This, and the following paper, were first presented during the European GNSS98 Symposium held at the Centre de Congrès Pierre Baudis, Toulouse, France, from 20 to 23 October 1998; however, both authors have provided updated scripts for use in this Volume of the Journal.

This paper provides an update of the development and implementation of the United States of America Federal Aviation Administration (FAA) Wide Area Augmentation System (WAAS) and Local Area Augmentation Systems (LAAS). It also addresses FAA efforts to implement these satellite navigation technologies into the US National Airspace System (NAS), as well as interoperability efforts concerning Satellite Based Augmentation Systems (SBAS) between the FAA and other worldwide Civil Aviation Authorities.

In his Presidential Address at the 52nd Annual General Meeting of the Institute, held in London on 21 October 1998, Air Commodore Pinky Grocott gave an analysis of the causal factors that resulted in the loss of 913 large sailing ships during the period of the Revolutionary and Napoleonic eras (1793–1815). Navigation and weather factors predominated, often aggravated by poor and untimely decision-making. Many of the lessons learnt are equally relevant today.

This paper was presented at the World Congress of the International Association of Institutes of Navigation (IAIN) held in Amsterdam, The Netherlands, 17–21 November 1997.

Remote, or shore-based, pilotage means different things to different people, despite a definition being produced by the European and International Maritime Pilots Associations. The debate about it is set in the context of increasing public awareness of the environment and a downward pressure on costs; these in themselves make for uncomfortable bedfellows. However, this sets the scene for the current aspirations within the European Union for vessel traffic management and the ongoing research into Vessel Traffic Services (VTS) and Vessel Traffic Management and Information Services (VTMIS). The technology to implement navigational assistance of a fairly high order is already in place, but there are still problems to be overcome before the concept can be taken further. Commonly recurring concerns over remote pilotage are the inadequacies of radar, difficulties with language, lack of ‘feel’ for the ship, which includes the on-board pilot's assessment of the quality of the vessel's crew, and the lack of ship motion data. Differential GPS is now capable of aiding automatic docking of some specialized vessels, but it has emerged, most recently at the IALA VTS Committee meeting, that ECDIS has shortcomings when being considered as the geographic information system of a VTS. Transponders are the subject of yet another debate, but will the data that they can convey be able to replace an on-board pilot?

This paper, and the following six papers, were presented during the NAV 98 Conference held at Church House, Westminster, London on 9th and 10th December 1998. A full listing of the Conference, and how to obtain a copy of the proceedings, is shown on Page 300.

The existing Loran-C and Chayka infrastructure can, with some minor changes, become a very powerful augmentation system for GNSS (GPS, GLONASS and the future Galileo). Delft University initially proposed the Eurofix concept in 1989. Although the necessary modification to the LF navigation systems are minimal, the GNSS user may get significant benefits from the Eurofix signals in terms of accuracy, integrity and availability. The reason is the high signal structure, signal propagation, and the operations dissimilarity of both systems. The broadcast correction and integrity data improves GNSS accuracy down to the metre level. In this way, the measured Loran-C and Chayka ranges are continuously updated. Thus, in the case of GNSS signal interruptions, highly calibrated Loran-C/Chayka may take over the navigation function. Tests carried out in Europe at the Loran-C station at Sylt (Germany) drew large international attention, leading to further tests in the USA by the US Coast Guard in 1998. Recently, a Dutch–Russian consortium implemented Eurofix on the Chayka transmitter at Bryansk (Russia) which is now successfully broadcasting DGPS as well as DGLONASS correction data. This paper highlights some on-air Eurofix DGPS performance experiments carried out in Europe and the USA. With all the European Loran-C and Chayka transmitters modified, Eurofix can be used all over the European continent. As multiple stations can normally be received simultaneously, the user may locally apply networked DGNSS, which may reduce spatial decorrelation effects significantly. Post- processed results of this Regional Area Augmentation System are presented.

This paper presents the application of GNSS1, or more precisely of Satellite Based Augmentation Systems (SBAS), to vertical separation for en-route, approach and landing operations. Potential improvements in terms of operational benefit and of safety are described for two main applications. First, vertical separation between en-route aircraft, which requires a system available across wide areas. SBAS (EGNOS, WAAS, and MSAS) are very well suited for this purpose before GNSS2 becomes available. And secondly, vertical separation from the ground during approach and landing, for which preliminary design principles of instrument approach procedures and safety issues are presented. Approach and landing phases are the subject of discussions within ICAO GNSS-P. En-route phases have been listed as GNSS-P future work and by RTCA for development of new equipments.

This paper considers the issue of operating aircraft through the North Atlantic's Minimum Navigation Performance Specification (MNPS) airspace. Noting that aircraft constantly strive for reduced fuel burn and uplift, it describes how flight operators and pilots conduct safe, efficient flights through the region. Reference is made to mechanisms of the North Atlantic MNPS airspace in terms of its Organized Track Structure and other routes that exist. These different structures emphasize the level of flexibility available. Flight planning procedures and requirements necessary to obtain oceanic Air Traffic Control (ATC) clearances are mentioned, as is an account of how communication and position reporting procedures operate to apply the Mach Number technique. Other aspects of MNPS operations such as ETOPS operational restrictions, meteorological effects, the employment of Reduced Vertical Separation Minima and planned regional changes aim to provide an overview of the MNPS system's current and future air traffic management.

Digital Selective Calling (DSC) is causing serious problems for Search and Rescue (SAR) providers. Administrations must seriously consider the humanitarian and legal implications of continuing the implementation of DSC. They may be in violation of the Safety of Life at Sea Convention, the International Convention on Maritime Search and Rescue, 1979, and the United Nations Convention on the Law of the Sea, 1982, by knowingly implementing communications technology that may jeopardize lives at sea even though the primary intent of DSC is to establish a suitable distress alerting method. States may very well open themselves to legal liability if loss of life or environmental damage can be linked in any way to the known faults of DSC.

The rapid development of differential GNSS transmissions via low-frequency maritime radiobeacons has further increased the occupancy of an already over-crowded frequency band. This has resulted in interference between stations, with consequent reductions of coverage. The paper suggests a re-allocation of channels within this band in Europe to be carried out, taking careful account of the known groundwave and skywave propagation of both wanted and interfering signals and the distribution of atmospheric noise. A novel algorithm is proposed for re-allocating frequencies. The resulting band plan is shown to offer substantially increased coverage for DGNSS radiobeacons while preserving the performance of marine and aeronautical direction-finding beacons, the latter remaining on their original channels.

Operating a fleet of ships in all weathers and environments poses certain risks, and navigational incidents such as collisions, groundings and vessel strikings are bound to occur. The Royal Navy has always conducted extensive inquiries into the serious navigational incidents in order to establish the cause and so prevent reoccurrence. However, many less serious navigational incidents occur which, if collated and analysed on a database, could help better understanding of the nature of such incidents. This paper describes how a database that met these needs was designed and developed. Once completed, the database was analysed to compare trends between different vessel types and incident categories.

With the assistance provided by the white cane or guide dog, most blind pedestrians can find their way to known destinations along familiar routes. Finding new or known destinations along unfamiliar routes is more challenging. Before such a journey is attempted, detailed instructions must be acquired. The difficulty of obtaining and then reliably following such instructions deters many blind pedestrians from travelling alone in unknown areas. This paper demonstrates a technological approach, by way of field trials, that supplements the existing aids and eliminates the need for sighted guides. The approach has the potential to offer greater independence to the blind person. The investigation suggests that the methodology used in personal navigation systems for the sighted is sub-optimal for guiding the blind pedestrian. Suitable extensions are introduced, and the results show the proposed methodology is efficient for guiding the blind individual to unknown destinations in the chosen field trial environment.

The following paper reports on the progress of a large collaborative project in the UK to investigate novel strategies for the implementation of GNSS within all phases of marine navigation. The project is funded by the UK Government (Engineering and Physical Sciences Research Council) under the leadership of the IESSG at the University of Nottingham. The project receives the support from a prestigious team of collaborators which include the UK Ministry of Defence Hydrographic Office, Trinity House Lighthouse Service, Northern Lighthouse Board, Commissioners for Irish Lights and the Port of London Authority. This consortium is of strategic importance, as their operations encompass the provision of aids to navigation for all phases of marine transport within the UK and elsewhere.

Recent developments in remote imaging equipment carried on satellites have given the scientific community a vast amount of new information about the Sun and its atmosphere. Media coverage of the remarkable discoveries accompanied by impressive images of the Sun's atmosphere, and linkage to the loss of a television satellite over the United States, have focused public attention on the existence and effects of the Solar Wind. This paper sets out to illustrate the impact of the Solar Wind on radio aids to navigation, and to look at the possible effects on present and proposed systems.

This paper presents the results of a study carried out in the Greater London area to assess and characterise the performance of the Global Positioning System (GPS) for vehicle positioning in urban areas. The performance assessment addresses, in varying levels of detail, the issues of service coverage, positioning accuracy, integrity and availability of service. The project was supported by Racal Survey Limited and is part of the wider research at Imperial College in the area of architectural design and testing of Advanced Transport Telematics (ATT) systems. The results highlight the shortcomings of GPS as the sole means for in-car navigation in urban areas and details the temporal and spatial considerations to be taken into account in the process of designing an integrated positioning system capable of meeting navigation requirements placed on ATT systems.

This paper is based on the results of the ‘GNSS Support Task’ study for the European Commission, DGXIII. It summarises the results of the cost benefit analysis in terms of coverage, accuracy and safety requirements for different types of user and describes the most cost-effective GNSS 2 architecture. These analyses also assume that the overall system is layered into wide area, regional and local systems. The future planning of satellite navigation is essentially driven by the wide area requirements and ensuring that these are global and seamless. There is some flexibility in coverage and accuracy for a wide area system in that it can be augmented regionally or locally if required, but it must provide the highest level of safety required. The paper approaches the architecture for a future navigation system from this safety aspect. An analysis of the chosen architecture shows that the required safety performance can be met. An implementation plan is described which allows a gradual evolution from the first system to be realized for safety critical operations to a fully civilian owned and operated system.

Self-organising radio systems have been proposed for aeronautical and maritime communication, navigation and surveillance applications. In aviation, the introduction of the VHF Data Link (VDL) Mode 4 is currently being discussed, while the implementation of Automatic Identification Systems (AIS) is planned in the maritime domain. Operating in an autonomous mode, a self-organising radio system employing Time Division Multiple Access (TDMA) does not require a terrestrial infrastructure, such as base stations. The concept of self-organisation is based on the cooperative behaviour of a large number of users sharing a common VHF radio channel. Analyses have shown that uncoordinated stations, so-called hidden users, can cause interference in self-organising radio systems. This paper presents two different approaches to autonomous self-organisation together with the results of investigations of intra-system interference. Such analyses may help to introduce potential improvements to the system performance, which reduce the effect of hidden users in this very promising GNSS-based technology.

A variety of operational systems are vulnerable to disruption by solar disturbances brought to the Earth by the solar wind. Of particular importance to navigation systems are energetic charged particles which can generate temporary malfunctions and permanent damage in satellites. Modern spacecraft technology may prove to be particularly at risk during the next maximum of the solar cycle. In addition, the associated ionospheric disturbances cause phase shifts of transionospheric and ionosphere-reflected signals, giving positioning errors and loss of signal for GPS and Loran-C positioning systems and for over-the-horizon radars. We now have sufficient understanding of the solar wind, and how it interacts with the Earth's magnetic field, to predict statistically the likely effects on operational systems over the next solar cycle. We also have a number of advanced ways of detecting and tracking these disturbances through space but we cannot, as yet, provide accurate forecasts of individual disturbances that could be used to protect satellites and to correct errors. In addition, we have recently discovered long-term changes in the Sun, which mean that the number and severity of the disturbances to operational systems are increasing.

The Instrument Landing System (ILS), in its present 90/150 Hz format, had its beginnings in the United States and England during the years 1939 to 1945. Since then, it has served the aviation community worldwide. There have been many improvements to cope with ever increasing traffic, crowded airports, and difficult siting problems. There are those who say that it's time to replace the system with newer technology; are they right?

This paper, and the paper which follows it, were first presented at the IBC '98 Conference ‘Space-Based Navigation Industry’, which was held in London, 11–12 June 1998.

In conventional arable agriculture, position within the field was usually irrelevant! However, the advent of precision agriculture, wherein inputs are targeted according to locally-determined requirements within the field, has opened up a potentially large market for GPS. Indeed, it was the availability of GPS which permitted the development and implementation of precision agriculture – a concept which holds the promise of significant economic and environmental benefits to the farmer. This paper indicates the technical requirements for GPS and presents three case studies where a positioning system is required.

Digital electronics have caused massive changes to navigation technology in the latter half of the twentieth century. This paper presents an alternative view to much of the commentary on the future of electronic navigation. It is written from a small craft perspective, although the principles are of value to commercial and naval shipping. Essentially, it proposes the development of environmental simulation as the basis for computer-hosted charting systems on vessels. This is drawn from the author's experience of developing the DyGeo system for environmental simulation, of which the navigation version forms a part. It stresses that much of the additional data we have placed on charts this century has been cultural in content, and necessitates a large bureaucratic system for its maintenance. An environmental system requires different types of inputs, but can be largely self-maintaining. The advent of the inexpensive, portable, personal computer has put this sort of facility in the hands of the leisure mariner as well as professional navigators.

This paper discusses the technical, administrative and certification compatibility issues associated with satellite augmentation of GPS/GLONASS. It indicates that the Signal-in-Space specifications are central to compatibility and interoperability. ICAO Standards and Recommended Practices are a key mechanism for interoperability. The paper recommends that one standard be implemented worldwide. It also urges a mechanism for the co-ordination and management of augmentation services.