A developing theme of long-haul operations is the desire for non-stop services between large centres of population and business areas. The delivery of modern aircraft with such long-range capability is evidence of airline commercial objectives and plainly demands improvements to the way in which air traffic is managed. There is now an opportunity to change radically the way in which over-flights are managed and operated. It is imperative to increase capacity in step with demand as it is the limitation in capacity that is fast limiting an expansion of the business.

Farmers are having to gather increasing amounts of data on their soils and crops. Precision agriculture – the targeting of inputs such as fertilizers and herbicides according to locally determined (‘metre-by-metre’) requirements – is based on a knowledge of the spatial variation of soil and crop parameters across a field. The data has to be spatially located and GPS is an effective way of doing this. A backpack data logging system with GPS position tagging is described which has been designed to aid a fanner in the manual collection of data.

This paper describes one of the key features of the JTIDS/Link 16 tactical data-link, namely its relative navigation facility. A brief overview of the general features of the JTIDS system is given to provide the necessary background to the navigation aspects, and some mention is made of the message-exchange facilities. The main part of the paper describes how the JTIDS system provides the capability to perform accurate navigation, and discusses the basic principles of its operation. Some applications of the navigation function which enhance operational effectiveness are then described. The following topics are covered:

(ii) JTIDS Architecture

(i) Definition of JTIDS/Link 16

(iii) Principles of Relative Navigation

(iv) Source Selection

(v) The Kalman Filter

(vi) Time Synchronization

(vii) The Use of Relative Navigation

(viii) The Relative Grid

Recent statistics are reviewed with regard to deficiencies in standards of seaworthiness often resulting in detention as noted from surveys worldwide. Recent ship loss statistics are analysed, the subject of ownership of Flag of Convenience (FOC) vessels is addressed and FOC registry related to vessel loss data. The increasing age of the world fleets is noted as replacement orders for new hulls have dwindled. Crew costs are discussed and considered in relation to economics and safety of operation. Comparison is made on ship safety between routed and non-routed vessels. Improvements in weather routeing services and safety are noted as a result of employing automated systems.

This paper presents the research for the development of a new travel aid to increase the independent mobility of blind and elderly travellers. This aid will build on the technologies of geographical information systems (GIS) and the Global Positioning System (GPS). The MOBIC Travel Aid (MOTA) consists of two interrelated components: the MOBIC Pre-journey System (MOPS) to assist users in planning journeys and the MOBIC Outdoor System (MOODS) to execute these plans by providing users with orientation and navigation assistance during journeys. The MOBIC travel aid is complementary to primary mobility aids such as the long cane or guide dog. Results of a study of user requirements are presented and their implications for the initial design of the system are discussed.

Surveys reveal that walking is by far the most popular leisure activity in the UK, and still growing. Each year some half a billion ‘leisure day visits’ specifically involve walking in the countryside and over 60 percent of the adult population claim to participate in walking as a ‘sport’. These statistics serve to confirm our own experience that enormous numbers of walkers go out to enjoy the countryside, but when we say ‘walker’ we include Sunday afternoon strollers in Windsor Great Park, a rambling group following the coastal path in Dorset, strong fit youths doing the Pennine Way, or Munro baggers in the Scottish highlands. Walkers come in many a hue.

Knowledge of the statistics of aircraft vertical speeds is important both for the construction of realistic traffic simulators and for the development of trajectory prediction tools for use in future air traffic control (ATC) systems. This paper reports on the analysis of radar data recordings for nearly 10000 civil flights on airways. Results are presented for the means and spreads of vertical speeds as functions of altitude. Evidence is presented that roughly half of the observed spreads arise from fluctuations within each aircraft's trajectory, as opposed to variation from one aircraft to another. A simple procedure is proposed for simulating vertical speed data which has statistics similar to those obtained from the radar recordings. Some consequences of the results for the development of trajectory prediction tools for use in future ATC systems are discussed. The results suggest that the provision of accurate trajectory prediction tools is not as straightforward as it might at first appear to be.

Orientation within orienteering is dependent on the use of two basic strategies; that is, either a compass or Magnetic-North-based strategy, which relies on the use of one set of information; or the use of a map and landmark-based strategy which relies on the use of at least two sets of information. Walsh and found that, when given the choice, young children use the compass-based strategy when following complex potentially disorientating routes.

The efficacy of these two basic orientation strategies was investigated within three different orienteering environments: (1) a familiar known environment; (2) a familiar unknown environment and (3) an unfamiliar unknown environment.

Subjects, age range from 9 to 10·5 years, completed an appropriate orienteering route in each of the environments. Individual mini-cassette recorders and tie-pin microphones were used to record data using a ‘think aloud’ technique as subjects followed their selected routes. Transcripts of the taped data produced a total number of uttered statements for each subject within each environment. A qualitative analysis of these statements identified the following groups of statements expressed as percentages of the total number of statements (as reported by Thorndyke and Stasz): (a) Orientation statements; (b) Relocation or error correction statements; (c) Statements about distractions; (d) Self-efficacy statements.

There was a higher reported use of the compass-based strategy for orientation within the familiar known environment which supported the earlier findings of Walsh and Martland. Although the percentage of compass-based orientation statements was smaller in the familiar unknown and the unfamiliar unknown environments, there was a pattern in the use of orientation strategies within these two environments. Typically, the compass-based orientation strategy was used for initial orientation at the beginning of the route and at the pre-defined control points along the route, whilst the landmark and map-based strategy was used as a means of maintaining and reinforcing orientation within the route. Relocation statements typically reported an awareness of disorientation and were generally followed by attempts to reorientate. Whilst none of the subjects used relocation statements within the familiar known environment, relocation statements were used within the familiar unknown and the unfamiliar unknown environments.

This evidence suggests that both orientation strategies are used in orienteering routes, but that each strategy is used selectively depending on the environment. These findings clearly have implications for the sport of orienteering – particularly the introduction of basic skills to young performers. They support the argument that is essential to introduce the map and compass simultaneously and that relocation and orientation skills should be coached concurrently.

Recent evidence has shown that the effect of a ship moving in shallow water and the resultant squat are not well understood. This paper reviews the general problem of a ship in shallow water and illustrates the corresponding resistance, trim and sinkage at both sub-critical and also at super-critical speeds.

The paper then reviews the various methods of predicting the squat of a ship in shallow water in the sub-critical range, which is applicable to most ships. It is suggested that the simple rule-of-thumb methods are, at best, unreliable and the paper gives examples of empirical methods which have been tested against various sets of data and seem to give more representative answers. A summary of the notation used is given at the end of the paper.

The advanced ship's operational control system (ASOCS), as described in this paper, has been developed as an important part of a one man bridge system (OMBS). Systems of this kind are expected to become an essential feature as ship navigational systems develop in the future. This paper systematically analyses the structure and composition of ASOCS and proposes a type of computer network for the system. The functions of ASOCS are analysed with OMBS research particularly in mind.

On 14 September 1494, Christopher Columbus observed a lunar eclipse while at the island of Saona near the eastern tip of Hispaniola. He later recorded in his Libro de las Profecias that, from his timing of the eclipse, he determined his longitude to be ‘five hours and more than one half’west of Cape San Vicente. His actual longitude was three hours and 59 minutes west of Cape San Vicente, so Columbus was off by over an hour and a half, some 23 degrees of longitude.

About ten years ago this author wrote the software for a suite of navigation programmes which was resident in a small hand-held computer. In the course of this work it became apparent that the standard text books of navigation were perpetuating a flawed method of calculating rhumb lines on the Earth considered as an oblate spheroid. On further investigation it became apparent that these incorrect methods were being used in programming a number of calculator/computers and satellite navigation receivers. Although the discrepancies were not large, it was disquieting to compare the results of the same rhumb line calculations from a number of such devices and find variations of some miles when the output was given, and therefore purported to be accurate, to a tenth of a mile in distance and/or a tenth of a minute of arc in position. The problem has been highlighted in the past and the references at the end of this show that a number of methods have been proposed for the amelioration of this problem. This paper summarizes formulae that the author recommends should be used for accurate solutions. Most of these may be found in standard geodetic text books, such as, but also provided are new formulae and schemes of solution which are suitable for use with computers or tables. The latter also take into account situations when a near-indeterminate solution may arise. Some examples are provided in an appendix which demonstrate the methods. The data for these problems do not refer to actual terrestrial situations but have been selected for illustrative purposes only. Practising ships' navigators will find the methods described in detail in this paper to be directly applicable to their work and also they should find ready acceptance because they are similar to current practice. In none of the references cited at the end of this paper has the practical task of calculating, using either a computer or tabular techniques, been addressed.