The next issue of the Journal, which starts the fortieth volume, will have a new Editor, Professor J. F. Kemp, and a new publisher, Oxford University Press.

This paper was presented at a seminar entitled a European Concerted Approach to Vessel Traffic Services for Safe Navigation – EEC Project COST-301, sponsored jointly by the Institute's Netherlands branch and the Royal Institute of Engineers, Delft University of Technology and the Netherlands Directorate General for Shipping and Maritime Affairs held in Delft on 20 January 1986. It was published under the auspices of the European Environmental Bureau, an independent coalition body of leading environmental organizations in all the European Economic Community countries (with a total membership of over 10 million). The paper, of which the following is a condensed version, seeks to comment on the implications for environmental protection of the various COST-301 research programmes, and to assess the contribution which the findings resulting from them may make to future European coastal state policy and international measures.

Aline De Bièvre is with the European Environmental Bureau and John Kemp is Professor Emeritus at the City of London Polytechnic.

Knowledge of surface currents is of fundamental importance in many diverse marine activities; for example in navigation, offshore engineering and operations, and in the prediction and monitoring of the movement of pollutants. In those areas of scientific research directed towards improved understanding of climate, and towards the modelling and prediction of currents, studies of exchanges of heat and momentum between atmosphere and ocean also require detailed knowledge of mean and fluctuating components of near-surface flow.

Until 1950 the largest ships of the merchant fleet and the major warships had the same draught, about 12 m. Hydrographic offices concentrated their efforts on those areas likely to contain hazards to such vessels, that is to say the areas extending from the shallow waters to the 20 m contour line. The maximum draught of warships has been stable whereas the draught of merchant vessels increased considerably up to 30 m in recent years. A VLCC may risk grounding after having crossed the 30 m line or even the 40 m line. Nowadays, the part of the continental shelf which is best known is the part in which the largest vessels are unable to operate.

This paper describes modern autopilots for ships. The development of modern optimal and adaptive control theories, together with the availability of inexpensive and fast digital computer systems, makes possible the design of more sophisticated controllers, which achieve better steering and save fuel. Autopilots which simultaneously control the yaw and roll motions are now being developed. In the near future it is to be expected that advanced track-prediction and track-keeping systems will facilitate the navigation and further contribute to fuel savings. The paper was presented at a Workshop held by the Netherlands branch of the Institute on 21 February 1986.

A number of studies have been carried out by consultants on behalf of the General Lighthouse Authorities (GLA) to assess the effectiveness of aids to navigation systems and to study the effects of changes to these systems. The usefulness of graphical representation of aids to navigation systems was appreciated and a program was developed for a desktop computer, combining graphics with numerical analysis of effectiveness. The program has been used in two studies for the GLAS, the results of which are used here to illustrate the techniques involved.

The annual total losses of trading ships as a result of collision and wreck were considered in a previous paper for the purposes of comparing the safety records of different flag groups. Losses up to the year 1979 were included in the tables. In order to assess whether there has been an improvement, the losses for the 5-year period 1980–4 will now be considered and compared with losses in previous years.

The orbits of navigation satellites have to be determined very precisely. The Transit broadcast (predicted) ephemeris, which is computed by the US Navy Astronautics Group, has an estimated orbital positional accuracy of the order of 25 m in each direction. By contrast, the precise (post-mission) ephemeris, which is determined by the US Defense Mapping Agency, from tracking data collected by the global TRANET network, reaches accuracies of the order of 10 m. These orbital precisions affect the navigation and (static) positioning accuracies which can be achieved by users of the system. The same is true of the GPS system which will become fully operational some time during 1988—89. However, unlike Transit, GPS will allow quasi-instantaneous absolute positioning (i.e. real-time navigation) as well as very high relative positioning accuracies. The latter will be obtained by using special operational and processing techniques (e.g. ‘differential GPS’ and ‘GPS interferometry’).

Whereas the proper object of all commercial transportation is profit-making, the navigational objectives of taxis and of airliners differ remarkably. In airlines navigation only affects product quality and operating costs but in taxis the revenue (the fare on the meter) is a function of the navigation. Regularity of service is meaningless to taxis whereas regularity of schedule keeping is an imperative of airline navigation because it is only possible to offer air fares a full order lower than taxi fares on aeroplanes costing up to $200,000 a seat by achieving high equipment utilization. Many taxi drivers hire their cabs at a weekly rate which includes maintenance and repair but not fuel. They therefore have a direct interest in the cost of fuel but not in wear and tear of machinery. Finally, taxi drivers are self-employed businessman whose income depends entirely on their navigational skills.

Inertial navigation systems represent the ideal in automatic navigation. They operate entirely without external assistance, other than information as to their starting conditions, which makes them of great interest to both military and civil operators.

Mathematical collision risk models, e.g. the Reich (1966) model, may be useful for evaluating the safety of air traffic control systems. The model requires parameters associated with the navigational errors of aircraft. Among navigational errors the distribution of height-keeping errors (HKE) is of great interest for evaluating the feasibility of reducing the current 2000 ft vertical separation standard above flight level 290 (29000 ft). The distribution is closely related to the probability of vertical overlap which is a key parameter of the collision risk model.

It is generally acknowledged that the present terrestrial radio-navigation facilities are in need of updating. Furthermore, satellite navigation offers great potential benefits to all classes of user. One of the factors to be taken into account is cost, and with this in mind it would be useful to establish how much the present spectrum of terrestrial radio-navigation aids itself is costing and what it provides for the money. This is a difficult task which has been attempted before. Each attempt makes a dent in the armour of impenetrability that is inherent in the problem. This paper adopts a fresh approach which it is hoped may make a dent slightly greater than some of the others.

‘The Protected Volume of Airspace Generated by an Airborne Collision Avoidance System’ by R. L. Ford published in Vol. 39, No. 2, May 1986.

On p. 151 the expression on line 10 should read: 2Zt/cos φ: and in the following line: as φ approaches π/2. Equation (16) on p. 157 should read: