In the mid-16th century the English began to expand their merchant and fighting navies to sail beyond the waters of north-west Europe. This necessitated mathematical navigation, charts, and written and illustrated sailing directions; all, from the 1580s, were embodied in the printed ‘waggoners’ of the Dutch and were used in translation by the English seamen.

1. INTRODUCTION. In his Presidential address last year J. E. D. Williams treated us to a most absorbing, largely philosophical review of the development of the science of navigation over the last five centuries. In discussing the profound and enduring influence of radio waves on air navigation over the last century he commended as of ‘transcending importance’ the ‘homing quality’ of the radio beam in which the accuracy increases as distance from the transmitter decreases. He illustrated this ‘homing quality’ with references to the radio range for en-route navigation and the instrument landing system (ILS) for guidance to the runway. But he went further and remarked ‘Automatic landings in regular airline service are an example of how a perceived potential of the homing quality of radio has drawn to navigation a whole range of diverse applied sciences including, in this case, information theory, the properties of semi-conductors and the theory of servomechanisms and control, among many others.’

This paper was presented at the 44th Annual Meeting of the US Institute of Navigation in Annapolis, June 1988.

Navigational systems are usually thought of in terms of locating vehicles and craft over a range of hundreds or thousands of miles. There are, however, applications where navigation systems with a range of a few miles and an accuracy of inches can be very useful. Farming is one of these applications and this paper identifies the specific operational aspects that can benefit. Precise navigation could facilitate a lowering of input costs by an estimated jo per cent on a western dryland farm.

1. INTRODUCTION. The object of open-ocean navigation is basically to find a ship's position. In coastal and confined waters, another dimension is added – the margins for errors are smaller, and actual ship handling must be integrated with the pure navigational disciplines. In restricted waters, the traditional philosophy of position fixing at intervals in terms of a point, e.g. cross-bearings, bearing and distance off a reference object, or latitude/longitude, is no longer a prime objective.

This paper, based on documentary records, attempts a brief, systematic investigation of the main characteristics of ancient Chinese sailing directions in terms of content and form as well as development. The evolution of Chinese sailing directions can be divided historically into the following periods and categories:

1. Non-written records.

2. Primitive written forms.

3. From non-quantitative description to quantitative description.

4. Quantitative description with charts,

5 . Charts aided by written descriptions.

In the course of his examination of these categories, the author analyses the most important sailing directions in Chinese history, and concludes that, Zheng He Hang Hai Tu (Zheng He's Nautical Charts) compiled in the first half of the fifteenth century, are not only the first illustrative sailing directions which do not rely on written directions but appear to be the first nautical chart collection for ocean-going sailing in history.

Finally, the author points out that, although western sailing directions have contributed greatly to navigational science and technology, the Chinese contribution to the development of sailing directions, deserves greater recognition.

This paper was presented at the RIN89 Conference on Orientation and Navigation – Birds, Humans and other Animals. The conference was held in Cardiff in 04 1989. The printed proceedings contain some 27 papers and are available by application to the Director. The price is £30 (RIN Members) or £35 (Non-Members).

This paper was presented at the RIN89 conference on Orientation and Navigation – Birds, Humans and other Animals held in Cardiff in April 1989.

1. INTRODUCTION. The American Global Positioning System (GPS/Navstar) and the USSR's Glonass are superb demonstrations of high technology but we should not forget that they were designed and implemented for a very different set of circumstances from that of the civil surveyor and navigator. Many of their features are not required for civil purposes and it is perfectly possible to get excellent results for many civil applications without the vast expenditure that went into those systems. This paper describes some of the ways in which it is proposed that satellites, not necessarily launched for the purpose, might be, and are being, exploited for civil navigation and location.

This paper was presented at an Ordinary Meeting of the Institute, held at the Royal Entomological Society, London, on Wednesday 20 April 1988.

The current method of artillery survey is reviewed and its limitations examined in the light of both the system error budget and the envisaged battlefield threat. The concept of the Automatic Gun Laying System (AGLS) is introduced as a means of enhancing the effectiveness and survivability of the self-propelled gun element through the application of modern inertial navigation (IN) technology. As a complement to this, the use of IN technology to provide a vehicle-mounted target observation capability is also presented. The paper describes a unified treatment of the artillery system, leading to the selection of the respective IN solutions, and concludes that a standard module is both appropriate and optimal. Environmental factors are discussed, together with the alternative sensors and systems considered. The paper concludes with brief comments on the status of inertial navigation within the military land area.

Around 1992 Navstar/GPS will become fully operational. Public access is then provided in the Standard Precision Service, SPS, at a reduced accuracy of 100 metres for 95 per cent of the fixes. The exclusively US military-operated system and the deliberately introduced degradation (SA, selective availability) of the attainable accuracy have some drawbacks for European navigation. Neither the probability density function of the error amplitude, nor its power spectral density function is known. So, using Navstar/GPS as a sole-means precise and reliable navigational aid for high-risk transports is not possible.

On 15 July 1988 in position 39° 08′ N., 58° 43′ W., some 470 miles south-east of Halifax, Nova Scotia, Jester was abandoned and her skipper taken off by the M/V Nilam, a 60000-ton bulk carrier bound for New York.

The boat was engaged in the single-handed transatlantic race from Plymouth to Newport, Rhode Island. The race, which started on 5 June, was Jester's eighth and her fourteenth transatlantic passage. The incident, a knockdown, occurred some 40 days out.

This paper is based on a presentation made at the IAIN International Navigation Congress held in Sydney, Australia, in February 1988.

The global positioning system (GPS) offers a new opportunity for the automation of aircraft landing systems. The position and velocity measurements provided by a state-of-the-art GPS receiver using the C/A code and working in a normal or differential mode (D-GPS) and aided by one or two ground-based PseudoLites (PLS), may be able to satisfy the landing accuracy requirements of the FA A.

This paper describes the design and simulation of an aircraft automatic landing system. Aircraft position and velocity are assumed to be measured using a (carrier-tracking) GPS receiver. The hypothesized capability is based on measurements taken at Stanford and elsewhere, using the Trimble 4000SX, five-channel receiver in an integrated-doppler-aiding mode. For some of the autopilot designs, either ground-based GPS transmitters (pseudolites) or a radar altimeter have also been incorporated.

Included in the landing simulations are wind shears and a gust model, creating realistic landing situations. The performances of the lateral and vertical displacements are presented with their 1σ r.m.s. estimation errors during the glide-slope and flare phases. Included are different wind conditions, GPS configurations and controllers. The results are compared with the FAA requirements for various categories of automatic landing systems.

1. INTRODUCTION. Very-low-frequency radio waves were used to implement the Omega navigation system because of their low attenuation (2–4 dB/1000 km) when propagating globally in the waveguide formed between the Earth and the ionosphere. However, it became apparent in the early seventies, throughout the period when the majority of the stations of the Omega network were commissioned, that VLF signals propagating over permafrost or glacial ice could suffer anomalously large attenuations, of greater than 20 dB/1000 km, especially during the daytime. In the Northern Hemisphere problems have arisen with the heavy attenuation of Omega signals propagating over the Greenland ice sheet. In particular a very bad region for Omega coverage occurs around Winnipeg in Canada (the ‘Winnipeg Hole’). In this area Omega North Dakota suffers from ‘near field’ effects, Omega Liberia is contaminated by trans-equatorial modal effects and Omega Norway is removed by the attenuation of its signals when crossing the Greenland ice-cap. There have even been discussions on the feasibility of constructing extra VLF transmitters in Canada to alleviate this problem.

The search for more efficient ship operation has increased over the last decade. One trend towards reducing operational costs is to conceive the wheelhouse as an operational centre for performing both navigational and supervisory tasks, such as monitoring the propulsion plant status and the condition of ship and cargo.

Under contract to the National Foundation for the Coordination of Maritime Research in The Netherlands, a study was conducted on the feasibility of a highly automated wheelhouse for single-handed navigation. In a series of simulation experiments, and by analysis, the effects on efficiency and safety of performance were investigated.

Results show that a careful function allocation can lead to an automated wheelhouse concept suitable for safe navigation in landfall conditions. Questions concerning the effects of monotonous watches on operator's alertness and the effects of the change in task structure on the operator's skill and interest in the job need further attention.

John Habberley is Research Leader at the College of Maritime Studies, Warsash, Hampshire, UK, to which the study was contracted by the Marine Directorate of the Department of Transport. Don Taylor is consultant to the project.

A number of factors need to be understood initially.

(1) Alignment is based upon the use of light, though not on being able to see where you are going!

(2) The theory relies upon three dimensional co-ordinate geometry.

(3) The knowledge that junction error will increase with distance, together with the commercial need to keep construction time short, normally means tunnelling from the ends towards a junction in the middle.

(4) Difficulties arise because of short baselines and no intermediate fixes.

(5) Terminology needs some explanation. Thus desired alignment is designed and then set out in the tunnel. Post-construction, a wriggle diagram is prepared and final alignment computed.

As the marine sextant is only useful to low-flying aircraft because of its reliance on the sea horizon (see Section 1), many earlier pioneers descended almost to sea level to take their sights; but as Alcock and Brown were the first to discover, it is often necessary to climb above the cloud in order to see the sky. Some pioneers used the horizon of stratocumulus cloud below, among them K. M. Grieve who, with Hawker, would have been the first across the Atlantic if radiator trouble had not made them the first survivors of a mid-Atlantic aeroplane ditching. As Grieve was so happy with his cloud horizon, disbelief must be suspended. Indeed, what has been claimed to be ‘the first real aeronautical sextant’, designed in 1919 by the same ingenious Capt T. Y. Baker RN who invented the Baker Navigating Machine (see Section 4 5), used a reflecting prism as an index mirror and two horizon prisms giving a view of both the back and front horizons. Provided both cloud horizons were equally depressed below the true horizontal plane, the instrument gave the true altitude of the body observed.

Air traffic control (ATC) makes extensive use of computer technology in subordinate roles for processing flight-plan and radar data and for message switching. It is usual to stress that such computers are aids to human controllers who take the decisions. It can, however, be argued that computers are, in fact, already encroaching on the decision-taking processes. The SSR plot extractor, for example, produces a censored summary which amounts to only a few per cent of the torrent of radar data from which it is derived. This summary is then subjected to code conversion and coordinate transformation before it reaches the controllers who cannot refer back to the data sources. Once computer-processing has been introduced, the issue is no longer whether a computer may take some of the decisions involved in ATC, but merely the extent of the authority it can exercise.

This paper puts forward a case for more precise navigation at sea. It commences by briefly outlining existing and forthcoming navigation aids. The integration of marine navigation systems, and in particular the use of Kalman filtering is then discussed. After outlining the developments in the aerospace industries, the authors suggest why marine developments have not been so rapid as those in the air. The idea of automatic collision avoidance is also raised and a method for tracking radar targets discussed. Finally, the authors survey marine applications of Kalman filtering techniques, including some references to their own work, and assess the need for further research and development.