduction are driving forces in today's airline industry. In a world of cost pressures and escalating charges, research was conducted into better use of jet streams as a means of reducing costs. When operating on international airline routes, specific features of flight mechanics were adapted and tailored to fit a B747-200 aircraft, major emphasis being placed on intercepting, or avoiding where necessary, the high energy jet stream winds of the global weather system, adjusting flight profiles and modifying route structures. Operations were conducted both into wind and down wind, over a period of five years. Techniques employed show fuel may be saved regardless of the wind being a tailwind or headwind. Both fuel and time have a significant bearing on airline direct operating costs: savings of more than 1·1 percent being made on fuel and 0·786 percent on time. Limitations on using the techniques to gain maximum benefit are related to the high volume of aircraft blocking all major airways, and better quality, real time weather forecasts. The discussion looks at ways of improving the use of jet streams, as the world's airline traffic continues to grow. Forecasting upper winds, particularly in oceanic areas, needs to improve if airlines are to derive maximum benefits from these winds. There is need for further study utilising other aircraft types to ascertain what savings can result. Initial results were encouraging, using a Tristar L1011 aircraft.

Safety is a crucial issue in densely sailed waterways. Traffic guidance systems (VTS) have proven to be valuable in this respect. The effectiveness of current systems and the benefits for improvements in navigation are addressed in this paper. Relevant incidents are analysed with a risk assessment tool (Accident Sequence Precursor method) developed for complex system analyses. The method is capable of drawing conclusions on a high level: strategic and tactic events and the human errors associated with the navigator's task cycle. Changes in current VTS systems will not likely improve safety records in dense areas. Improvements might best be achieved by reducing or eliminating the human factor in incident sequences.

The increasing volume of traffic in urban areas has resulted in steady growth of the mean driving time on fixed routes. Longer driving times lead to significantly higher transportation costs, particularly for vehicle fleets, where efficiency in the distribution of their transport tasks is important in staying competitive in the market. For bus fleets, the optimal control and command of the vehicles is, as well as the economic requirements, a basic function of their general mission. The Global Positioning System (GPS) allows reliable and accurate positioning of public transport vehicles except within the physical limitations imposed by built-up city ‘urban canyons’. With a view to the next generation of satellite positioning systems for public transport fleet management, this paper highlights the limitations imposed on current GPS systems operating in the urban canyon. The capabilities of a future positioning system operating in this type of environment are discussed. It is suggested that such a system could comprise receivers capable of integrating the Global Positioning System (GPS) and the Russian equivalent, the Global Navigation Satellite System (GLONASS), and relatively cheap dead-reckoning sensors.

Civil Marine Radar (CMR) is now a mature instrument of some 50 years steady development. Following a short history, more to provide benchmarks of achievement than to satisfy historians, this paper examines what will drive the future development of CMR. The answer may not follow recent developments, but may well be the result of a fresh maritime modus operandi to fulfil the navigation, collision avoidance and safe passage needs of all types of craft operating in all types of water with different pressures and Operational Requirements (ORS). Having postulated fresh ORS, suggestions are made on how best to fulfil them in a logical and cost-effective manner.

In 1948, the port of Liverpool was probably the pioneer of European VTS, when they set up a radar station, in order to facilitate the boarding of pilots from the cutter. In 1951, Long Beach in California established a radar and VHF to facilitate port operations. Le Havre established another system and so, gradually, other ports followed. At this time commercial radar was comparatively new, and made it possible for the first time, under almost all weather conditions, to observe vessel traffic from the shore. In combination with VHF radio, a traffic surveillance system was achieved and real- time information exchange between the shore and ships became possible. Nevertheless, it was not until 1985 that the role of VTS in connection with navigation safety, traffic efficiency and environmental protection gained international recognition. This recognition is contained in an IMO resolution, which constitutes the VTS guidelines.

Among the many primary causes which lead to a shipping casualty, those of wrecking, stranding or coming into contact with fixed coastal structures depend (although not exclusively and only under specific conditions of visibility) upon the efficiency of the lighthouse and navigating lights network of a national coastline. The analysis of the shipping casualties involving Greek ships in the Greek seas revealed that, despite the recent introduction of sophisticated navigating aids for the prevention of stranding and contact, the share of the corresponding casualties remains unchanged. It appears that for coastal shipping operations, and in particular for port approaches, the traditional light navigating aids are and will always provide an irreplaceable safety service for navigators. This is mainly attributed to their technological simplicity which offers a high level of signal reliability and friendliness for the navigator.

Much has been written on the subject of aircraft collision risk and avoidance over the past 50 years. As a particularly interested aviator (a military and civilian pilot for the last 32 years), with a limited memory for the mathematics I studied at school, I have read several of these treatises with interest. I do, however, feel that the advent of modern, accurate navigation systems has changed the distribution of collision causes radically. We should be concentrating, not on the risks of aircraft accidentally flying into each others' paths, but on the risks of them deliberately doing so.

That statement requires explanation, of course. There is a risk of one pilot deliberately and willingly putting his aircraft in the path of another (a terrorist or suicide for example), but the risk is considerably less than that of a pilot who does it unwillingly, but equally deliberately.

Pike has pointed out the increasing risk of collision resulting from the expansion of the fast commercial vessel fleet and has made some proposals for alleviating the problems. This paper points out some difficulties with Pike's proposals and suggests, instead, a simpler modification of the philosophical basis of the colregs which would equally alleviate the greater risks of collision introduced by higher speed craft.

I understand that The Netherlands are pressing the IMO to change the COLREGS so that high speed craft (HSC) have the obligation of keeping out of the way of other vessels.

There is an IMO definition of high speed craft which was adopted by resolution MSC 36(63) in May 1995. It is the International Code of Safety for High Speed Craft. It covers vessels on international routes but does not cover, for instance, warships, troopships, fishing and pleasure craft. However, for the purpose of the COLREGS, I am sure that this definition should be widened and then incorporated.

I agree with many of the points in Mr R. D. Pike's article printed in this Journal in May 1997.