The aim of the Duke of Edinburgh's lecture is to extend the horizons J. of navigational interest. I shall try to show how modern scientific methods are greatly increasing our understanding of how the oceans themselves work, and, at the same time, do all I can to maintain that this new knowledge is not just a matter of curiosity. If vigorously developed it will be of much practical use to seamen, and of great benefit to us all. The time is opportune. Scientifically inclined nations recently have been making organized all-round exploration of the human environment. As well as major Antarctic operations, and the rush to Space, there is growing realization that the oceans are coming within our grasp for major technical exploitation.

The Safety of Life at Sea Conference, 1960, recognized the special danger of the concentration of maritime traffic in converging areas and entrusted shipping companies with the responsibility of establishing the channels to be followed in these areas. The three Institutes of Navigation may be helpful to the companies in this respect through the competence and prestige of their special working groups. The problem consists in defining one-way channels and cross-overs for different streams of traffic. In entrusting this responsibility to the companies, the London conference implicitly agreed that the organization of converging areas was a simple application of the International Regulations for Preventing Collisions at Sea to the particular conditions of each area.

In converging areas ships will remain entirely and solely subject to the Collision Regulations. Agreements on the channels to be used will be covered by Rule 29 which refers to the ‘Ordinary Practice of Seamen’.

A revision of the North Atlantic Track Agreement would make it possible to form a larger group of subscribing companies. The existing tracks could be simplified and the danger of convergence on certain channels avoided by modifying the double landfall at Fastnet and Bishop and by moving certain junctions. This could be done without unduly lengthening the channels. One might also replace the concept of fixed channels by the more liberal one of protected channels, which one might call ‘Naviroutes’.

Ships wishing to follow these would benefit from increased safety by the use of certain simple rules, which may be summarized as follows:

A neutral zone, varying in size according to the region, of the blue-line type proposed by Oudet and Poll would separate traffic going in opposite directions. In good visibility ships crossing a ‘Naviroute’ would do so at an angle of more than thirty degrees; in fog ships would cross a ‘Naviroute’ at right angles and at low speed. Each of these rules is dictated by commonsense to every seaman with experience of crossing busy shipping channels.

The paper examines in particular the possibilities of using leader cables for establishing traffic lanes at sea. A brief history of the leader cable is given, followed by discussion of the components and variables in the system such as the cable itself, the energizing frequency and detection and indicating devices. The application of leader cables in the context of modern navigational conditions is then examined. An appendix gives a valuable list of some of the more important references on leader cables.

The paper discusses the measure of control to be exercised by the Port Authority in a Port Entrance Area where shore radar enables tracks to be made of all ships present. The problem becomes acute where great numbers of ships are trying to enter and leave in restricted visibility, creating danger and confusion.

In a previous paper presented at the conference, Commandant R. Betton, Captain of the Port of Le Havre, suggested that it was perfectly possible for shore-based guidance radars to be used to reduce collision risks at the entrances to harbours, provided this supplementary function is precisely denned in terms of how much authority harbour administrations can exercise over ships outside the harbour. Betton stipulated that any control should only be exercised by experienced seamen and that they should not have the right to interfere in manœuvres for which masters should have sole responsibility.

Most collisions on inland waterways occur in daylight and in good visibility and it is here there is most scope for improvement. Elaborate traffic control schemes such as that planned for the Panama Canal may not be suitable on European rivers where the density of shipping is very high and the nature of the traffic mixed. Local control may be feasible, but between control areas vessels will have to rely on self-contained aids, ship-to-ship communications and local navigational rules to avoid collision. The congestion of traffic, particularly at Customs clearance points, must be relieved.

The paper discusses various aids to river-radar navigation, which are making fundamental changes in the methods on European inland waters.

The Panama Canal Company's Marine Traffic Control is being designed primarily to minimize ships' average transit-time and obtain optimum use of Canal facilities, but it also includes features contributing to collision prevention. It prepares an operation schedule consistent with the number and characteristics of ships that are in transit and with operating conditions. Actual operation is continuously monitored and signals currently displayed to pilots to facilitate close adherence to the schedule. If the contemplated schedule is cancelled, as by trouble in locks or sudden periods of poor visibility, re-scheduling is rapidly formed and signals transmitted to pilots in conformity with the new schedule.

The system's contribution to collision prevention includes elimination of several hazardous situations: (a) Undue crowding of traffic; (b) Lock-entrance stand-off delays due to untimely ship arrival, during which ship handling is difficult; (c) Meets or overtakes at potentially hazardous locations.

Further, when approaching a bend on which other ships would not be visible and at which the meet would be hazardous, a pilot is advised of the number of ships which will be round the bend before he reaches it. Also indicated is the number of meets due to occur immediately beyond the bend, a distance through which the manœuvrability of his ship would be affected by the manner in which he rounds the bend. The automatically operating system is based on transmission of data comprising ships' identities and locations to a central control point where the data is analysed by an electronic computer and from which advisory signals are automatically transmitted back to the ships.

Collision-avoidance devices are all based on the use of either electromagnetic or acoustic waves, although the former (i.e. radar) is of particular interest for this purpose.

After reviewing briefly the fundamental theory which underlies all methods of detecting, locating and recognizing a distant target, reference is made to the successful development, in the Electrical Engineering Department of the University of Birmingham, of a narrow-band sector-scanning sonar system employing a multiplicative array to give improved target resolution. It has been demonstrated experimentally that the same principle can be applied to obtain a sector-scanning radar system capable of scanning rates as high as one million scans per second, which has applications for airfield surveillance radar. Attention is now being directed to the possibility of using wide-band signals, either to improve target detection and location for an array of a given size or to obtain additional information about the nature and behaviour of the radar target itself. Two possible methods of using wide-band signals are described.

Separation of aircraft in terminal areas is made difficult by the convergence of tracks, continual changes of height, and traffic density. The application of longitudinal separation is too restrictive at busy aerodromes. Vertical separation is suited to the approach phase, but has limitations in the departure phase. The most useful form of separation is lateral, although it is often difficult to apply. The difficulties arise from organizational rather than operational causes and efforts to overcome them can be most rewarding.

Other difficulties of a terminal area arise from the conflicting patterns of adjacent aerodromes, the mixing of terminal and overflying traffic, and the mixing of departing and arriving traffic. Lateral separation can assist in all these problems.

In areas of sufficiently high traffic density, air traffic control in some form will always be the primary mode of ensuring aircraft separation. Any traffic control system is concerned with separating aircraft in the future; therefore, the nominal separation criteria are determined by the accuracy of prediction of future movement of the aircraft and by the ability of the control system to correlate flight path predictions. The utilization of an airspace of a given capacity is determined by the distribution or flow of traffic.

The accuracy of prediction depends on track-keeping and maintenance of planned ground speed. Since improvements in track-keeping will be limited for some time by past I.C.A.O. decisions on short-range navigation aids, attention is directed in this paper to maintenance of flight-planned ground speed. The effect of this on the operating cost of a modern jet airliner is examined and compared with the cost of flying at minimum cost mach number at a less than optimum altitude. It is concluded that in a crowded airspace, speed maintenance is preferable in short-range operations.

The increase in space utilization by flow control is illustrated for a simple model, showing that speed control by A.T.C. increases utilization of a space capacity, which has already been increased by speed maintenance.

The main meteorological features of the atmosphere from 50,000 to 70,000 ft. which are likely to be of importance to supersonic aircraft, are the ‘polar-night westerlies’ and the abrupt rises in temperature which take place in late winter in latitudes polewards of 50° or 60°.

The polar-night westerlies blow between 50° and 70° latitude and reach high velocities, increasing with height, from 60,000 ft. during the winter months; towards.the end of the polar night there is often a sudden rise (perhaps as much as 40° C.) at about 85,000 ft., which spreads downwards and is eventually associated with the termination of the polar-night westerlies.

The increase of speed of supersonic aircraft, as well as the decrease of variability of the wind with time at heights above 50,000 ft., have remarkable effects on the punctuality of arrival of aircraft. For instance, on the route from London to New York, the probable error due to wind in arrival time of a 1500-kt. aircraft at 50,000 or 60,000 ft. is about half a minute. This is in contrast with a probable error of ten to fifteen minutes for a 400-kt. aircraft flying at 30,000 ft.

This paper describes an experimental system of representing the reading on an altimeter in the form of a digital code, and controlling the standard I.C.A.O. secondary surveillance radar transponder to give a corresponding pulse pattern.

Different code arrangements are examined and their capacity noted. A possible use of the system in collision avoidance is suggested for use outside areas of close air traffic control. This use would require little additional equipment.

In the April 1961 number of the Meteorological Magazine, A. F. Crossley discusses Hail in Relation to the Risk of Encounters in Flight. Since it is probable that the Meteorological Magazine does not readily fall into the hands of members of the Institute of Navigation the following brief summary may be of interest, though of course anyone wishing to pursue the subject further should refer to Crossley's original paper and the numerous references therein.

Recent articles in this Journal will have suggested that there is a conflict between certain mathematicians and certain mariners on the subject of the efficacy of the Collision Regulations. The controversy is really philosophic rather than mathematical and, although it would never be suggested that the mathematical system we have seen is anything but flawless in isolation, there are grave doubts that it would work, even on a planet composed solely of deep water and supporting ships staffed only with mathematicians, having collision avoidance as their single preoccupation.

In June 1958 the writer submitted to the Ministry of Aviation a paper, summarized below, on the avoidance of collisions in the air. The views expressed are his own and not necessarily those of the Company for which he works.

1. The rules of the air should recognize that the information available to the pilot, whether obtained by visual or ‘electronic’ means, is likely to be limited by the following:

(a) the pilot's ‘field of view’ is at most ± 90° in azimuth and some ± 20° in elevation relative to his aircraft heading.

(b) a collision course can be recognized, but not the heading, course or speed of the other aircraft.

Whilst steaming westwards at night along the coast of South Africa, echoes were received on the radar screen that gave the impression the vessel was about twelve miles off the coast. At the time, the vessel was about thirty miles S. by W. of Seal Point.

The radar set, a Decca Mk. 12, was operating on the twenty-five mile range. It was receiving strong echoes from a sighted ship seven miles away on the port quarter. The set had been switched on to clear an unlit buoy fitted with a radar reflector. The position of the buoy was about ten miles WSW. of the vessel's position.