bluuebunny/crossref_metadata_2025 huggingface dataset:
The Accurate Determination of Aircraft Altitude
Authors: Warner J.
Published: January 2010

A method of obtaining aircraft altitude to within 50 feet at altitudes of 10,000 to 20,000 feet is described. This accuracy is necessary in a few special cases. The method consists of determining the height of a pressure level at some convenient point by radar or other means, and then calculating from a knowledge of the wind vector the change of height of this pressure level between the check point and the point at which an accurate altitude is required. The limitations of alternative methods of height finding, such as the use of an aneroid altimeter corrected for temperature at the upper level, are discussed.

For most purposes the aircraft type aneroid altimeter gives a sufficiently accurate indication of height, provided corrections are made for the temperature at flight level. In the application of radar to topographical surveying, however, it is necessary to know the altitude of the aircraft used in the measurement to within 50 feet when flying at heights of 10,000 to 20,000 feet. This can be achieved only by special techniques. The method here outlined has been used extensively during investigations into the use of radar for surveying. It is simple and appears to give satisfactory results.
Equivalent Head Winds on Air Routes
Authors: Crossley A. F.
Published: January 2010

1. Introduction. A detailed paper describing the theory and calculation of equivalent head winds on air routes has been prepared by J. S. Sawyer and is being published as a Meteorological Report. The present paper is a simplified account which draws largely on Mr. Sawyer's paper.

When regular air services over a route are being planned, the wind at the chosen level of flight is an important factor. From the long term point of view, aircraft require to be designed so as to operate economically against adverse winds, if not on all occasions at least on all but a small percentage of occasions; for example, British Overseas Airways Corporation usually specify an 85% regularity of operation as a minimum. Similarly, for short term planning, wind information is necessary for the computations regarding the averages and extremes of fuel consumption, payload, time of flight, and so on. The aircraft operator consequently requires to know the frequency distribution of winds on any given route at any time of the year.
Jet Streams and their Importance to Air Navigation
Authors: Durst C. S. , Davis N. E.
Published: January 2010

Jet streams are fast moving air streams which appear at times in the levels between 15,000 and 40,000 feet; they are located in the tropical air above the polar front. In this paper examples are given and certain occasions are noted on which they have seriously influenced air navigation.

Early in 1948 when a few charts of the 225 mb. level were drawn to show temperature variations over an air route it was noticed that a very strong stream of air was seen along the line where the tropopause appeared to cut that level. This stream seemed of very considerable length and little width.
Hyperbolic Projections
Authors: Fennessy E.
Published: January 2010

The introduction of radio aids to navigation of the hyperbolic type, such as Decca, Gee and Loran, resulted in the need for special charts. These charts, which are usually of the scale and projection appropriate to the occasion, have overprinted on them red, green and purple lattice lines, representing the families of confocal hyperbolae drawn with respect to the Master and Slaves of the radio system. The production of these lattice charts was extensively developed during the war, both in Great Britain and the U.S.A. To provide the mariner with satisfactory marine charts for use with the English Decca Chain, the Hydrographer of the Navy has latticed all the principal coastal charts of England and Wales, and the Danish Hydrographer has similarly latticed the Danish coastal charts.
Magnetic Compass Problems— A Fresh Approach
Authors: Harvey G. N.
Published: January 2010

This paper describes a number of proposals concerning the correction of the errors of magnetic compasses. The first proposal concerns the correction, by means of special soft iron correctors, of the deviating effects of both vertically and horizontally induced magnetization.

A scheme for removing constant error without having to use algebraic addition or even having to record the existing deviations is next described.

A scheme is then suggested whereby, provided no constant deviation is present, a compass may be corrected for the effects of permanent magnetism in four operations, each of which consists of the complete removal of deviation on a particular heading by a particular corrector.

Possibilities of putting compasses below decks without seriously affecting their performance are also discussed; these particular suggestions cannot apply to merchant ships in which magnetic cargo is being transported. Suggestions are also made of correcting the compass by modifying the disposition of the magnetic material in the bridge structure instead of by adding a corrector to the compass binnacle.

Finally, a scheme is introduced to maintain an aeroplane compass mounting parallel to the surface of the Earth during a level turn by using the centrifugal force due to the turn.

This paper puts forward five separate suggestions concerned with the correction and siting of magnetic compasses. The suggestions are unrelated to each other except in the fact that they have all resulted from viewing the problems from a deliberately unconventional standpoint. Some of the solutions proposed may be of interest to those concerned with magnetic compasses in ships, aircraft and vehicles.
The Influence of Echo Sounding
Authors: Hughes A. J.
Published: January 2010

Throughout the history of marine navigation it has been recognized by seamen that soundings of the sea bed are a most natural and valuable aid to safe passages. Yet it is probably true to say that the methods of obtaining such soundings and for recording and using the information so obtained remained relatively primitive for longer than any of the other arts or systems used by seamen.

Records can be found which indicate that the earliest navigators used poles or lines and plummets to measure the depths of water on the coasts and in the rivers. An example of the use of soundings by Phoenician seamen is recorded by Strabo, who relates that the captain of a Phoenician ship on a voyage to the Casseterides for tin thought himself too closely followed by a Roman ship and deliberately sought a shoal which he knew of on which to run his vessel to avoid capture and the loss of his precious secrets. Then Hanno, the famous Carthaginian admiral of about 500 B.C., at his furthest point south on the West Coast of Africa, outlined the contours of the River Niger, and the Greek admiral Nearchus at the same time made his voyage from the Indus to the Euphrates by soundings in the rivers and on the coast.
The Birth of the Compass
Authors: May W. E.
Published: January 2010

It seems probable that the magnetic compass, the mariner's compass as it is often called, first made its appearance at some time between the tenth and twelfth centuries A.D. Attempts have been made to prove that the compass was in existence earlier, and that some of the early voyages could not possibly have been performed without its help; but there is no evidence to support this contention and a certain amount to show that other methods were used.

Again, it has been suggested that some obscure remarks by certain classical writers could be explained if the author were assumed to be describing the use of a compass, whilst having only the haziest notion of what it was. Among such is the legend of Abaris, the Hyperborean priest, who visited Greece, some say from Britain, many centuries B.C., and had with him a mysterious arrow which showed him the way. If we cut out the fancies of some writers who credited him with the possession of a kind of aircraft (capable of supersonic speeds), it is not difficult to imagine that the arrow may have been a magnetized needle. The difficulty is in understanding how no one down the centuries which followed came to write of the compass. There is, of course, little doubt that much scientific knowledge was possessed by the ancient priestly cults and the knowledge of the compass may have been kept secret for their own ends. If the great library of Alexandria had not been destroyed we might have had the answer to the riddle; but perhaps there is none and the whole tale of Abaris is a fabrication.
Radar and the Rule of the Road at Sea
Authors: Wylie F. J.
Published: January 2010

The effect of radar on the application of the Rule of the Road at Sea has been given attention in several papers and discussions in recent months. Deductions on their relationship have been attempted, and already judgements have been delivered in the courts of this and other countries which take account of the installation of radar in one or both of the parties to a collision. The suggestion has been seen that guidance to mariners concerning their actions and responsibilities when radar is fitted must await the development of case law. This development will be a lengthy and probably painful process and the object of this paper is to discuss the possibility of establishing principles which would enable the great potential value and legitimate application of radar to be established without waiting for casualties.
An Elizabethan Compass Maker
Authors: Taylor E. G. R.
Published: January 2010

As between the scholar and the technician, the armchair theorist and the practical man, the antagonism is as old as civilization itself. In Queen Elizabeth's days the gentleman born was the only gentleman, however ignorant, while learning was the preserve of the universities; the practical man was a mere ‘mechanician’. But there was some liberal thinking, common-sense thinking, even in those days, and one Gabriel Harvey, a well-known literary man and controversialist, spoke up boldly for the technicians. Even though they had heard no university lectures, he said, and were deficient in book-learning, it would be a bold man who would despise such expert practitioners as Humfrey Cole, the mathematical instrument maker, William Bourne, the naval gunner, Matthew Baker, the shipwright, John Shute, the architect, John Hester, the chemist, and Robert Norman, the hydrographer and compass maker. No fewer than four out of the six notable men he named were doing work that was relevant to the advancement of the navy and navigation. They were at the height of their powers in the decade preceding the defeat of the Spanish Armada, a coincidence which cannot be without significance.
An Aircraft Approach Procedure: Some tests with aircraft using Distance Measuring Equipment and the Multiple Track Radar Range
Authors: Downes J. G.
Published: January 2010

This paper describes tests of an approach procedure in which aircraft approach the airport on a radial track, circle the airport on an orbit and finally approach to land on another radial track in line with the runway. Ninety-six approaches were made with a representative selection of airline pilots in an aircraft fitted with the Australian Distance Measuring and Multiple Track Range Equipment.

The flight tests provide information as to the accuracy with which pilots can follow a set track, both for track accuracy and turning, when provided with adequate navigation aids. The average time for the particular procedure used was 18 minutes, and 90% of all times were within ±1 minute of the average. Maximum departures from the correct track occurred during orbiting where the average track was 0·2 mile inside the nominal orbit, and in 90% of approaches the departure did not exceed ±0·8 mile. Detailed analysis of the turns is also given in which it is shown that, on the average, turns occupy ¾ minute instead of the ½ minute required for a correctly executed Rate 1 turn.
Navigation in High Speed Flight
Authors: Anderson E. W.
Published: January 2010

The history of mechanical transport has been one of increasing speeds and there seems to be little doubt that air transport will follow this pattern. To the passenger, increased speeds mean a saving of time, and time is money. To the operator, increased speeds mean more flights per week and therefore greater earning capacity for his aircraft. This year indeed has been marked by the appearance of the four-jet air liner, the forerunner of the four hundred knot air transport.
Aircraft Radio Altimeters
Authors: Sharpe B. A.
Published: January 2010

The necessity for an accurate instrument to indicate the height of an aircraft above the ground over which it is flying at any instant has long been recognized and a variety of types have been suggested.
Some Profiles for the Future in Coastal and Port Approaches
Authors: Richardson R. B.
Published: January 2010

The following article is a summary of a paper presented by the author to a meeting of the Liverpool branch of the Institute on 26 January 1968.

Many people believe that there is a compelling need to discuss much more seriously than we do the whole way ahead into a new era in the conduct of ships; to scale the heights that lie above the chaos of detail and the log-jams of orthodoxy, and to discover where the truth is most likely to lie in this respect, for obsolete thinking is far more harmful to progress than obsolete equipment and this thinking, therefore, can often become a dominant factor.
Submarine Navigation
Authors: Lee T. R.
Published: January 2010

In the sixteen years since the last paper on this subject was published in the Journal (1951, 4, 288), some notable changes have taken place in the design and capabilities of submarines. Nautilus, the world's first nuclear submarine, was laid down in 1952 and completed in 1955. Since then a further 120 nuclear submarines have been commissioned. Now, a large proportion of the world's submarines are ‘true’ submersibles, self-sustaining over periods of months in everything except food; capable of proceeding submerged faster than the average surface ship; and rarely requiring to surface or even to come to periscope depth.
‘The Metrication of Navigation’
Authors: Turner R. , Sadler D. H. , Horscroft A. D. , Fifield L. W. J.
Published: January 2010

Mr. Sadler rightly emphasizes one aspect of time: that is to say time is one coordinate of a space-time set of coordinates that locate an event. The other aspect is that of time interval and it is this that the S.I. second defines. Thus if S.I. units are used the time interval between two events is measured in S.I. seconds; the orbital period of the Earth on its axis (referred to a specified frame of reference) is a certain number of S.I. seconds and, in this context, unless this happens to be 86,400 it is surely incorrect to call this interval a day.

Charles Cotter says my note is controversial. I do not think this is so. The controversy lay in the decision to adopt S.I. units. My purpose was to indicate the implications of this decision. The S.I. unit of plane angle is the radian and hence the argument for the retention of a unit of distance related to the minute of arc is not relevant. The problem involved in adapting rhumb-line sailing to S.I. units is not difficult and has already been dealt with with great clarity. The advantages of a single universal coherent system cannot be over-emphasized and it is to be hoped that difficulties will not be prolonged by isolated areas of resistance.
The Improvement of Navigation Lights and Signals
Authors: Lindsay Douglas J.
Published: January 2010

The Forum comments about small craft lights by Bernard Hayman clearly shows up a shortcoming in the original argument put forward. In relegating the single white light to small craft, and then forgetting it, I have failed to develop this particular argument to its conclusion.

Although I cannot agree with Mr. Hayman's reasoning, the shortcoming must be rectified. To this end, may I propose that: ‘Vessels of less than 65 ft., propelled by any means (sailing vessels by definition are excluded from this), to show a single white light, visible all round the horizon for a distance of at least 5 miles. This light to be not less than 9 ft. above the gunwale. These vessels also to show sidelights prescribed in Rule 7(a(ii)), or if less than 40 ft. in length, may show in lieu the lantern prescribed in Rule 7(d).’
Guidance and Control Philosophy for All-weather Landing
Authors: Jones S. S. D.
Published: January 2010

This paper, which was presented at an Institute meeting held in London on 21 January 1970, suggests a range of philosophical implications which result from the interaction of guidance and control systems in the context of all-weather landing of fixed-wing aircraft. It then attempts to deduce the considerations which must be applied to the approach to the engineering solution to the guidance and control problem.

In the context of this paper the terms guidance and control have specialized connotations which have achieved the status of common usage.

As they are used in the all-weather operations (AWO) jargon they are easier to define as adjectives than as nouns; the ‘guidance system’ is the system which defines the flight-path which the landing aircraft must follow and the ‘control system’ is that part of the aircraft equipment which enables the aircraft to follow the flight-path which has been defined by the guidance system.
A Two-Component Electromagnetic Ship's Log
Authors: Tucker M. J. , Smith N. D. , Pierce F. E. , Collins E. P.
Published: January 2010

A ship's log is described which works on the principle of electromagnetic induction. The measuring head contains a coil with a vertical axis and is arranged so that voltages are picked up proportional to the two components of water flow past it. The electronic circuits are designed to give a true and stable zero by using a low-frequency squarewave energizing current. Laboratory tests show the output to be linearly related to water velocity. Because of the complicated flow patterns round a ship, the log must be calibratedin situat sea. Calibration of the forward component meter follows the usual procedure and this meter is accurate to about ±0·1 knot or ± 1 per cent, whichever is greater. However, calibration of the athwartship component meter is difficult and time-consuming, and the sensitivity is dependent on forward speed. With care, it seems that an accuracy of ±0·2 knot or ± 10 per cent, whichever is greater, should be possible with this meter, but more experience of such calibrations is required. The paper is discussed on p. 319.
Operational Research and Cost Benefit Analysis on Navigation with Particular Reference to Marine Accidents
Authors: Stratton A. , Silver W. E.
Published: January 2010

The objective of navigation is to ensure safe and economic operation of the craft and new trends and developments in navigation have to be judged against the return that they might be expected to bring in operating economics and reduction in accidents. Modern technology offers a wide range of fascinating possibilities, many of which will be discussed at this quadripartite meeting. The potential of these new trends and developments, however, cannot be judged just on the basis of the improvement they bring to the reckoning of position and course. This is but the starting point (Fig. 1) to a complex interaction between navigation, operator and the world at large. The operational navigation performance is determined by the interaction between the means of reckoning position and course, the operational situation and the human operator's interpretation of the operational situation in relation to such regulations, rules and procedures as have been established.
A Three-dimensional Simulator for Manœuvring of Surface Ships
Authors: van Manen J. D. , Hooft J. P.
Published: January 2010

The rapidly growing demand for more information on the manœuvrability of ships is distinctly recognizable nowadays, especially by an industrial service institute in the field of ships’ hydrodynamics like the Netherlands Ship Model Basin. At this moment, means like manœuvring basins, rotating arms and towing banks with planar motion systems are available at many places. The information obtained from ship-model tests in such facilities is still insufficient to satisfy all questions. There is a growing interest in training people under the circumstances which will confront them on ships in the near future. Governments, harbour authorities and shipowners like to know the criteria by which a decision to enter a harbour with a large ship can be taken. The human aspects of manœuvring very large ships have raised an interest in designing semi-automatic pilots. A clear explanation of the role of the human operator was presented by Segel at the ‘First Symposium on Ship Manoeuvrability’ in Washington in 1960. That paper discusses the many items that influence the path of the ship, which the pilot, captain or helmsman desires to follow. The block diagram presented in Fig. 1 illustrates the complexity of the phenomenon.
The New Reach in Navigation at Sea
Authors: Richardson R. B.
Published: January 2010

When we look at the sea today we find a new world being unfolded. We find oceanology, the art of living on and using the sea-bed, no longer the sole domain of Jules Verne. Whole areas are devoted to the production of oil and gas from the seabed, with their rigs bringing literally new horizons as well as new hazards. Whole areas of the sea required for mankind's subsistence will be set aside in the eyes of civilization for purposes other than navigation. The sea will no longer be sacrosanct to ships and seamen alone.
The Cumulative Turn
Authors: Bell Frank Coffman
Published: January 2010

Captain F. J. Wylie is, of course, the complete master of the cumulative turn in all its aspects, not for a moment omitting the mathematical. And Commandant L. Oudet has greatly contributed to the study of this important and interesting subject in collision theory. He has provided detailed and lucid information on actual cases, brilliantly researched and reconstructed in a manner that would do credit even to the immortal analyst the Chevalier C. Auguste Dupin. There is indeed little that can be added to what these two and other distinguished authors have already recorded in the pages of thisJournal, most notably in Wylie's 1963 article, Collision at Sea in Fog: The Commonsense Approach (16, 100), Oudet's 1965 article, Collision and the Courts (18, 188), and Wylie's article, Legal Aspects of Radar and Collision (18, 203). It also turns out that Wing Commander E. W. Anderson has made a most important contribution to this subject.
An Examination of some Ship Radars with Automatic Computation
Authors: Wylie F. J.
Published: January 2010

It is generally accepted nowadays that, to obtain full value for anti-collision purposes from the use of radar by a ship proceeding in poor visibility, it is necessary to plot, or to compute in some other way, the raw data which may be obtained from the radar. It is also usually conceded that, for this to be done effectively in frequented areas, without the aid of mechano/electronic devices, a great deal of time and expertise is demanded from the radar observer and a great deal of responsibility thereby rests upon his shoulders.

To reduce the load of work and the possibility of human error and to give the observer more time to use his intelligence in appraising the situation and keeping it under review, radar engineers are already pressing forward the development of automatic devices which, in one way or another, produce computed informatioa in the form ultimately needed.
Simplified Tidal Calculations
Authors: Black A. N.
Published: January 2010

The Admiralty Tide Tables give the utmost accuracy in tidal calculations, but at the cost of a number of tedious interpolations. Many seamen, particularly those in small vessels, would be willing to sacrifice some of this accuracy if they could have a simpler form of calculation. In any case meteorological effects, and the uncertainty of the time and height corrections for some of die smaller ports impose uncertainties which upset the apparent accuracy. In fact many yachtsmen do not use the Admiralty Tide Tables, but use tables in commercial almanacs, usually giving the times and heights of high water only.
Revised Rules for Preventing Collisions at Sea
Authors: García-Frías J.
Published: January 2010

Captain P. A. Thompson's paper, Revised Rules for Preventing Collisions at Sea, in the January issue of theJournalshould be discussed. I agree with him that ‘rules (the ones which are mainly based on the operational aspect of the collision problem, i.e. manœuvring rules) to cover every conceivable circumstance would be of such length as to be impracticable.’ However, in my opinion, rules based on the principles—the organic aspects—can cope practically because then the object of the rules is to define the collision problem and its solution so that use of the rules can be immediate, easy and effective. For example, by establishing a safety distance the passing operation would have to be carried out such that the miss distance would always be greater than the safety distance. Furthermore, by keeping the ship's range above the safety distance, one ensures that the entire operation is correctly carried out.
Metrication and the Nautical Mile
Authors: Turner R.
Published: January 2010

This country, and the marine industry in particular, is in the throes of a change that it has been decided shall be called metrication. It is evident from what is both written and spoken that not everyone is aware of what metrication means, that many people assume that it is simply a change from imperial units to metric units. However, what is really intended is the adoption of the S.I. system of units and this implies much more than just the use of metric dimensions. The two main points of the S.I. system are (i) that every dimension is measured in decimal multiples of a basic unit and (ii) that the system of units is a coherent one. The educational advantages of such a system are too well known to require restating here. Antagonists of change usually point out that time does not conform to condition (i) and while this is true, nevertheless the S.I. system will be a great improvement on our present one and the non-conformity of time should not be used as an excuse for other non-conformities.
Radar Usage and Speed in Fog
Authors: Robb E. M.
Published: January 2010

The use of radar in relation to the Rule of the Road at sea is a subject over which there is still a great deal of controversy. An examination of the main problems involved was made in this Journal (Vol. 3, No. 1, January 1950) by Captain F. J. Wylie who concluded in his paper that the use of radar might justify a more liberal interpretation of the term ‘moderate speed’ than has hitherto been countenanced; and a recent amendment to theKing's Regulations and Admiralty Instructionsclearly accepts the use of radar as an existing circumstance within the meaning of Article 16.

No attempt, however, has so far been made to arrive at a precise definition of ‘moderate speed’, and it may well be that the reasons which prevented a definition being made in the non-radar case are in fact given more force when radar, with its added variables, is used. On the other hand it is unlikely that any progress in the matter can be made without a full discussion of the factors involved, and Captain Robb's paper, though it may be possible to dispute some of his conclusions, is presented here as an interesting attempt to achieve a definition which can serve as a guide to shipmasters.—Ed.
Light Aircraft Navigation
Authors: Townsend Michael
Published: January 2010

This paper is an appreciation of the navigational problems encountered during a flight round the world in 1948, in a single-engined light aircraft. The route chosen (Fig. 2) covered nearly every type of flying weather in the world, from the perfect conditions of the Mediterranean in the summer to the severe climate of the Aleutian islands; navigation tests were provided by the overwater flights across the South China Sea (Hong Kong—Okinawa = 900 miles), the North Pacific (Chitose—Shemya = 1730 miles) and the North Atlantic.
Optimum Flight Paths
Authors: Fraser D. O.
Published: January 2010

A condensed version of a paper presented to the Centre Beige de Navigation, Brussels, 9 January 1950.

The fact that the most expeditious route between two points on the Earth's surface is not necessarily a great circle is no new discovery. In the days of sailing ships courses were set to take maximum advantage of the wind; the trade winds were so called because they made the voyages of the trading ships possible. To a large extent they dictated the sea lanes and it was not until the arrival of the steamship that more direct routes across the oceans could be followed.
L. J. Comrie's Contribution to Navigation
Authors: D. H. S.  , P. F. E.
Published: January 2010

Members will have learned with regret of the death of Dr. L. J. Comrie, M.A., PH.D., F.R.S., who died at the age of 57 on 11 December 1950. Dr. Comrie's contributions to science were primarily in the fields of astronomy and computation, and in the latter field he may be said to have created the modern concept of scientific computing and to have laid the foundations for the present widespread interest in numerical methods and in digital calculating machines. Tributes to this side of his work have already been paid, both here and abroad, and the Royal Society and the Royal Astronomical Society are both publishing fuller notices which will give a detailed assessment of his work. The following note, pays a tribute to Dr. Comrie's contribution to navigation.
Winter Navigation through the Strait of Belle Isle
Authors: Simmons R. E. G.
Published: January 2010

The shortest route from the Great Lakes and St. Lawrence River to Europe passes through the Strait of Belle Isle. The alternative routes pass through the Cabot Strait and are between 100 and 400 miles longer according to the European port of destination. The Strait of Belle Isle is, however, normally closed to navigation from the end of December until the middle of July due to the presence of pack ice and icebergs.

Air reconnaissance patrols flown over the Labrador, Belle Isle and East Newfoundland areas seem to indicate that, for the past few years at least, ice conditions have not been so severe as to hamper navigation throughout the normal period of closure. Consolidated ice is only present from the third week of January to mid-February and clears in mid-April to mid-May; only icebergs present a problem in May and June. It is hoped t o show that with proper air reconnaisance at the beginning and end of the ice season, navigation through the Strait could be extended to eight or nine months of the year, or even longer, instead of the present short season of only 5½ months.
Routing in the North Sea
Authors: Sohnke F.
Published: January 2010

The structural changes in shipping since the war and the trend towards super-tankers, large bulk carriers and fast freighters is unmistakable. Fast ships are expensive and it is natural that the large investment in these ships should be balanced by increasing the number of voyages and reducing the time spent in port. In this connection radar provides a welcome aid towards faster voyages, for even in foggy weather ships equipped with radar can reach their destinations earlier.
The Bordeaux Port Radar
Authors: Girardin A.
Published: January 2010

At the end of 1963, to assist ships making use of the extensive facilities in the Gironde estuary, the port of Bordeaux installed surveillance radar covering the mouth of the Gironde. As it is still too early to assess its potentialities, this paper describes the technical arrangements and makes some general comments on the use of radar, suggested by the new installation.

Ships approaching the Gironde estuary from the open sea follow the buoyed channel from the landfall buoy BXA, 18 kilometres west of Pointe de la Coubre. After picking up the pilot they enter the western or outer entrance passage, whose seaward termination lies 8 kilometres from the coast. This provides a dredged channel, 800 metres wide and 3500 metres long, running east–west. The depth of 12 metres at low water springs enables ships to cross the annular river bar separating the deep water on the seaward side from the mud banks at the mouth of the inner channel.
Human Factors in Bridge and Chartroom Design
Authors: Walraven P. L. , Lazet A.
Published: January 2010

When designing a bridge for a naval vessel the designer faces a number of requirements which are quite different from those of a merchant vessel. Besnard states that besides a good view, the officer of the watch requires by him the instruments for determining direction and distance or speed, position finding instruments and other electronic aids, and the means of communicating with the helmsman and engine room as well as some check on these communications. He concludes that a cockpit arrangement of the instruments would suit the requirements. Rees, on the other hand, doubts whether the officer of the watch would remain alert for long periods when sitting in an enclosed compartment, and suggests that a cockpit arrangement is only appropriate where there is little space. Further he argues that the duties of the officer of the watch extend beyond those of simply directing the ship.
The Minimum Navigational Equipment for Supersonic Transport
Authors: Hardouin J.
Published: January 2010

The navigational problems presented by supersonic aircraft do not differ essentially from those with modern four-jet aircraft. Navigation will still entail three main tasks:

i. To ensure that the crew knows the position of the aircraft at any given moment, within a reasonable time, and with the necessary accuracy.

ii. To ensure that the aircraft is operated under the best conditions of route, speed and height for profitable operation.

iii. To ensure compliance with air traffic control.
The Presentation of High Ground Information
Authors: Freer T.
Published: January 2010

Information on the shape of the ground can be required in the air for two quite different reasons. First, for visual fixing of position, that is to say, for ‘map-reading’; and second, for ensuring terrain clearance when flying on instruments. Obviously the second is of far greater importance than the first, yet unfortunately it is the first that, for historical reasons, has received the greater attention from cartographers; this paper will try to redress the balance, and indicate where action is needed at the present time to satisfy the second requirement.
The Initial Descent Problem
Authors: Smith H. E.
Published: January 2010

T‘HAT there is a general problem in avoiding high ground has been demonstrated somewhat catastrophically in recent years, but this paper deals with the descent phase of flight in a jet operation, where most of the incidents and accidents to scheduled international services have occurred. My own examination of these incidents and accidents (in some cases somewhat cursory) has led to the conclusion that in stating the problem in terms of ‘the avoidance of high ground’ there is the danger that we will miss the primary problem and indeed mislead the experts who might have little difficulty in providing us all with airborne radar designed for this particular purpose.
A Note on the Kamal
Authors: Taylor E. G. R.
Published: January 2010

An important nautical manuscript in the Bibliothéque Nationale, Paris, containing a number of separate sections on Portuguese navigation methods, and written in the early sixteenth century, has been translated into modern Portuguese and edited by Professor Albuquerque of Coimbra. It is the Livro de Marinharia of André Pires, a Portuguese pilot only known by this collection, of a small part of which he was the actual author. The 13th section, which is quite short, deals with the ‘Balestilha of the Moors’, i.e. the kamal. The use of this title confirms the point, for which there is some other evidence, that although the quadrant and the (sea) astrolabe were the official navigating instruments on Portuguese ships, the cross-staff or balestilha was known and used. The principle of the kamal was, of course, that of the cross-staff. A wooden rectangular tablet was held up with one edge on the horizon, the other on the heavenly body. A knotted cord running from the centre of the tablet was held taut between the observer's teeth, and all he had to know was the meaning of the knot in his mouth in terms of ports and landmarks. The first knot—nearest the tablet—measured the ‘altura’ of Mascat, which was east-west with Diulcende, on the coast of Diul in India. The fifth knot marked the altura of the Curia Muria Is., east—west with Dabul, and so on.
Radar Practice in Fairly Dense Traffic
Authors: Clissold P.
Published: January 2010

There are occasions when, because of the density of shipping and/or lack of sea room, ships navigating by radar in thick weather cannot avoid passing within a distance of two miles, the least distance usually considered desirable. In such a situation a simple plan of procedure and of avoiding action, if possible to devise, should greatly reduce strain on the navigator and so increase the safety of navigation generally. Also, if such a plan came to be generally followed, safety would be further enhanced, because each navigator would know what the others were likely to do.
Optimum Ship Routing
Authors: Hanssen George L. , James Richard W.
Published: January 2010

The paper describes the system developed and used by the United States Hydrographic Office for selecting the optimum track for transoceanic crossings by applying long-range predictions of wind, waves and currents to a knowledge of how the routed vessel reacts to these variables. Over a period of two years, over 1000 optimum ship routes were provided to one authority, with an average reduction in travel time of 14 hours.
Anti-collision Radar Sectors
Authors: Garcia-Frias J.
Published: January 2010

Both the argument and the geometry in this paper require careful study before they can be appreciated; it is hoped that the following notes, which are restricted to purely geometrical considerations, will assist readers to understand them.

The author's fundamental argument is that it is geometrically impossible for ships A and B, at distance r apart and moving with constant speeds v and u, to approach each other more closely than distance d (less than r) if the courses of ships A and B are each restricted to a semi-circular anti-collision sector, depending only on the angle δ sin δ = d/r, and on an agreed universal convention. This is illustrated in Fig. 1 in which the two sectors are indicated by vv' for ship A and uu' for ship B. Adopting the convention that the ships pass ‘port to port’, the permissive anti-collision sector for each ship is, relative to the bearing of the other ship, from δ to starboard, increasing to 180° and to port from 180° to 180° −δ . This is equivalent to restricting the course so that the other ship bears more than δ to port or more than 180°−δ to starboard.
‘Manœuvres to Ensure the Avoidance of Collision’
Authors: Sadler D. H. , Harries H. D. , Clissold P. C. H. , Freiesleben H.C.
Published: January 2010

The following comments have been received on Mr. E. S. Calvert's paper, published in the last number of the Journal. A further selection of comment, including a note by Captain F. J. Wylie, and possibly a reply by Mr. Calvert, will be published in the next number.
A Miniature Stabilized Platform
Authors: McClymont T.
Published: January 2010

The platform shown in Fig. I is one of a series of miniature platforms developed for inertial guidance and weighs only 28 lb. It is a three-axis, four-gimbal platform permitting complete freedom of manœuvre without gimbal lock. Three miniature integrating gyroscopes are used for stabilizing the gimbal system (Fig. 2) and three miniature pendulous accelerometers provide voltage outputs proportional to accelerations experienced by the platform.
Matthew Flinders, Hydrographer
Authors: Ritchie G. S.
Published: January 2010

In the bicentenary year of the birth of Matthew Flinders at Donington, near Boston in Lincolnshire, it is my privilege to present to Members of three notable British societies some details of the life and work of this great hydrographer.

His surveying and charting impact was made entirely in Australian waters and he is probably better remembered in that country today than he is in his homeland. It is my hope that my discourse, added to the many activities that have been arranged in Britain this year, will do something to rectify this situation. My talk will attempt to tell the brief story of Flinders' 40 years of life and work, beset in his later years by many misfortunes. I will also examine in some detail how Flinders conducted his surveys by taking a few isolated examples, and finally briefly review the results of his labours.
Systems Engineering Aspects of the Proposed Channel Navigation Information Service
Authors: Griffiths P. F. C. , Jarman D. R.
Published: January 2010

This paper, by the head and the deputy head of the Civil Marine Navigational Aids Division of the Admiralty Surface Weapons Establishment, deals with certain problems relating to the proposed Channel Navigation Information Service, including radar coverage, the transmission of information, computer assistance and information display. The paper was read at a meeting of the Institute held in London on 30 January 1974 with the President in the Chair.

Much of the background to marine traffic problems in the Dover Strait has already been discussed in previous issues of this Journal. It was decided in 1971 that some radar surveillance of the area would be appropriate. The first steps were taken when a radar trial was conducted by A.S.W.E. in the St. Margaret's Bay area near Dover in 1971. As a result of these trials the Coastguard station at St. Margaret's was fitted with a standard marine radar as an interim solution.
The Quantitative Description of a Traffic Control Process
Authors: Ratcliffe S. , Gent H.
Published: January 2010

A practical traffic control system can be envisaged as a hierarchy of control loops, each serving to convert a traffic demand into a potential traffic flow. Each loop is concerned with problems that can be foreseen to arise at some time in the future and the distinctive characteristic of any loop is the distance ahead, in time, to which it prognosticates. Although this model is probably applicable to most traffic systems the present note will apply it in the context of air traffic control.

Figure 1 shows a whole family of possible control loops. (Not all of these are present in all A.T.C. systems.) In each loop there is a mechanism for the prediction of future traffic. This prediction is compared with certain internal criteria and, if these are not satisfied, some control action is taken to coerce the traffic pattern into some more acceptable form. It is characteristic of most of these loops that they cannot be proved to be capable of safely handling all conceivable traffic demands; there is an implicit assumption that the superior elements of the control system will not tolerate a traffic demand which is beyond the handling capability of the inferior loops, but that a residue of unsolved problems can generally be left to be handled further down the chain.
I.—The Impact of Digital Computing
Authors: Grindon-Ekins P. M.
Published: January 2010

Airborne computing has been with us since the very early days of aviation when it comprised such basic calculations as TAS from the observed parameters of IAS, temperature and altitude. The display requirement for this type of computing was virtually negligible. However it was appreciated that where instruments could take over the repetitive processes of navigation the aviator could devote his time to tasks which he could perform better than the machine, calculations which he could perform more speedily or more economically than the technology of the time made possible and those which required the intuitive reasoning which has always made navigation a combination of art and science. The Air Position Indicator is an example, and its logical extension the Ground Position Indicator. These analogue computers not only freed the navigator from a great deal of repetitive work but provided a consistent accuracy, and some limited tactical flexibility. The demand for display was still small and easily accommodated in the relatively uncluttered crew positions in early aircraft. As aircraft systems became more complex and speeds increased, the increased workload meant that the crew were not capable of accepting all the information from the increasing number of sensor displays and calculating position, heading to fly, E.T.A., fuel state, and so on, with sufficient rapidity for the required accuracy to be maintained. With the aircraft coming into service it was also necessary to consider optimum altitude and minimum-fuel flight paths.
The Manœuvrability of Ships as Influenced by Environment and Human Behaviour
Authors: Hooft J. P.
Published: January 2010

This paper by the Vice-President of the Netherlands Ship Model Basin presents the results of a study performed on the N.S.M.B. ship manœuvring simulator aimed at the development of criteria for the manœuvrability of ships sailing in a current. Six pilots navigated four types of 250,000 d.w.t. tankers in sixteen different conditions of current.

Ships have grown so large that it is no longer taken for granted that they can be manoeuvred as required. The problem can be split up in two aspects, the ship's inherent manoeuvring ability, which is mainly a technical problem, and the mariner's ability to manœuvre the ship, which is mainly a psychological problem.
A Study of a Species of Short-Method Table
Authors: Cotter Charles H.
Published: January 2010

This paper discusses navigation tables based on the decomposition of the astronomical triangle into two right-angled spherical triangles by a great circle arc extending from the zenith to the meridian of an observed celestial body. In a recent fairly comprehensive study of some thirty short-method tables in which the division of the PZX-triangle forms the principle of construction, nineteen are of the species to be discussed.

Following the introduction in 1871 of the first short-method table by Thomson, some twenty years were to pass before any real advance was made in this field. Thomson's table was in fact re-issued by Kortazzi in 1880 and by Collet in 1891, in modified forms, but it was Professor F. Souillagouët of France who is to be credited for introducing something novel and decidedly better than Thomson's table. Unlike the earlier ones it was designed specifically for the Marcq Saint Hilaire method of sight reduction and, in contrast to Thomson's table which was based on the division of the PZX-triangle by a perpendicular from X, Souillagouët's was based on division by a perpendicular from Z.
The Use of Astro-navigation in Fast Aircraft
Authors: Jessell A. H.
Published: January 2010

Astro-navigation cannot be regarded at present as one of the principal aids to air navigation. It suffers, by comparison with radio aids, in that it is slow in use and much more subject to interruption by bad weather. The average navigator needs at least 15 minutes to take and plot a two-star fix with present methods. This is quite a long time in the air, though not prohibitive with present-day aircraft, and in consequence astro-navigation is now used extensively only on long flights over sea or desert where radio aids are lacking.