This paper is intended to provide an operator's view of the impact of GPS on the air transport industry. The discussion centres on use of GPS for the en-route, oceanic, terminal area and precision approach phases of flight. In summary the author suggests the following:

(i) Inefficient use of airspace is costing the airlines a huge amount of money. However, GPS is not a pre-requisite of a move towards more efficient use of that airspace, although it will be required as part of the eventual CNS/ATM package. In the near term, better usage of current equipment such as IRS and DME, together with the introduction of ADS can provide the required level of accuracy for reduced separation in en-route and oceanic airspace.

(ii) There is a real need to provide navigation for non-precision approach worldwide, independent of ground-based infrastructure. This is the area in which GPS can provide the most immediate improvement to safety.

(iii) There are still a large number of questions hanging over GPS for precision approach. This leads the author to believe that it will not be capable of replacing ILS for the more critical Cat 2 and 3 applications quickly enough to avoid the loss of these capabilities in some critical locations. For this reason, it is postulated that MLS will be required in Europe, at least. Even if MLS is not required, there will still need to be a means of dealing with the transition away from ILS and for this reason the concept of a multi-mode receiver has been developed.

In January 1993 our target for a circumnavigation was eighty days but, having been struck halfway between Africa and Australia by an object which holed our starboard hull, we were forced to pull out, and a Frenchman – Commodore Explorer – got round first in just 18 hours under the magic Jules Verne figure. It all seemed to be over, except that we were convinced it could be done more quickly – in seventy-seven days anyway, and perhaps (holding our breath) even seventy-five with some luck. We were keen to have another go at winning the Trophy and fortunately so was our sponsor – the New Zealand Apple and Pear Marketing Board. Preparations began immediately.

In May 1993, in support of Eurocontrol's WGS 84 Implementation Programme, a project was undertaken to assess the accuracy of navigation aid coordinates. The exercise involved flying a route over a number of European countries, in an aircraft which was equipped for multi-DME ‘data puddle’ position updating, and which also carried Global Positioning System (GPS) receivers. This test flight, carried out under contract to Eurocontrol, involved two parties, namely the Defence Research Agency (DRA) Bedford, who provided the airborne trials facility and DME data, and the Institute of Engineering Surveying and Space Geodesy (IESSG) at the University of Nottingham, who provided an analysis of the DME coordinate accuracy.

The aim of this test flight was to assess whether it is possible to determine independently the (WGS 84) coordinates of DME ground stations from the air, by using the same DME range measurements which are used to update aircraft position information in-flight. The procedure used to determine DME coordinates involves reversing the position updating principle. Instead of taking the DME ground station coordinates as known points and using the DME range measurements to determine the aircraft's position, the aircraft's position is independently determined (from DGPS) and the range measurements are used to estimate the coordinates of the DME ground stations.

Reduced manning levels, the lack of skilled maritime labour and new satellite navigation systems have created a need for electronic charts in merchant ships. Developments in information technology have made it possible to design and produce these charts and the equipment to display them. It is essential that shipowners and others understand the issues which affect the use of these charts and equipment. It is also important for users to understand the effects that the revolution in satellite technology is having on all types of charts, paper and electronic. Only with this knowledge can shipowners appreciate the economic and operational benefits of using electronic charts, and IMO complete its work on the safety rules for the carriage and operation of all types of electronic charts and equipment for merchant ships.

The International Maritime Consultative Organization (now IMO) carriage requirement for ARPA began to take effect in 1984 and became progressively mandatory worldwide; prior to this, for certain classes of vessels trading to the USA, a national requirement was introduced in 1982. These radar plotting aids perhaps constituted the first widespread use of computing power aboard merchant vessels. In implementation, even the early ARPAS were much more than the mere plotting aid which their name suggests. Sophisticated processing gave the navigator a system which offered significant assistance in scenario analysis, with the well known ability to display graphically the effect of a trial manoeuvre being the most active element of the system.

This paper, and the following seven papers, were presented at the Institute's NAV94 Conference held at Church House, London, in November 1994. The full proceedings may be obtained from the Director, RIN, price £25.00 (plus p & p).

I should start by explaining that the main purpose of my paper is to pass on the Inmarsat vision of satellite navigation in the future.

But first a little about mobile satcoms, our original reason for being. If you have followed us even at a distance you will be aware of:

• (i) how we started with satcoms for ships;

• (ii) how we contributed to a new maritime safety system;

• (iii) how we developed an aeronautical satcoms system in close cooperation with the civil aviation world;

• (iv) how land-mobile communications now account for one-third of our total traffic.

During the summer months of 1994 the yacht Jester undertook a seagoing investigation into some of the navigational problems that would have confronted the Portuguese discoverers of the thirteenth and fourteenth centuries returning to mainland Portugal from the coasts of Africa and the Atlantic archipelagos. The investigation was made at the suggestion of the maritime historian D. W. Waters to illuminate one aspect of how astronomical navigation was first introduced at sea in the west.

We have to welcome this initiative to bring together, during these three days of NAV94, system designers, service providers, users and administrations. We are all concerned with the need to contribute to the efficient functioning of the transport system taken as a whole, and the Ministers of Transport have underlined the contributions that can be made by satellite navigation systems and information technology.

Radar and ARPA are used both for anti-collision purposes and for navigational purposes. The requirements for ‘ground-stabilization for navigation’ and ‘sea-stabilization for collision-avoidance’ seem to exclude each other. Since the development of True Motion radar (TM), there is the need for an input of Own Ship's velocity. Since then, the mode of velocity input and, consequently, the mode of stabilization have been the subject of controversy. The problem became even more important by the introduction of ARPA, by the use of video map overlays and by the introduction of complex integrated navigation systems including radar.

The risks involved in maritime transport are very much greater now than was formerly the case. This has been accompanied by a considerable increase in the damage resulting from certain accidents. Maritime traffic management has been made necessary not only for reasons of safety but also productivity and comprises two main types of measure: first, laying down and enforcing suitable regulations and secondly, providing navigators with real time information which is not available to them on board from the Vessel Traffic Services (VTS).

Section 2 of this paper is a general description of the techniques used in maritime traffic management and an account of possibilities for the future. Section 3 describes a feasibility study for a traffic monitoring aid system based on VTS and using a knowledge based system.

This paper is based on one which was first published in the journal, Recherche Transports Sécurité, issue no. 9, 1993.

The availability of an aeronautical mobile satellite service and the emergence of a global navigation satellite system should enable CNS services to be established for civil aviation, virtually worldwide. This paper discusses how the development of a low-cost ADS system, employing these satellite services, might be used to the advantage of European air traffic management (ATM). It indicates that the earlier action is taken, the greater will be the potential benefits. This paper is an updated version of that presented at the NAV94 Conference in November 1994.

Today, no single technology has more broad-reaching potential for worldwide civil aviation than the future applications of satellite technology. These applications represent the greatest opportunity to enhance aviation system capacity, efficiency and safety since the introduction of radio-based navigation systems more than 50 years ago. The foundation for this optimism is the Global Positioning System (GPS), a satellite-based radio navigation system operated and controlled by the United States Department of Defense (DoD). In December 1993, DoD declared GPS to be in initial operational capability (10c), which means 24 satellites are now in orbit, available and usable for satellite navigation. The Federal Aviation Agency (FAA) responded to this potential through initiation of a comprehensive satellite programme involving government, industry and users to expedite research, development and field implementation of satellite-based navigation services.

A device has been developed to enhance the radar conspicuity of navigation buoys. It is also very effective on small craft. This paper describes the specification and testing of the device and discusses the regulatory position regarding its use.

Captain George Vancouver's survey of the North Pacific coast of America has been characterized as being among the most distinguished work of its kind ever done. For three summers, he and his men worked from dawn to dusk, exploring the many inlets of the coastal mountains, any one of which, according to the theoretical geographers of the time, might have provided a long-sought-for passage to the Atlantic Ocean. Vancouver returned to England in poor health but, with the help of his brother John, he managed to complete his charts and most of the book describing his voyage before he died in 1798. He was not popular with the British Establishment and, after his death, all of his notes and personal papers were lost, as were the logs and journals of several of his officers.

State-of-the-art avionics achieves very good reliability, and the electronics in the current generation of communication and navigation satellites is sufficiently good to allow a design-life of around 10 years. Nevertheless, failures will arise. The purpose of failure analysis is to identify the consequences if a particular module does encounter a failure, and to ensure that, by system redundancy or through operational procedures, the effect and/or its probability of occurrence will be acceptably safe. This paper is a contribution to the discussion on the strength and weakness of redundancy in satellite-based Communication, Navigation and Surveillance (CNS) systems as envisaged by the International Civil Aviation Organization (ICAO) to be an integral part of the future air navigation system. This particular paper makes a comparison with today's terrestrial-based systems.

Vessel traffic service systems (VTS systems) have been established, throughout the world, in areas of high traffic density. These systems, operating with such tools as VHF radiotelephony, land-based radar installations and ship's data processing, gather information to respond to collision and grounding danger, to organize traffic flow and assist allied activities. It is expected that VTS systems should effectively reduce the number of collisions in the VTS area. But efforts for collision avoidance can only be successful if the VTS operator in front of the shoreside radar screen is precisely instructed as to which measurements he has to make to identify a risk-of-collision situation. Uncertainties about the direction in which ships must take evasive action arise in VTS areas, where ships are free to engage in encounters.

Since a paper on Datatrak was presented at Warwick to the NAV90 conference, the system has improved markedly. Each of its three major components has been further developed, giving increased functionality and reliability while allowing the service to be provided at a reduced cost.

Map reading has always been and will continue to be a vital military skill. The ability to relate map to ground and vice versa is an essential skill for all ranks. Having determined his position and that of his objective, a soldier must be able to navigate between the two in the most expeditious manner. The advent of the Global Positioning System GPS has not diminished this requirement. Map reading and navigational skills are practical subjects that must be regularly practised and assessed if skills are to remain high.

It is of historical interest that it was written instructions in the form of periplus, rather than the paper chart, that are recorded as providing the first form of document to guide marine navigators. Therefore perhaps the wheel has turned full circle when it is the digital information rather than the video display that may provide the basic guidance for the navigation of ships in the future. In 1986, when IMO and IHO set out to develop standards and specifications, it was decided that the product to be specified would have to be equivalent to the paper chart. In so doing they were following the guidance of the SOLAS Convention, which requires charts to be carried in Chapter V Regulation 20 and, in Chapter 1 Regulation 5, permits Administrations to substitute equivalents. Regulation V/20 does not state that the charts to be carried be paper but, until recently, it has been assumed that this is what is meant. What is explicit, is that the charts to be carried are to be ‘adequate, up-to-date and necessary for the intended voyage’. Following this guidance, the IMO/IHO Harmonizing Group attempted to specify an electronic system that would be equivalent to a printed paper document. This proved to be no easy task. It was extremely difficult to claim that an electronic system can be as durable and as generally reliable as a sheet of paper. What if the power breaks down? This and many other questions had to be answered before the standards would satisfy the members of IMO.

This paper and the following two papers were presented at the Euronav 94 Conference organized by the DGON and the R1N and held in Dresden in June 1994.