bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Altimeter Display
Authors: Melchior F. G.
Published: January 2010

Before commencing an analysis of the subject matter at hand, it will be as well to present some definitions which we have adopted, in our own work, even if they represent in part arbitrary interpretations of our own.

(a) Pressure altitude is, of course, nothing but barometer pressure at any given elevation, converted into equivalent altitude (feet) units; hence a variable.

(b) Sea-level in connection with altimetry is only a theoretical reference value which does not necessarily conform with mean-high water; in terms of pressure altitude, needless to say, it is also a variable.

(c) True altitude (above sea-level) cannot be obtained with satisfactory accuracy by merely correcting for sea-level barometer pressure. On the other hand, we must dispel the notion—not uncommon—that one can obtain more accurate altitude values by correcting for temperature and humidity at a particular flight level. There are such things as inversions and convection currents; we do not need cold weather to have a high barometer, and sometimes it is warmer a few thousand feet up than at ground-level.

(d) Performance of pressure instruments is properly expressed in parts of the pressure range—not in per cent of altitude—and the reason is simple: at, say, 60,000 ft. you have about 16 times as may feet per unit of pressure as at sea-level.

(e) Sensitivity is—technically speaking—the smallest part of the pressure range that will produce a measurable response.
Prediction of Wave Characteristics Over the North Atlantic
Authors: Darbyshire J.
Published: January 2010

This paper develops a method for the prediction of wave height, period and direction on a 200-mile grid over the North Atlantic Ocean, using a wave spectrum technique. The method could be useful in conjunction with optimum ship routing across the ocean.

AS discussed recently by Hanssen and James, ship routing across the ocean, using the optimum route with respect to weather conditions, is now becoming a practical possibility. One essential requirement is to predict the wave heights and lengths over all parts of the area concerned. This would require first, of course, a forecast of the wind conditions. At present the Meteorological Office issues prognostic weather charts 24 hours ahead and wave predictions must be tied to them. Wave conditions are not determined instantaneously by the weather conditions at a given time, but tend to be an integration of the weather conditions over two, three, or even more days before and so wave predictions 24 hours ahead are likely to be more accurate than the wind forecasts.
The Polaroid Procedure for Photographing Radar Screens
Authors: Klerk J. A. , Steensma W.
Published: January 2010

When reading articles on radar-navigation in various nautical magazines, one is constantly struck by the difficulty of comparing the different targets on the screen and of interpreting the changes that take place in the right way. So plotting becomes still more necessary in order to get: (a) the nearest approach, and (b) the present course and speed of other vessels, before we can manœuvre to avoid collision, especially in thick weather. When plotting, comparisons are hampered by the fact that the echoes must be recorded on a piece of paper or on the reflection-plotter, and that the different distances, courses and speeds must be measured very accurately. And nearly all these tasks depend upon the skill and accuracy of one man.
I.—Training for Safe and Efficient Ship Operations
Authors: Holder L. A.
Published: January 2010

Looking at the practical training for operators of future ships we are confronted with a wide range of sub-systems which may at some future date be grouped in a central ‘operations control’ point. The array shown in Fig. I is by no means exhaustive. The selection, education and training of personnel for the conduct of international shipping is of world importance and the United Kingdom has a wealth of experience which is respected by other maritime and would-be maritime nations. In this paper it is only possible to take a narrow and rather short-term view of requirements within the present manning and training structure.
III.—Training Methods for Navigation in the Air
Authors: Robinson W. P.
Published: January 2010

The civil aviation problems in training navigators may appear simple compared with those of our marine colleagues, and possibly also in comparison to the military side of aviation. In civil aviation we are concerned with tactical problems but not to the same extent as in marine and military aviation, but there are those amongst us who can recall the halycon days of flying boats when we too were concerned with the tides and the state of the water. Since the end of the war there have been far reaching changes in civil aviation and navigation. The object used to be one of getting from A to B and battling a great deal with the unknown—long night hauls across the North Atlantic, Shannon and Keflavik, icy cold arrivals at Goose and Gander, pressure pattern flying and so on, with the minimum of navigation equipment, poor weather forecasting and limited range aircraft. Nowadays civil aircraft range is not the problem it used to be, although some such problems still exist, navigation equipment is more sophisticated and the A.T.C. requirements much more stringent. It is not so much getting from A to B as staying as close as possible to an assigned A.T.C. track.
IV.—The B.O.A.C. Navigation Procedures Trainer
Authors: Burt J. C.
Published: January 2010

The heart of the B.O.A.C. Navigation Procedures Trainer (NPT) is a general purpose digital computer (Elliotts 905) and the programs have been contained within a memory store of only 16,000 words. There are fourteen cubicles for the pupil navigators and one for the instructor. At each cubicle is the usual chart table and stowage for manuals; navigation information appears on a CRT screen in the form of letters and numbers. Requests for radio bearings, astro sights and so on are conveyed to the computer by means of a typewriter keyboard and some simple codes which are shown on a plaque to the left of the CRT. Only a few of the keys are special ones.
V.—The R.A.F. Air Navigation Simulator
Authors: Robertshaw K. , Tiffen J. A.
Published: January 2010

No. 6 Flying Training School at R.A.F. Finningley trains all R.A.F. ab initio navigators as well as refreshing the failing memories of its ageing qualified navigators, tasks which have been helped over the last 18 months by the introduction of an air navigation simulator based on a digital computer. The simulator can seat 15 students in three banks of 5, each bank being controlled by an instructor seated at a control console. The diagram on p. 267 shows the layout of one self-contained bank of 5 cubicles. In front of each console is a track display unit (TDU) on which the briefed route is traced drawn in ink on a ground glass screen. The students’ cubicles are instrumented to simulate the Dominie advanced navigation trainer but there are additional facilities so that Varsity sorties may be flown by students in their basic phase of training.
A Quantitative Analysis of Avoiding Action
Authors: Hasegawa K. , Kasahara K. , Yamazaki Y. , Kai Y.
Published: January 2010

There have recently been various investigations of avoiding action when a ship is navigating by radar. The present paper attempts a numerical analysis of the changes in the apparent motion of the echo of the other vessel on the radarscope when both vessels alter course and speed simultaneously.

First we consider the case where the echo of the other vessel is approaching the centre of the radarscope—that is the vessels are on a collision course.

In Fig. I AOB represents a velocity triangle:

OA = own vessel's course and speed

OB = other vessel's course and speed

AB = other vessel's relative course and speed

When both vessels alter course, by Δα1 and Δα2 respectively, the velocity triangle becomes A′OB′ and A′B′ represents the new relative motion of the other vessel. If the triangle A′OB′ is rotated through Δα2 about O, and OB′ coincides with OB, the triangle is represented by BOC and < CDA′ = Δα2. The change θ in the other vessel's relative course caused by both vessels altering course by Δα1 and Δα2 respectively is therefore:

Now φ can be shown to satisfy the equation:
Situation Display
Authors: Prior P. O.
Published: January 2010

This paper was presented at a meeting of the Institute held in London on 12 January 1973 with the President, G. E. Beck, in the Chair. Mr. Prior, Director and General Manager of Kelvin Hughes, discusses factors influencing the commercial development of an innovation in navigational equipment and the inevitable time lag in production for the market. A technical description of Situation Display, the new marine radar system from Kelvin Hughes, was published in the April issue of this Journal. The discussion printed here relates both to Mr. Prior's paper and the technical description.
Strapped Down Inertial Navigation Systems
Authors: Collinson R. P. G.
Published: January 2010

The heart of an inertial navigation system is the Inertial Measuring Unit (I.M.U.) as this carries out the fundamental tasks of measuring the vehicle acceleration and providing a spatial reference. The I.M.U. thus determines the system performance and accuracy; it also accounts for about two thirds of the initial cost of the system and is a major factor in the cost of ownership.

Up to now the majority of IN systems have used a stable platform I.M.U. where the gyros and accelerometers are mounted on a gimbal suspended platform which is servo controlled from the gyros. This has greatly eased the task of developing suitable gyros of the required accuracy, as the gimbal stabilization system isolates the gyros from the angular motion of the vehicle and greatly simplifies the subsequent computation in terms of axis transformations; it provides a direct read out of the euler angles—heading, pitch and roll. However such a system is inevitably mechanically complex and its ultimate reliability is constrained by such components as slip rings, servo motors, synchros, resolvers, encoders, gimbal bearings &c.
The Use of a Computer for Correcting Ocean Soundings
Authors: Sherwood Ruth
Published: January 2010

The velocity of sound in water is a function of temperature, salinity and pressure. When an echo-sounder is used to make depth measurements, the time taken for a pulse to reach the ocean bed and return is measured. The machine is set to a standard sounding velocity, usually 800 or 820 fm/second (1463/1500 m/sec), and a nominal depth is recorded. This depth should then be corrected for the properties of the water. The ‘Tables of Velocity of Sound in Pure Water and Sea Water” by Matthews are commonly used for this purpose. Matthews compiled his tables using soundings taken by a number of research ships all over the world. He divided the oceans into 52 areas, and for each area calculated a set of depth corrections from 200 m to the ocean bottom. Since the tables were published more accurate measurements of velocity as a function of temperature, salinity and pressure have been made. There are also many more observations than were available when the tables were compiled. However, as these tables are in general use, no attempt has been made in this paper to change the corrections, and any computer results are therefore no more accurate than the tables.

When correcting depths manually aboard ship, the following procedure is followed. The depth on the echo-sounder is noted and entered into a log book. The position of the ship is known using some standard method of navigation such as satellite, Decca, Loran or radar.
A Visit to Japan
Authors: M.W.R
Published: January 2010

At the invitation of the Nautical Society of Japan, a society with aims similar to the Institute's, the Executive Secretary visited Japan between 5 and 17 April. A short report to Council follows.
Four-Point Mooring
Authors: Lees K. G.
Published: January 2010

H.M.S. Reclaim was built in 1948 by Simons & Co. of Renfrew as a salvage ship of the King Salvor class but altered before completion for her role as a deep diving vessel. She established world deep diving records in 1948 (536 ft., 163 m.) in Loch Fyne, the diver wearing a standard diving dress and breathing a mixture of oxygen and helium, and in 1956 (600 ft., 183 m.) off Norway. In 1964 she carried out a series of dives to 600 ft. for one hour, off Toulon, the divers wearing lightweight self-contained equipment. In 1950 she located the sunk submarine Truculent in the Thames estuary and in 1964 the submarine Affray, when underwater television was used for the first time. In 1966 she recovered a crashed Viscount aircraft in the Irish Sea. Reclaim is now engaged in trials which will eventually permit diving for prolonged periods to 1000 ft., and therefore anywhere on the Continental Shelf.

Two divers are lowered to the sea-bed in a submersible compression chamber equipped with underwater lighting and television and in telephonic communication with the ship. While one diver swims out of the chamber to undertake the required task the other acts as attendant. The chamber when hoisted aboard under pressure is locked on to another chamber in the ship's hold, where the divers carry out the process of decompression which may take several hours.

H.M.S. Reclaim encounters some unique navigation and seamanship problems when engaged in deep diving.
The Reverse Stopping Ability of Supertankers
Authors: Tani H.
Published: January 2010

The question of the reverse stopping ability of a ship is well known but is yet a fresh problem. Until about twenty years ago the distance required to stop a.ship from a service sea speed ahead by using her engines full astern with helm midships was comparable to her advance while stopping with helm hard-over. However, at present this head reach of a 100,000- d.w. supertanker may range from 10 L to 15 L while her advance with maximum helm angle might only be from 5 L to 7 L. At first sight this appears to be a surprising phenomenon, but it is little wonder since the mass of the ship and hence the inertia increases with the cube of her length, while the total resistance of her underwater hull only with the square of her length.

The question of stopping very large supertankers is one of some significance both from the viewpoint of preparing to pick up a pilot, anchoring, berthing, or similar everyday operations and of avoiding collision or grounding in an emergency.
Handling Large Vessels in the Port of Hirohata
Authors: Onishi T.
Published: January 2010

Professor Tani's paper (p. 119) describes recent work on the problem of calculating head reach for mammoth ships of one kind and another. Handling these vessels in confined waters and bringing them alongside the berth also poses particular problems to pilots. This paper illustrates some of these problems, which of course differ to some extent for each port, by describing the pilotage procedures used in one of the new Japanese ports built to accommodate very large vessels.

1. The inland sea and large vessels. The Inland Sea has a coast line of about 4272 kilometres and covers an area of 18,000 square kilometres, equal to that of Lake Ontario. The distance from east to west is about 260 miles and the broadest part from north to south is about 30 miles wide. Navigable channels or waterways for large vessels run in all directions.
I—Decision Height and RVR Minima
Authors: Blanchard J. W.
Published: January 2010

By having a better understanding of the criteria needed for Category I operations we not only aim for an improvement in safety in Category I operations but we can move off from a more rational basis into Category II. In any case the dividing line between Category I and Category II, that is 200-ft. decision height and 800 m. RVR is not very well chosen as far as the RVR quantity is concerned and in the U.K. we generally refer to Category II as meaning a lowering of the decision height as airlines have been using lower RVR minima than 800 m. for a number of years. With the final part of the approach still having to be made visually, the main instrument approach criteria with which we are concerned are the weather minima—the critical height or decision height and the RVR or Met. visibility.
III—An Operator's View
Authors: Ormonroyd F.
Published: January 2010

It is abundantly clear that improvement in regularity and safety of operations in poor visibility can only come about through increased precision during the non-visual phase of the approach and missed approach and through continuing use of the instrument guidance to the lowest possible height within the prescribed limitations during the visual phase. In common with most other airlines, B.E.A. is planning to introduce Category II operations in the near future and this paper deals with some of the problems which we have met and the way in which we plan to tackle them.

By virtue of being an exclusively short-haul airline, B.E.A. flight times are! short compared with time spent on the ground. As a result, flight schedules need to be closely integrated to provide a high rate of utilization of both aircraft and crews, and so any serious disruption of services by the weather affects B.E.A. to a greater extent than other airlines.
‘Longitude Without Time’
Authors: Sadler D. H.
Published: January 2010

The Executive Secretary has referred to me two notes on this subject, one by M. S. Dixon and the other by Bruno Ortlepp. Although submitted independently, and at different times, they clearly relate not only to the. same technique, but also to the same set of observations.

Now much has been recently written on the determination of time, and thus of longitude, from observations of the Moon's altitude (for example, in this Journal, reference can be made to the notes by Francis Chichester, 19, 106, 1966; D. H. Sadler, 19, 107, 1966; J. J. Evans, 19, 392, 1966; and to the comments in the article by H.M. Nautical Almanac Office in 19, 133 and 1 $2, 1966) and it should be unnecessary toNrestate either the principle or the practical disadvantages of this method.
Captain Flinders
Authors: Fancourt R. St. J.
Published: January 2010

The publication of Admiral Ritchie's E. G. R. Taylor Lecture (Journal, 20, 1) brings into perspective so many names familiar to the practising navigator; indeed the achievements of these great men are surveyed and charted with great clarity. Captain Flinders receives mention only in passing and his initial surveys of the greater part of Australia do not appear on the summary diagram. Yet, in other contexts, his ship, his mentor and his kinsmen all obtain special mention.
‘The Metrication of Navigation’
Authors: Sadler D. H.
Published: January 2010

In his note (Journal 21, 81) on this subject, Ronald Turner says ‘No longer will orbital periods of the rotation of the Earth on its axis be measures of time’. This is not so, either in general or in the particular, case of navigation.

Universal Time (U.T.), which is the generally accepted name for Greenwich Mean Time (G.M.T.), continues to be essential for all purposes (in astronomy, geodesy, surveying and navigation) for which are required astronomical observations related to the precise position of the observer on the Earth's surface. The Nautical Almanac must continue to tabulate the positions of the Sun, Moon, planets and stars with G.M.T. as the time-argument; and observations should be timed in a time-system related to U.T., such as the broadcast time-signals of Coordinated Universal Time (U.T.C:).
A Hybrid System for World-wide Navigation
Authors: Stringer F. S.
Published: January 2010

In 1963, in addition to examining the characteristics of the Omega system, we were also very concerned with a comprehensive navigation system study which was designed to examine all aspects of a world-wide navigation system operating in a B.O.A.C. type environment. This concerned a study of dead reckoning as well as externally referenced sources of information. You have the choice of an all dead reckoning system probably employing multiple sensors of the same type, triple IN is typical, or you could have a mixture of externally referenced and self-contained, in other words dead reckoning sensors. Occasional reference could be made to short-range aids or even a satellite system if available to increase the integrity of the position-fixing information. The inertial and computer aspects have been examined by the Avionics Department at R.A.E. whereas the radio sensors, which are externally referenced, and the relevant software have been the responsibility of the Radio Department.
Electronic Instruments and Computers for Sailing Yachts
Authors: Gatehouse R. N. B.
Published: January 2010

This paper contains a brief survey of a series of instruments which have been developed for use in sailing yachts. It then outlines the principles of two computers; one navigational, the other for sailing performance indication. It does not cover radio navigational aids, echo sounding or radar. The data requirements are: 1. Navigational, comprising distance run through the water, heading, leeway angle. 2. Functional, comprising speed through the water, direction of the apparent wind and speed of the apparent wind.

For measuring distance run, the classical towed rotator type of log, fitted with a mechanical or electro-mechanical revolution counter has been largely superseded in racing yachts by logs employing through-hull sensors on account of drag considerations and the inconvenience of having to shorten the line when sailing slowly in shallow water. It still finds favour in cruising yachts on account of its generally lower price and its simplicity.
The Revision of the Rules
Authors: García-Frías J.
Published: January 2010

If the present Collision Regulations are defective, it is largely because the principles underlying them are not sufficiently developed for today's circumstances. In this paper Admiral García-Frías of the Spanish Navy attempts such a development and proposes a new set of rules, adapted to present circumstances, for vessels in sight of one another. These proposals, with the set of rules previously suggested in this Journal for restricted visibility using radar, form a complete system for avoiding collisions in both situations so that it would be easy to pass safely from one situation to the other when necessary, because of the unity of principles they present.

It is encouraging for certain schools of thought—which started some years ago advocating the revision of the Collision Regulations for occasions when radar was being used in restricted visibility—that there now seems to be a general dissatisfaction amongst seafarers with the lack of guidance provided in the rules. Consequently, they are at last interested in a fundamental review of the Regulations.
An Investigation into the use of Radar for Collision Avoidance
Authors: Brough J. , Jones K. D.
Published: January 2010

The introduction of marine radar into the general market immediately after the last world war, offered the promise of reducing the many economic losses sustained through failure to keep schedules during periods of reduced visibility. These promises have been only partially fulfilled. Initially it was accepted that radar needed little introduction—that it established the range and bearing of targets in the vicinity and no more was required. With radar available on only a small proportion of vessels, this limited information was sufficient to enable these few to avoid other, slower-moving craft which were not so fitted. Radar is now fitted on almost all vessels and speeds have increased, while manoeuvring characteristics have changed because of increased tonnage of vessels. The situation is now far more complex.
The Institutes of Navigation in the 1970's
Authors: Richey M. W.
Published: January 2010

This paper was presented by the Executive Secretary at the twentieth anniversary convention of the Australian Institute of Navigation held in Sydney, New South Wales, on 10 and 11 October 1969.

In July this year two men landed on the Moon, certainly the most spectacular navigational achievement of mankind. It was a voyage backed by all the massive scientific resources of a modern industrial state, in which thousands of people were directly involved. The astronauts were a single link in a navigational loop employing a host of technologies.

Two hundred years previously James Cook had sailed on the first of his three great voyages, during which he discovered New Zealand and the coast of New South Wales. Cook was perhaps the most illustrious navigator of all times, even if perhaps he advanced the art more by force of character than by any specific contribution. When he started his voyages, the art of nautical astronomy was in its infancy. At their finish William Wales could comment, in 1788, that no officer who had been concerned with them ‘would not, whatever his real skill may be, feel ashamed to have it thought that he did not know how to observe for and compute the time at sea, though but a short time before these voyages…such a thing was scarcely ever heard of among seamen; and even first-rate astronomers doubted the probability of doing it with sufficient exactness’.
Pilotage or Conning Radar
Authors: Watt J.
Published: January 2010

The paper by Captain J. P. Stewart in the July issue of the Journal, entitled as above, presents a wealth of evidence and argument for the obvious sense of designing marine radars in such a way that they can:

(a) present compass stabilized radar pictures in the natural ship's-head-up orientation. This avoids the mental stress of trying to correlate the radar view and the eye-ball view of the same situation when the two may be presented in completely different orientations;

and

(b) simultaneously allow true bearings of targets to be read off directly.
How to Avoid Collision with Other Aircraft
Authors: Proctor J. D.
Published: January 2010

These notes on collision avoidance by an experienced airline pilot are presented in the form of practical advice to young pilots. The paper deals first of all with blind avoidance and then with visual avoidance.

Collisions are rare and about one quarter of colliding aircraft have landed safely. Collisions are not always fatal to everyone, but they are serious accidents. Pilots need knowledge, skill, good habits and/or a little luck to avoid them. Collisions have occurred for years although in many cases the investigators have proved that the approach of the aircraft and the layout of the windows around the pilots were such that some of the pilots could have seen the other aircraft. Yet they still collided, so that obviously visual avoidance is not easy. In other cases especially in the circuit the aircraft approached and collided without much possibility of seeing each other; so remember there may be someone under your nose or above your tail who can't see you either. We all know how the high closing speed of fast aircraft is too high for human visual acuity to sort out the situation and prevent collision visually. But a number of collisions have occurred at low closing speeds and a number have occurred between light aircraft (e.g. two Convair 240's over U.S.A. in August 1953, and two light aircraft over Reading a few years ago).
An Accuracy Evaluation of a Civil Inertial Navigation System
Authors: Reynolds P. R. J.
Published: January 2010

This paper covers the performance of the Sperry SGN-10 Inertial Navigation System as demonstrated by the operation of dual systems installed in a standard operational configuration aboard four jet aircraft of Pan American World Airways incidental to a preoperational engineering evaluation programme conducted for the Federal Aviation Administration during the latter part of 1966. The primary object of this evaluation programme was to determine the system's capability of meeting the following requirements of the F.A.A.'s Advisory Circular covering the use of inertial navigation systems in U.S.- registered civil aircraft, namely:

(1) Maintain a position accuracy within 20 n.m. in the across-track dimension and 25 n.m. in the along-track dimension for 95 per cent of the time on flights up to and including ten hours duration.

(2) Automatically accomplish initial platform alignment in a normal manner in latitudes up to and including the highest normally used in civil aviation.

(3) Perform all its designed navigational functions in a normal manner at all latitudes, inclusive of polar and equatorial overflights.
Automation in Sea Transport
Authors: Parmiter G. V.
Published: January 2010

The word ‘Automation’ when applied to the shipping industry seems to invoke in the individual mind such matters as direct control of propulsion units, planned bridge lay-outs, cargo plan computers, engine data loggers and such other items of ships' equipment. Automation is thus limited in effect and confined entirely to the ship internally. Clearly this ensures that the ship as a unit is as economically efficient as modern techniques allow and is a reflection of the up-to-date attitude of mind of many shipowners.

On the other hand there is a very large field open to automation which concerns sea transport as a whole in respect of the actual conduct of ships at sea both individually and in relation to their effect on each other. It is in this field of sea transport operations that the author sees many longterm possibilities and this paper tries to give some lead into these, which so far seem to have received little, if any, widespread thought or discussion.
Automation Problems in Civil Transport Aircraft
Authors: McKinlay W. H.
Published: January 2010

Over the past two decades there has been a steady increase in the amount of electronic equipment carried by transport aircraft. This reflects the expenditure of a large amount of research and development effort, particularly in the automatic flight control field. Yet despite these developments complete automation has not been applied to air transport in the sense that it has been applied to some industrial processes. The attempts made to introduce partial automation have not always had complete success either operationally or economically.

The reasons for this somewhat piece-meal growth of automation in civil transport aircraft are varied. The most important seems to be that any new aircraft represents an evolutionary step forward. Much of the equipment must either be carried forward from a previous generation or based on it, for a mixture of operational and engineering reasons. Inter-fleet standardization in the interests of maintenance and the need to achieve safety by building on past experience are contributory factors.
Navigational Equipment in the Supersonic Concorde in 1970
Authors: Bouar M. Le
Published: January 2010

A great deal has already been written about the navigational problems presented by the appearance in the near future of supersonic civil aircraft; in this paper I shall try to give a quick description of the methods that will be available in the supersonic Concorde in 1970, with an account of the chief considerations that governed their choice. While there is no doubt that there is a specific navigational problem proper to supersonic aircraft, it does not present itself in as critical a form as some writers believe. When the present-day jets came into service there was not, strictly speaking, any real gap to be bridged. The conventional methods and means used in prop-driven aircraft were taken over, with whatever further adaptations were required for particular cases—such, for example, as polar navigation. In spite of the increase in speed, there was still sufficient time for the navigator to check position and heading at regular intervals.

However, the 300 per cent increase in speeds now envisaged (1300 knots = mach 2.2 for the Concorde) introduces a more formidable discontinuity in relation to the standards of today. At a speed of 22 miles a minute it becomes impossible for the navigator to work as rapidly as he must if he is to deal with the information provided by his sensors and carry out the necessary corrections.
The Shape of the Earth
Authors: King-Hele D. G.
Published: January 2010

The aim of the Duke of Edinburgh's Lectures is ‘to extend the horizons of navigational interest’. I have been able to interpret this literally, for if you extend these horizons far enough, what do you arrive at but the subject of this lecture, the shape of the Earth? It is a subject which has been revolutionized in the past five years by analysis of the orbits of artificial satellites: the two years from 1958 to 1960 saw more progress than the previous 200 years, and since 1960 the pace of progress has shown no sign of slackening.
An Historical Review of the Ex-Meridian Problem
Authors: Cotter Charles H.
Published: January 2010

The method of finding the latitude of a ship at sea from an observation of the Sun or other body near the meridian is practised extensively in the Merchant Navy. The history of the method, which dates from the middle of the eighteenth century, is full of interest: and the ex-meridian problem is almost as celebrated in the history of nautical astronomy as the double altitude problem. Considerable attention was devoted to the ex-meridian problem during the last century—a period which was, in truth, the golden age of astronomical navigation. Many ingenious solutions were contrived and a diversity of ex-meridian tables were constructed, all aimed at facilitating the problem of finding latitude at sea.
The use of radar: a practical suggestion
Authors: Oudet L.
Published: January 2010

Very shortly after the second world war merchant seamen found that they had inherited a device which shipbuilders and owners fondly imagined would prove to be an infallible safeguard against navigational hazards: this was radar. After fifteen years had been devoted to examining the disappointing results provided by the new panacea, the International Conference on Safety of Life at Sea, held in London in i960, finally published a radar code. So eagerly had this code been awaited that the Conference recommended its issue without waiting for the new international convention to be implemented.
The Jet Stream
Authors: Chambers E.
Published: January 2010

For many years there has been evidence (for instance from pilot balloon ascents and drift of cirrus clouds) of the existence of occasional very strong winds in the upper troposphere. However, it was not until about 1933, that Bjerknes, who had introduced the concept of the polar front during the first world war, produced a map of geostrophic wind deduced from upper-air temperature soundings made at a few scattered stations and showed a core of strong westerly winds at about 12 kilometres in middle latitudes in winter. No further progress was made until during the second world war when a comparatively large number of upper-air stations were set up and it was found that narrow belts of very strong winds were almost always present over some part of the Earth's surface in the 30,000/40,000 ft. altitude band. In 1944–5 American bombers encountered some rather frightening winds over the Japan area and since that time some extensive investigations of jet streams have taken place.

The term jet stream is popularly applied to any strong upper-wind current (of say 80–90 knots) and it is safe to assume that such winds are in fact associated with a jet stream, which may be considered as a narrow tube containing very strong winds embedded in the surrounding atmosphere.
Aircraft Navigational Errors
Authors: Proctor J. D.
Published: January 2010

C. S. Durst has tried to discover the frequency distribution of aircraft navigational errors from D. C. Willis's data. But how reliable are Willis's data for this purpose?

D.R. errors and track-keeping errors are differences between assumed and true positions. Evidence of assumed position is ayailable, but how can true position over the Atlantic ever be discovered accurately? Willis estimated true position by post flight analysis of navigational and meteorological data, but any such analysis must be based on some doubtful assumptions, for instance that compass error or wind was constant between fixes or that the true position was at the ‘middle’ of a ‘reliable’ fix. The analysis must also comprise many delicate judgments, for instance that the true position was at A, not B, because if it were at B an abnormal wind change must have occurred for which there is only slight evidence.
Chartwork in Small Craft
Authors: Vendrell J.
Published: January 2010

Having had for some time to navigate small craft in all weather in the western approaches to the Clyde and on the west coast of Britain, the writer would like to submit for the consideration of other small-craft navigators some modification in chartwork which has proved useful, especially in rough weather when parallel rulers are an abomination and flying dividers can be lethal.

On a violently moving platform the navigator can only work with maximum efficiency when he is himself chocked off in a position in which he is sheltered, has the widest possible field of view, can take bearings and can brace himself securely to leave both hands free to carry out a limited amount of geometrical plotting with reasonable accuracy. The obvious position is of course the fore part of the wheelhouse, where there is very seldom sufficient room for a fullsized chart table with all the frills and trimmings.
Time and Frequency Standards
Authors: Jones Harold Spencer
Published: January 2010

The quartz clock has made possible a notable improvement in the precision of timekeeping, with the additional advantage of providing a standard of frequency as well. This is perhaps putting the cart before the horse, for the quartz crystal oscillator was developed in the first instance as a precision standard of frequency; it was then adapted, by frequency subdivision and the use of a low frequency output for driving a phonic motor from which seconds impulses could be taken, to serve as a clock. It is primarily from its use as a standard of frequency that it is of navigational interest, for various radio aids to navigation, such as Gee, Loran, Consol and Decca depend upon accurately standardized frequencies. For the satisfactory checking of a frequency, comparison must be made with a standard whose accuracy is at least one degree higher than that of the frequency which has to be checked. Calibration laboratories, in turn, require to check their own standards. As the rotation of the Earth provides our fundamental unit of time, it follows that time, and therefore also frequency, must be determined from astronomical observations; hence it is necessarily the responsibility of the Royal Greenwich Observatory to provide both time and frequency with an accuracy sufficient for all practical requirements. The practical requirements have become more stringent in recent years, and that is why great efforts have been made to improve the precision of time determination and of timekeeping at the Observatory.
Tables for Astronomical Polar Navigation
Authors: Sadler D. H.
Published: January 2010

The special features of polar navigation are examined with a view to the design of tables for astronomical navigation in polar regions. The use of long intercepts and curved position lines is thoroughly investigated. It is shown that considerable economy of presentation can be achieved; as an example, a one-page table covering all bodies and both polar caps is given. Making the fullest use of polar astronomy, samples are given of permanent tables for the Sun and stars independent of the Air Almana.

The following critical review of tabular methods for astronomical polar navigation was written originally as a comment on a proposal to extend the Astronomical Navigation Tables (at present limited to latitudes between S. 79° and N. 79°) to the poles. Although it has been slightly amended, it has not been entirely recast and it therefore still retains some of the ‘thinking on paper’ of the original version. So far as is known the tables proposed are new, but there is clearly no great originality involved.
Controlled (h/d) Let-down using Barometric Height and Radar Distance
Authors: Downes J. G.
Published: January 2010

The method described provides glide-paths for climbing and descending aircraft by combining in a single instrument information from the barometric altimeter and radar distance measuring equipment. Preliminary flight tests have shown that the method provides a smooth path along which an aircraft can be flown within close limits, and is one that appears sufficiently promising to justify further development.

Height separation has for years been a fundamental concept in the control of air traffic. It is the basic method of preventing collision during en-route navigation and in some holding procedures. The main reason for this is that a suitable instrument already exists in the form of the barometric altimeter, aninstrument which is intrinsically more accurate and reliable than any of the usual navigational aids.
The Reduction of Sights in High Speed Aircraft
Authors: Everitt P. F.
Published: January 2010

When designing the periscopic sextant now coming into production it was realized that the conditions in the pressurized aircraft for which this sextant was designed differed sufficiently from those previously experienced to make it worth while reconsidering what methods would be most applicable to the new combination of pressurized aircraft and periscopic sextant.

The conditions differ from previous experience in providing (a) a higher speed; (b) very little, if any, direct view of the sky by the navigator.
Precipitation Static
Authors: Duncan P. F.
Published: January 2010

Static electrical charges from the atmosphere can in certain circumstances become attached to an aircraft in flight. This can prove dangerous to flight if radio aids to navigation are being relied on as the electrical charges result in precipitation static interference. The phenomenon was at first confused with the interference to radio resulting from transient atmospherics, although precipitation static interference is in fact largely of a continuous nature.
A Preliminary Radar Survey of the Humber
Authors: Milwright A. L. P.
Published: January 2010

At the request of the Ministry of Transport and the Humber Conservancy Board, a visit was made to the River Humber in H.M.S. Fleetwood to determine whether the navigational marks at present in use would be suitable for pilotage of the river in poor visibility by a ship fitted with a U.K. radar.
A Collision Warning Radar Display
Authors: Le Page L. S.
Published: January 2010

In present designs of radar sets for merchant ships, the radar-equipped ship is represented as being at the centre of its own P.P.I. picture. But there is a case for having an off-centre display. In this article are discussed possible advantages to be obtained from such a display, when the set is being used for collision warning away from a coast-line. The author recognizes that some of the opinions expressed are of a controversial nature.
Experience in Fitting Radar to Ships
Authors: Millard B. S.
Published: January 2010

Experience gained in equipping some 24 vessels, varying in size from 700 to 4000 tons, with radar may be of interest, and perhaps of help in avoiding some of the pitfalls that can occur.

The problem of finding sufficient space in a small ship so that one instrument does not interfere with another is never an easy one. For example, to fit radar to a vessel whose wheelhouse superstructure is not more than 10 ft. long may entail building a radar tower of considerable height if the proper distance between the scanner and the magnetic compass is to be maintained. The magnetic effect of the tower on the compass will then have to be considered, and it may be necessary to build it of a non-magnetic material. Also the effect of the radar, when working, on the D.F. loop arises; a distance of 12 ft. between them is here necessary.
Radar in Ships of the United States Lines
Authors: Andrews A. H.
Published: January 2010

This paper described how 53 ships of the United States Lines had been fitted with 10 cm. radar and how instructions for maintenance and operation were given by the Company and the manufacturers of the equipment. Instruction in its use is given by a representative of the manufacturer, and subsequently minor adjustments and fuse replacements are made on board, all other maintenance being done under service contract in port.

General instructions sent by the Marine Superintendent to the Master of each vessel fitted stressed the following points:

i. For the present the equipment is to be regarded solely as a collisionwarning device.

ii. The installation in no way relieves the Master from conforming to the Rule of the Road or any Pilot Rules.

iii. A complete radar log in which maintenance and operational work are recorded should be kept.

iv. Deck officers should acquaint themselves with the use of the equipment and should be encouraged to read the manufacturer's descriptive and operational booklet.
Some American Views on the Operation of Marine Radar
Authors: Isbister E. J. , Griswold W. R.
Published: January 2010

More than 1200 American radar equipments have been fitted to ships and this paper gave same American views on its operation; the views put forward were not necessarily different from those held in this country but certain experiences of inland navigation and blind pilotage which would be new to British operators were described. It was stated that when commercial production of marine radar started in the U.S., opinion was divided on the relative merits of 3 cm. and 10 cm. radar, some manufacturers concentrating on one and some on the other. Although 10 cm. equipment is still manufactured, all manufacturers now have a 3 cm. radar in production.

Certain advantages of radar assisted navigation were mentioned and these included the ability to determine another vessel's course and speed by plotting and the considerable saving in fuel and time that could be achieved by the accurate knowledge of the ship's position in coastal waters no matter what the weather.

Anomalous propagation in the Great Lakes region was described as being so common that shipmasters often regard the increased range of radar in the area as being the normal range of the set.

The use of radar by tugs on the Mississippi and its tributary the Ohio was described. Here up to fifteen barges of 100 ft. are ‘shoved’ by the tugs into narrow locks in weather which sometimes conceals half the tow. The small bump in the trace, representing the lock, is recognized by the pilots. One of the outstanding problems of this form of radar navigation was stated to be that the bridges (of which there are 1700 over the Mississippi) were such good reflectors that discrimination between them was not possible at a mile, at which distance the tow gets into position to pass between the piers.
The Present Outlook
Authors: Hansford R. F.
Published: January 2010

It may be useful at the end of this symposium to ask broadly what has been achieved so far in the field of navigational radar and what are the outstanding problems.

In this country alone, in the four years since the end of the war, rather more than 300 commercial radars have been manufactured to an exacting specification and fitted to merchant vessels, and a much larger number has been produced in the United States; during 1949 the British radar industry states that it hopes to fit more than a ship a day.