bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collision and the Perspectivity
Authors: Bell Frank Coffman 
Published: January 2010

Captain W. Burger and Captain A. G. Corbet in their general comment on the meeting of the Technical Committee in London, 16 April 1969, gave a curious and instructive hypothetical example of end-on encounter, a problem in navigation which they and others have found by experiments to have importance and practical difficulties. Their example is set in surface navigation at sea, and especially when using radar in fog. Two ships close with each other (in their example head-on and green-to-green), the two tracks being straight and parallel, and separated (in their example by half a mile). Should both ships stand on? My answer is affirmative, my argument difficult.If one makes the fruitful assumption that neither ship in this example alters course or speed, and then tries to plot The Edge [ of regression of The (mutual) Line (of bearing)], he discovers that the result is not a non-singular parabola, but rather simply a fixed finite point, i.e. at best a degenerate parabola—yet clearly there can be no finite collision, and collision at infinity is an empty threat. What do plotters of The Edge make of this paradox? Here handbook summaries will not do.
Captain Mário Gama's Direct Method for Star-sight Reduction
Authors: Cotter Charles H. 
Published: January 2010

In a very interesting paper which appeared recently the author, Capitão Mário Gama of the Portuguese Merchant Navy, describes a direct method for computing position lines from star (or planet) observations.The principal feature of Captain Gama's method is the systematic manner in which he arrives at an intercept to the extent, not only of saving time in sight reduction, but also in reducing the possibility of blundering.The method employs the Computed Tables of Altitude and Azimuth (HD 486) and involves timing a series of star-sights, the ship making headway meanwhile, by means of a stop watch which is set at zero at a noted chronometer time shortly before the observations commence. The following example, given in the original paper, in reducing sights of Vega and Denebola observed during morning twilight of 25 Feb. 1959, in D.R. position Lat. 10°10′ S., Long. 73°48′ E., will serve to illustrate the method.
Amendments to the Rules
Authors: Cockcroft A. N. 
Published: January 2010

A Great deal has already been written about possible amendments to the Collision Regulations, but as there may be an international conference on the subject in 1972 the various schemes should be discussed as much as possible so that their advantages and disadvantages will be fully appreciated.Criticism of the present Steering and Sailing Rules is mainly concerned with Rule 21. Disadvantages of this rule include the following:(1) If a giving-way vessel on a crossing course takes no action the privileged vessel must not act until collision cannot be avoided by the giving-way vessel alone. By such time collision is likely to be inevitable.(2) Small sailing vessels which may not easily be seen, especially at night, are required to maintain course and speed for large power-driven vessels.(3) High-speed vessels such as hovercraft are required to maintain course and speed for low powered ships crossing from the port side.(4) No provision is made for different types of hampered vessel approaching one another so as to involve risk of collision. If deep-draught vessels in certain areas are to be included in this category in the future the question of priorities may have to be considered.
On the Avoidance of Hurricanes
Authors: Hilder Brett 
Published: January 2010

For many generations mariners have been taught the law of storms and the rules for avoiding their centres. This paper describes some of the practical difficulties of avoiding hurricanes in the south-west Pacific area, and the failure of meteorologists to appreciate the dangers and difficulties of the mariners.About half the tropical storms observed conform roughly to the parabolic track of the law of storms. They form about 10° South of the equator during the north-west monsoon, (from December to April), and travel west-south-west, south-west and south-south-west as they gather strength and speed to a maximum; at 20° South they pause, recurve through south-south-east and south-east as they diminish in force and pass out of our consideration at 30° South.
Yugoslav Activity in the Design of Tables for Astronomical Navigation at Sea
Authors: Sadler D. H. , Scott W. A. 
Published: January 2010

The publication of Captain Flego's tables, which are of some theoretical interest, focuses attention on recent Yugoslav activity in the design of tables for astronomical navigation. The opportunity is therefore taken of adding to the review of these tables an account of S. M. Kotlaric's book; this was published in 1955 but has not previously been noticed in the Journal. English titles are used below.It is sad to announce the death of Captain Frane Flego, after a long illness, on 21 November 1957, after this review had been written. During a brief correspondence he was able to explain one or two points about his tables in rather more detail. The authors acknowledge much assistance during correspondence with S. M. Kotlaric.
The New System of Coordinated Universal Time
Authors: Sadler D. H. 
Published: January 2010

The purpose of this article is twofold: firstly to give readers a general account of the new time-system that will be introduced on 1 January 1972, and secondly to give greater detail in respect of the corrections that a relatively few navigators may need to apply.The great majority of users will not be (and need not be) aware of any change.In his paper ‘Time Data and Navigation’ (page 13 of this Number) H. M. Smith has given an excellent background to the change, but that paper was written shortly before the final details were agreed; a little background material is, however, repeated here.
Subsurface Navigational Hazards
Authors: Chanslor John W. 
Published: January 2010

1. Introduction. Nautical charts of many areas of the world carry notations adjacent to natural marine hazards such as ‘position doubtful’, ‘existence doubtful’, ‘position approximate’ and ‘reported (date)’. In spite of the development of precision survey and navigation systems, many of these notations must continue to be carried until the positions of the hazards are accurately determined or their existence disproved.The expanse of the oceans obviously precludes costly systematic hydrographic surveys in all areas, particularly in remote offshore areas. Although international cooperation in the exchange of hydrographic information assists in meeting modern charting requirements, the task of charting the seas may never be complete.
II—Inertial Techniques in Height Measurement
Authors: Whalley R. 
Published: January 2010

Inertial navigation techniques have been applied as a means of improving the height information in military aircraft for some time. It is almost certain that the supersonic transport will use inertial techniques for plan navigation and it is interesting to see how far it is worth extending this to include height, and also height rate, information.It is convenient to start by looking at the fundamental principles of inertial navigation as applied to height measurement; Fig. 1 shows the essential features. There will be an accelerometer measuring vertical acceleration; this must be maintained approximately vertical and can be very conveniently mounted on the main inertial platform. The output of the accelerometer contains a number of unwanted terms for which corrections have to be made. The expressions are well known and are explained in the Appendix.
Analysis of Long-Range Air Traffic Systems: Separation Standards—I
Authors: Reich P. G. 
Published: January 2010

This and the following paper by Mr. Attwooll are the first of a series which will describe the work of the Royal Aircraft Establishment on various aspects of air collision risk and traffic control. Mr. Reich's paper will be presented in three parts, the last two of which deal with the analytical techniques and how they are applied. Mr. Attwooll deals with methods of costing the effects of air traffic control deviations and shows how these costs are related to the size of separation standards. He discusses systems for both subsonic and supersonic transports.1. Objectives. The main task of air traffic controllers is to plan traffic flows so that aircraft are allotted sufficient separation to absorb not only systematic differences in speed but also the imperfections of navigation and piloting, which we term flying errors. To this end, they usually work with three separation standards, to be applied in, respectively, the along-track, across-track and vertical dimensions of space. The separation standard for any one dimension is the minimum intended (i.e. planned) separation permitted in that dimension when the intended separations are less than standard in the other two. The problem is to choose standards which are safe enough, but not so large as to lead to unnecessary traffic delays and deviations.
Costing Air Traffic Control Deviations
Authors: Attwooll V. W. 
Published: January 2010

1. Introduction. An air traffic control system maintains adequate separation between aircraft by requiring some aircraft to deviate from the paths which they would otherwise follow. In the absence of such deviations it must be assumed that civil transport aircraft would choose to operate at the most economical combination of airspeed, track and altitude (within the limits set by inaccuracies of weather prediction); A.T.C. deviations therefore involve economic penalty to the operator. It is important to assess the magnitude of such penalties for two reasons:(a) To provide a yardstick by which to compare different A.T.C. systems.(b) To give a measure of how much might justifiably be spent on new systems and equipment, to enable separation standards (and hence the penalty of deviations) to be reduced without reduction in safety.
Safety of Navigation on Inland Waterways in Europe
Authors: Beattie J. H. 
Published: January 2010

Most collisions on inland waterways occur in daylight and in good visibility and it is here there is most scope for improvement. Elaborate traffic control schemes such as that planned for the Panama Canal may not be suitable on European rivers where the density of shipping is very high and the nature of the traffic mixed. Local control may be feasible, but between control areas vessels will have to rely on self-contained aids, ship-to-ship communications and local navigational rules to avoid collision. The congestion of traffic, particularly at Customs clearance points, must be relieved.The paper discusses various aids to river-radar navigation, which are making fundamental changes in the methods on European inland waters.
Increasing Radar Target Information
Authors: Welsby V. G. , Davies D. E. N. 
Published: January 2010

Collision-avoidance devices are all based on the use of either electromagnetic or acoustic waves, although the former (i.e. radar) is of particular interest for this purpose.After reviewing briefly the fundamental theory which underlies all methods of detecting, locating and recognizing a distant target, reference is made to the successful development, in the Electrical Engineering Department of the University of Birmingham, of a narrow-band sector-scanning sonar system employing a multiplicative array to give improved target resolution. It has been demonstrated experimentally that the same principle can be applied to obtain a sector-scanning radar system capable of scanning rates as high as one million scans per second, which has applications for airfield surveillance radar. Attention is now being directed to the possibility of using wide-band signals, either to improve target detection and location for an array of a given size or to obtain additional information about the nature and behaviour of the radar target itself. Two possible methods of using wide-band signals are described.
Separation of Aircraft in the Approach and Departure Phases
Authors: Woodruff W. C. 
Published: January 2010

Separation of aircraft in terminal areas is made difficult by the convergence of tracks, continual changes of height, and traffic density. The application of longitudinal separation is too restrictive at busy aerodromes. Vertical separation is suited to the approach phase, but has limitations in the departure phase. The most useful form of separation is lateral, although it is often difficult to apply. The difficulties arise from organizational rather than operational causes and efforts to overcome them can be most rewarding.Other difficulties of a terminal area arise from the conflicting patterns of adjacent aerodromes, the mixing of terminal and overflying traffic, and the mixing of departing and arriving traffic. Lateral separation can assist in all these problems.
Flight Plans and Flight Programmes
Authors: Williams J. E. D. 
Published: January 2010

In areas of sufficiently high traffic density, air traffic control in some form will always be the primary mode of ensuring aircraft separation. Any traffic control system is concerned with separating aircraft in the future; therefore, the nominal separation criteria are determined by the accuracy of prediction of future movement of the aircraft and by the ability of the control system to correlate flight path predictions. The utilization of an airspace of a given capacity is determined by the distribution or flow of traffic.The accuracy of prediction depends on track-keeping and maintenance of planned ground speed. Since improvements in track-keeping will be limited for some time by past I.C.A.O. decisions on short-range navigation aids, attention is directed in this paper to maintenance of flight-planned ground speed. The effect of this on the operating cost of a modern jet airliner is examined and compared with the cost of flying at minimum cost mach number at a less than optimum altitude. It is concluded that in a crowded airspace, speed maintenance is preferable in short-range operations.The increase in space utilization by flow control is illustrated for a simple model, showing that speed control by A.T.C. increases utilization of a space capacity, which has already been increased by speed maintenance.
Collision Avoidance in the Air
Authors: Fairbairn E. P. 
Published: January 2010

In June 1958 the writer submitted to the Ministry of Aviation a paper, summarized below, on the avoidance of collisions in the air. The views expressed are his own and not necessarily those of the Company for which he works.1. The rules of the air should recognize that the information available to the pilot, whether obtained by visual or ‘electronic’ means, is likely to be limited by the following:(a) the pilot's ‘field of view’ is at most ± 90° in azimuth and some ± 20° in elevation relative to his aircraft heading.(b) a collision course can be recognized, but not the heading, course or speed of the other aircraft.
Anomalous Radar Propagation
Authors: Cooper G. R. 
Published: January 2010

Whilst steaming westwards at night along the coast of South Africa, echoes were received on the radar screen that gave the impression the vessel was about twelve miles off the coast. At the time, the vessel was about thirty miles S. by W. of Seal Point.The radar set, a Decca Mk. 12, was operating on the twenty-five mile range. It was receiving strong echoes from a sighted ship seven miles away on the port quarter. The set had been switched on to clear an unlit buoy fitted with a radar reflector. The position of the buoy was about ten miles WSW. of the vessel's position.
Automatic Echo-sounding Systems
Authors: Ahrens E. 
Published: January 2010

Dr. Ahrens's paper, which was presented in a more extended version at the meeting in Paris, describes a number of ways in which automatic processes may be applied to, or operated from, echo-sounders.Knowledge of the depth of water is of secondary navigational value to the surface ship since (as compared with the submarine), she has no changes of course to make in the vertical direction. The present state of development of surface navigation systems makes the use of the depth as a method of navigation superfluous in all cases in which sufficient water is available, where there is no danger of grounding. It can, however, when the topography of the sea-bottom is known from accurate charts, be employed for checking and confirming the data determined by other forms of navigation.
The Rate-integrating Gyro as an Aircraft Heading Reference
Authors: Fraser D. O. , Lee J. A. 
Published: January 2010

A description is given of a floated rate-integrating gyroscope and of the way in which it may be used to provide a high-accuracy aircraft heading reference. The sources of error of the system are examined and the overall heading accuracy is estimated as being comparable with the distance accuracy of a doppler system. This paper was presented, on 15 January, at the same Ordinary Meeting of the Institute as the preceding paper by Green and Glenny.The advent of the high-accuracy single-axis floated gyroscopes which have been developed so rapidly over recent years, primarily for inertial navigation use, has raised the question of whether the accuracy of these instruments can be made use of in other applications. Can systems which have been employing the older established types of gyroscope benefit from the greater stability of the new type? If a direct change of instrument with no modification of the method of use is considered, the answer will in many cases be no. For example, an improvement in the accuracy of the north-seeking marine gyro compass may not be found rewarding with existing marine navigation techniques, as other factors such as the accuracy with which a ship can be steered would become limiting, defeating the advantage of improved compass accuracy. The introduction of the doppler system has created a different situation in the field of aircraft navigation. Doppler navigation equipment enables an aircraft's drift angle to be measured accurately. That is, the aircraft's track can be defined with an accuracy dependent on the accuracy with which its heading can be measured. In this new situation the overall navigation accuracy is limited by the accuracy of aircraft compasses. These have in general been magnetic compasses, given improved dynamic performance in later years by the incorporation of a gyroscope or use of an associated directional gyro but still dependent on the magnetic element for long-term accuracy. Such a direction reference, though simple and reliable, is at no time precise by modern standards, and as the region of the magnetic pole is approached it becomes practically of very little value. For this reason in recent years the technique of using a free gyro alone as a long-term memory, to store direction information, has been developed, particularly by the airlines operating transpolar services. It is a system such as this that can reap most benefit from use of the new gyroscopes.
‘The Effective Use of Airspace’
Authors: Southall A. W. 
Published: January 2010

It is almost two years since Wing Commander Dickie's survey (11, 259) emphasized the importance of improving methods of control so as to allow more movements in a given volume of airspace. Since then, much effort in many countries has been devoted to the problem. The magnitude of these difficulties is not surprising when it is recalled that, in addition to the professional difficulties of flying, navigation and control, various sections of industry are involved, and international agreement must be obtained. At every turn there are political and commercial problems which cannot be ignored by those responsible for initiating action to solve a very difficult practical problem. This note is written in an attempt to examine once again the various possibilities for improving airspace utilization, with the object of discovering some pattern which will lead to progress.It has been stated that at all times both the controller and the pilot must know the absolute ground position of the aircraft, but it is by no means clear that this really is a requirement. It could well be sufficient to maintain the position of the aircraft relative to the traffic pattern, for this would satisfy the pilot's aim which is to travel in accordance with his flight plan, and also the controller's aim which is to ensure safety while making best use of the available airspace.
Aircraft Accidents and High Ground
Authors: Freer T. 
Published: January 2010

In recent years there have been a number of accidents caused by aircraft flying into high ground. The aircraft were mostly on nonscheduled rather than scheduled flights. This has resulted in much publicity being given to such questions as the licensing of the operators, the sufficiency of the radio or radar carried, and the route-experience of the pilots. These questions are of course relevant, but there is one further question which ought to be investigated and which has received little attention: it is the adequacy or otherwise of the means employed to show relief on charts.Under present policy the only picture of the relief is on topographical maps (Fig. 1), but it is on charts (Fig. 2) that the route and aids are shown. If the pilot is to check his safety-height in the air, he can do so only by coordinating the maps with the charts. This is cumbersome when he is pressed for time, and generally he does not do it; he flies on the charts using flight altitudes that have been pre-calculated, and the maps remain in the navigation bag unused.
The Treatment of Navigational Errors
Authors: Anderson E. W. 
Published: January 2010

In recent years, the most striking development in the philosophy of navigation has surely been the change in attitude towards errors. Ten years ago an error was regarded as something that just did not happen in the best navigational circles; today we accept it as the normal concomitant of observation, and we study to reduce it.This change in philosophy is really nothing more than theory following in the footsteps of the practical man, for the practical man has always regarded a position plotted on a chart with a certain amount of healthy scepticism. It may therefore be of value to discuss the whole business of errors from the point of view of the practical man, avoiding complicated mathematics and dealing in demonstrations rather than in rigid proofs. Navigation has been described as the business of conducting a ship on its way across the sea or an aircraft on its way across the sky. The word conducting implies safety. Indeed, safety is the keyword in navigation.
The Refraction Table in theAir Almanac
Authors: Sadler D. H. 
Published: January 2010

A description is given of the basis and method of calculation of the new table of refraction included in theAir Almanacfor 1943 onwards; the table caters for heights up to 55,000 ft. and all altitudes above the visible horizon.As already announced theAir Almanacand theAmerican Air Almanacwill become a single publication, under the title of theAir Almanac, as from 1953. To cater for the greater heights at which aircraft now fly, and for the possible use of observations at very low altitudes, the refraction table has been completely redesigned. The explanation of the table in the Almanac is naturally restricted to instructions for and illustrations of its use, and, in view of the current interest in refraction, especially at low altitudes, it seems desirable to place on record a full description of the theoretical basis of the table and of the method by which it was calculated.