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.

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 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.

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.

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.

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 describes preliminary studies towards a navigational Knowledge-based System currently in progress within the School of Engineering and Technology Management at Liverpool Polytechnic.

In this paper, methods and formulas for testing ARPA (Automatic Radar Plotting Aid) equipment according to IMO requirements are developed. The International Maritime Organization (IMO) and International Electrotechnical Commission (IEC) requirements for tracking accuracy are also discussed.

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

The following is an assessment of Area Navigation Systems, or RNAV, as they apply to regional aviation.

Regional aviation, in this context, refers to that third sector of the airline industry which concentrates on short haul, high frequency, so-called ‘hub and spoke’ operations. Now amounting to over j per cent all airline passenger traffic, regional operations by their nature have more to gain from the use of RNAV than any other segment of the airline business. In particular we look at how RNAV systems provide business opportunities to regional operators, not only to manage aircraft more effectively, but in the process to improve a firm's viability.

Hairawa in the Journal made the statement that there is no easy method of calculating the length of a geodesic line on the surface of a spheroid and this is true. Nevertheless, it is the purpose here to attempt to devise a method and then to leave it to the reader to judge whether or not the amount of work involved justifies the method as an alternative to the correction methods of Andoyer and Lambert and to the work of Hairawa himself.

In situations where the use of a magnetic compass has disadvantages, it is sometimes possible to use successfully a suncompass. All known suncompasses use the clock time. This paper introduces a method of orientation which does not use clock time and which surpasses the accuracy and usefulness of the Cole suncompass.

de Wit has produced an analysis of the apparent spontaneous yaw of a ship when undergoing combined rolling and pitching. This analysis produces a set of four first-order simultaneous differential equations which govern the motion. In de Wit the numerical solutions of these equations for a couple of representative examples are given, as well as the corresponding analytical solutions to the linearized equations. In this communication it is shown how two of the four equations can be solved analytically; these solutions can be used to obtain approximate analytical solutions to the remaining two equations.