bluuebunny/crossref_metadata_2025 huggingface dataset:
The Instrumental Accuracy Required for Barometric Drift Estimation
Authors: Parker J. B.
Published: January 2010

The effect of instrument errors in the basic pressure pattern formula (I) has been discussed. Calculations have been based on a 150 n.m. distance interval between altitude determinations, and the permissible instrumental tolerances are wider if the length of this run is increased. A particular latitude of N. 50° has been assumed, but this involves no loss of generality since ageostrophic errors and those due to the latitude term in the formula are believed to be compensatory. In general, both ageostrophic errors and pressure altimeter errors increase together with altitude, and if instrumentation is adequate for 10,000 feet (the level for which the probable error of 3 knots holds good) it will be so at higher levels. It appears that satisfactory results may be obtained by using a Mk. VI radio altimeter together with a Mk. XIV Kolsmann pressure altimeter, and taking the mean of four observations of D at the beginning and end of the run.
A Critical Table for Sextant Corrections
Authors: Worlledge J. P. G.
Published: January 2010

It is the present usage by the National Physical Laboratory and the Trade to give, on its Certificate, the ‘constant’ (graduation and centring) errors of a sextant only at stated points on the scale. If these errors are of a magnitude which is worth while applying as a correction, this usage is not quite what the user requires. The N.P.L. Class A Test, issued for instruments reading directly to 10″ (or o′·2 in the case of decimal subdivision) allows combined graduation and centring error up to 40″ or 4 scale divisions of the micrometer or vernier; the Class B Test for instruments graduated to 20″ permits such error up to 2′ or 6 scale divisions. Thus, even with instruments that pass these tests, it may be worth the marine navigator's while to apply the error as a correction. What he wants to know, however, are the limits of such errors as are worth his while to apply. In other words, he requires a Critical Table of Corrections, of the type used in the Air Almanac and in certain mathematical tables by L. J. Comrie, by whom, it is understood, the method was introduced.
A Precession Table for Correcting Astro Fixes
Authors: Jessell A. H.
Published: January 2010

When astronomical sights have been reduced by means of tables calculated for a fixed equinox, it is necessary to make a correction for the precession that has occurred since the date for which the tables were calculated. In the Astronomical Navigation Tables this correction is applied to each intercept separately. It is, however, possible to apply the correction once only to the fix obtained. This would probably be simpler, particularly with such tables as the Experimental Air Navigation Tables and H.O.249.
A New Aeronautical Plotting Chart
Authors: Freer T.
Published: January 2010

In an earlier paper it was suggested that developments in air navigation had created a requirement for a new form of air plotting chart. The chart illustrating the present paper was produced experimentally by one of the airlines to fulfil this requirement. The main factors taken into account in designing the chart were as follows:

(i) The air navigator is always working against time. He therefore requires his plotting chart to show as much navigational information as possible, so that he need not spend time looking things up in books or transferring information from other charts.

(ii) The scale must be limited by the requirement for easy handling in the cockpit, especially when the chart is intended for use in aircraft that have no navigation table.

(iii) The design of a chart that has to show as much information as possible on a small scale is chiefly a problem of avoiding congestion. The items that might be shown therefore require careful consideration and only those that make a justifiable contribution to the chart's navigational purpose should be included.

(iv) When flying under visual flight rules (VFR) the navigator's problems are less acute than under instrument flight rules (IFR). The chart should therefore be designed for IFR; it will always be adequate for the easier case of VFR.
Some Notes on Astronomical Observations at Sea
Authors: Sharpey-Schafer J. M.
Published: January 2010

In view of the appeal for observations that has been issued by the Institute to assist in the determination of the accuracy of astronomical observations at sea, it may be of interest to navigators to recount some of the experiences of a hydrographic surveyor. Large regular surveys usually depend on geographical positions which are obtained on shore with accurate instruments. In cases where surveyors fix these positions with astrolabes, or occasionally theodolites, three observers will probably have taken observations of some thirty-two stars each. In the analysis, intercepts of the order of 4–6” are obtained, and the final position is probably accurate to about 1”. Some hydrographic surveying, such as a one-day search for a reported shoal out of sight of land, various minelaying and minesweeping operations out at sea, and the determination of oceanographical stations on long passages, however, demand ordinary sights taken in the normal way at sea. The value of the hydrographic operation may depend on the accuracy of these sights, and therefore the report on the operation generally attempts some assessment of their accuracy. Considerable care is taken to achieve accuracy and often the ship is stopped and the sights referred by range and bearing to a moored beacon, even in depths of 500 fathoms. Methods of determining the accuracy obtained may be by taut-wire runs from known points of land or taut-wire distances interconnecting several beacons. Failing, or in addition to, these methods, two to four observers' results may be compared, or Sun and star sights can be referred to the same beacon; even short tautwire or patent-log runs to well-defined and previously well-fixed fathom lines have been used.
An Experimental Study of Drift and Leeway
Authors: Hiraiwa T. , Fujii T. , Saito S.
Published: January 2010

A ship will drift regardless of whether she is stopped or underway due to the action of the wind and sea. A knowledge of this movement is necessary in order to correct the course, to deduce the estimated position, for manœuvring at slow speeds and for search and rescue work. The causes of drift are the force of the wind on the upperworks, drift current whose strength depends on the wind, rolling which is caused by the action of sea and swell and, finally, ocean currents and tidal stream currents. To study the effect of wind on drift an experiment was carried out in which this effect was isolated from the other causes mentioned above.

A salmon drifter was used in which a gill-net was observed by radar from the time of the net being shot until it was hauled in. The net was then allowed to drift with the ship with the ocean current, the tidal stream current, the drift current and the wind and sea. The ship itself, however, was also subject to drift from the wind whereas the corner reflector on the net (which was several miles long) was not subject to this effect, the net acting as a sea anchor. It was thus possible to isolate the effect of wind drift.
Newtonian Inertial Navigation
Authors: Bell Frank Coffman
Published: January 2010

Newton'sPrincipia contains a neglected passage, which is nevertheless the true source of inertial navigation, occurring in De Motu Corporum Liber Primus, toward the end of ‘Sect. X. De Motu Corporum in Superficiebus datis, deg; Funipendulorum Motu reciproco’ as ‘Corol. 2’ to Prop. LIII. Prob. XXXV. Concessis figurarum curvilinearum Quadraturis, invenire vires quibus corpora in datis curvis lineis Oscillationes semper Isochronas peragent’. The corollary reads in the first edition:

‘Corol. 2. Igitur in Horologiis, si vires a Machina in Pendulum ad motum conservandum impressae ita cum vi gravitatis componi possint, ut vis tota deorsum semper sit ut linea quae oritur applicando rectangulum sub arcu TR & radio AR, ad sinum TN, Oscillationes omnes erunt Isochronae’.

This text shows only one or two very minor changes in the second and third editions, but the two extra drawings added in the third edition are helpful. Cajori, in a readily available publication quite adequate for reference here, gives these drawings, and his version of Motte's translation reads:

‘Cor. II. And therefore in clocks, if forces are impressed by some machine upon the pendulum which continues the motion, and so compounded with the force of gravity that the whole force tending downwards will be always as a line which is obtained by dividing the product of the arc TR and the radius AR, by the sine TN, then all the oscillations will become isochronous.’
A Philosophy of Navigation
Authors: Anderson E. W.
Published: January 2010

Six years ago, Mr. D. H. Sadler, in a memorable Presidential Address, answered the question ‘What is the Institute?’ This leads to the complementary and perhaps even more controversial question ‘What is navigation? What is its scope and its general pattern?’

If we look at the word Navigation in a dictionary, we may very well find that it is associated only with the sea. Today, of course, a much wider view is taken and the word is accepted as having to do with the land and the air and even with space. The definition: ‘the art of conducting a vessel on its ways’, may therefore be amended in words such as:

Navigation is the business of conducting a craft as it moves about its ways.
The Radar Simulator and Collision Avoidance at Sea
Authors: Quick J. H.
Published: January 2010

In order to provide facilities ashore for obtaining experience in the use of radar in conditions approximating to those at sea, a marine radar simulator has been developed by the Ministry of Transport as an aid to training. In this way, ships’ officers can obtain experience, particularly in the avoidance of collision, which could rarely be obtained at sea without endangering the ship. The instrument shows synthetic target echoes on a standard marine radar display and the effects of their movements and manœuvres. Helm and engine controls are provided to allow the observer to manœuvre as he thinks fit to avoid collision.

In this paper the Professional Officer and Chief Nautical Surveyor of the Ministry of Transport describes the simulator, the courses for ships’ officers that the Ministry has instituted, and the results of these courses. The paper, with three appendices which are not reproduced here, was presented at the Annual Meeting of the Ausschuss fur Funkortung held at Kiel from 12–17 September 1960, and is published with the kind permission of that body.
I—The Separation of Traffic at Sea
Authors: Oudet L.
Published: January 2010

To the layman navigation may sometimes appear as an old lady whose fads have acquired the sanctity of tradition. In every tradition, however, there is something venerable; and we would be very wrong to laugh at the traditions of the sea, for they are a legacy we have inherited from all our seafaring ancestors since the days of Noah.

The core of this inheritance is the notion of freedom. For centuries the freedom of the seas was absolute and unconditional; all men were free to use the sea, for no man can plant his flag on its restless immensities; and all were free to choose their routes and navigate as they pleased, for encounters at sea were so infrequent that it would be only a most uncommon stroke of ill-luck that produced a collision between two vessels in the vast emptiness of the oceans.
‘Fuel Reserves for Aircraft’
Authors: Proctor J. D.
Published: January 2010

The Working Party on Fuel Reserves for aircraft recommends that a major statistical attack should be made by a qualified body with the aid of an electronic computer on the problem of how to rationalize fuel reserves. I C.A.O's Standing Committee on Performance did much to standardize the risk of an aircraft hitting the ground on take-off and on landing, hence increasing profitability without prejudicing safety. Might not I.C.A.O. set up a committee to tackle fuel reserves on similar lines?

I think that even now, in advance of such a major undertaking, fuel reserves might be rationalized a little if certain information were available to flight planners and crews. For instance, Durst has given the accuracy of forecast mean equivalent head winds for a few routes (this Journal, 13, 288); if it were given for a wider selection of routes, perhaps the fuel reserve carried for ‘navigational error’ could be roughly specified as the extra fuel needed to cope with 95 per cent (say) of the errors expected in forecast M.E.H.W. The use of extra fuel enroute for other causes is much less frequent (on piston-engined aircraft anyway) and could generally be covered by change of destination or by use of fuel nominally carried for diversion.
I.—Research on Human Behaviour in Steering Large Ships
Authors: Hooft J. P. , Paymans P. J.
Published: January 2010

Three aspects of the controllability of a ship may be distinguished:

(i) The intrinsic manœuvrability of the ship. Requirements can be stated in terms of the manœuvres the ship can perform by means of its own control devices.

(ii) The environmental boundaries. It can be ascertained whether the manœuvres as determined in item (i) compare with the area (for instance in a harbour) available for the manœuvre. Requirements can also relate to the manœuvrability of the ship in reaction to environmental disturbances and their compensation by means of the ship's control devices.

(iii) The human ability to perform the manœuvres of which the ship is technically capable in the area available.
Captain Vancouver and the Lunar Distance
Authors: Emmott N. W.
Published: January 2010

The British Nautical Almanac was first published by Nevil Maskelyne, the Astronomer Royal, in 1766 for the year 1767 and the chief table in it was of lunar distances, which were tabulated at intervals of three hours to the nearest second of arc. On the bicentenary of its publication the theory and practice of lunar distance observation and reduction were reviewed in this Journal.
Probability of Collision in a Model Collision Avoidance System
Authors: Hara K.
Published: January 2010

A basic concept for estimating the probability of collision for a ship navigating through a seaway with congested marine traffic can be derived by applying queuing theory to the relation between collision avoidance manœuvres and the traffic environment. Ships usually perform various ‘services’, such as altering course or collision avoidance, to other ships and geographical obstacles; the analogy of the collision avoidance system to queuing is that each arrival of another ship represents a ‘customer’ and each manœuvre of own ship corresponds to a ‘service’. A model for a collision-avoidance system was constructed analytically from queuing theory and expressed numerically, under assumptions based on traffic surveys and the statistical analysis of collision avoidance procedures at sea, in order to study the feasibilities of the model.
The Extraction of Information from a Radar Display
Authors: Turner R. J.
Published: January 2010

The comments of Captain Maybourn on collision-avoidance systems in his paper ‘The Pay-off from Improved Navigational Aids’ (27, 133) prompt me to make a number of observations. What information, in principle, are we able to extract from a radar display ? This information will, of course, be degraded by the system errors, but that is another matter. Some of the following comments may appear trivial but it seems to me that they are of fundamental importance and escape sufficient emphasis.
Behaviour Patterns in Encounters between Ships
Authors: Dickens D. A. G.
Published: January 2010

In G. R. Spooner's interesting if not important article (27, 265), a situation was described wherein a risk of collision was created by basic non-adherence to the Rules. Firstly, the intention of the officer-of-the-watch to alter course to port was wrong, whilst that of the Master, substantially to alter course to starboard, was right. Secondly, the action of the non-burdened vessel was in error in as much as she should have stood on in anticipation of the burdened vessel making a decisive turn to starboard. The fact that at the precise moment of ordering this turn the other ship altered to port need not have necessarily prevented the burdened vessel from altering to starboard and ‘taking a turn out’—a procedure adopted in many such instances as that under discussion.
K's and F's
Authors: Henderson Duncan M.
Published: January 2010

In the old Cunard Line the log-books on the passenger steamers had a K and an F column on the left-hand page of each opening. This was taken to mean, and in fact was so used, as Knots and Fractions (not fathoms as in W. E. May's article, p. 116, Vol. 27).

Each noon the junior third officer filled in the columns for the previous 24 hours, and each hour had the nautical miles and the fraction thereof expressed in cables which had been steamed, entered in the appropriate box. Thus the figures in the F column never exceeded 9.
Manned Space Flight Navigation Techniques
Authors: Henry Richard C.
Published: January 2010

This paper (which was presented at a meeting of the Deutsche Gesellschaft für Ortung und Navigation held in Berlin in April 1963) describes the navigational techniques of manned space flight as they are at present conceived by the National Aeronautics and Space Administration in the United States. Although the paper is written in a more or less popular form, it should be of wide interest to navigators in showing the lines along which thought on this subject is developing, in one country at least.
I—An Elementary Compound System
Authors: Powell C.
Published: January 2010

This paper is concerned with combining the information from a ground-based radio navigation aid (the Decca Navigator) with self-contained sources of dead-reckoning such as air data and doppler. The essentially complementary relationship between D.R. devices and a ground-reference radio system can be exploited so as to produce an airborne navigational system whose merit exceeds that of either component individually. There is, of course, nothing new in a proposition of this kind. It is suggested that a combination such as that of Decca and a self-contained dead-reckoning device can usefully be described as a ‘compound’ system since the whole is formed, to quote the relevant entry in Webster's dictionary, ‘by the aggregation of otherwise independent elements’.
Some Problems in the Navigation of Supersonic Aircraft
Authors: Polhemus W. L.
Published: January 2010

This paper, which was presented at a meeting of the Deutsche Gesellschaft für Ortung und Navigation held in Berlin on 24 April 1963, briefly discusses some of the factors which will affect navigation and control of supersonic transport aircraft. Attention is directed to the special problems of determining optimum flight path and estimating position and E.T.A. during three phases of the flight: acceleration, supersonic cruise and deceleration.
A Collision Index and the Control of Traffic
Authors: Anderson E. W.
Published: January 2010

This number of the Journal goes to press just before the third international Convention sponsored by the Institute with the Ausschuss für Funkortung and the French Institute of Navigation. As members will know, the theme of the present series of meetings is the prevention of collisions, at sea and in the air, by systems or methods based ashore or on the ground. An account of the meeting and summaries of the papers presented will be published in the next number of the Journal, and a selection of the papers themselves will be published in future numbers. Wing Commander Anderson's paper, in which he introduces the concept of a collision index by means of which travel risks may be related to the risks of other human activities, forms a suitable introduction to the series.
II.—Simulation of Anti-collision Problems
Authors: Reynolds L.
Published: January 2010

The object of this paper is to describe how anticollision simulation is employed at H.M.S. Dryad, the Royal Navy School of Navigation. The methods described are those used in the Navy but this paper has no specific military slant, nor do the anti-collision problems studied at Dryad spring exclusively from the naval environment. Ship safety is one of the fundamentals of seamanship where the naval and mercantile problem is the same; the Navy does not however suffer the same manpower limitations on board ship.
Traffic Engineering: Some Theoretical Considerations
Authors: Makishima Tsumotu
Published: January 2010

Recent work on marine traffic engineering in Japan was reviewed in four papers published in this Journal in 1971. In the present paper, which may be regarded as a sequel to these, Professor Makishima offers some theoretical comments.
An Early Portuguese Contribution to Air Navigation
Authors: Cotter Charles H.
Published: January 2010

A recent Portuguese postage stamp of interest to philatelists and navigators alike was issued to commemorate the fiftieth anniversary of an adventurous air flight over the Atlantic from Portugal to Brazil by two officers of the Portuguese Navy, Rear-Admiral Cago Coutinho and Commander Sacadura Cabral.

In a valuable memoir published in English as well as in Portuguese by the Club Militar Naval of Lisbon an account of the novel method of navigation adopted by the two aviators is given. In the foreword to the memoir we are told:

‘The use of points of reference through the line of the intended crossing, and the able and skilful modifications of the formulae of nautical astronomy, by which the observer may, before starting, prepare the greater part of his calculations, in this way leaving only another quite material [small] part to be done in the air, are the two original conceptions by which the astronomical navigation, with a sextant, can be done in the air with accuracy and comfort …’
Collision Avoidance Systems
Authors: Watt J.
Published: January 2010

I was sorry to have missed the two papers by Captain K. D. Jones and Mr P. J. Houseley on the above subject, presented at a recent meeting of the Institute, and the subsequent discussion. Fortunately both Captain Jones and Mr. Houseley have been kind enough to let me see copies of their papers and I would like to add two pieces of information which may be of interest with reference to Captain Jones's paper.

The first is in regard to the making of ‘the first decision’ in clear weather. Captain Jones says that most mariners on sighting a target decide on the risk, or the probable miss distance, by an accurate even if intuitive evaluation of aspect and range. (They must also take into account the relative bearing of the target and its speed relative to that of own ship.) For the purposes of his argument Captain Jones omits from the clear weather case the alternative method of using radar in assessing the risk or probable miss distance. Evidence on the comparative accuracies of these two methods may be of interest; a series of demonstration runs on the Predictor automatic plotting radar in Elettra lll in the English Channel provided an opportunity to obtain some such evidence.

On one occasion which I have in mind, under conditions of clear visibility in daylight, a ship estimated at about 2000 tons was seen about 45° off the port bow at a (radar) range of 7 miles in a crossing situation.
Wind Variations along a Glide Path
Authors: Harrold T. W. , Browning K. A.
Published: January 2010

A method of measuring wind variations along an aircraft glide path is described. The technique uses a ground-based pulsed doppler radar to measure the line of sight velocity of precipitation particles. At low angles of elevation this velocity is that of die horizontal wind component toward the radar.

Wind variations likely to be encountered by an aircraft as it lands or takes off from an airfield are estimated almost invariably from a nearby anemometer placed 10 m. above the ground. It is obvious that this wind is not fully representative of conditions at higher levels; however, winds other than near the ground are difficult to measure. This note describes a method of measuring the line of sight wind using a pulsed doppler radar and presents some observations of the wind variation along a path at an elevation of 3°, which is typical of the glide path of many aircraft. These winds are compared with those recorded by a nearby anemometer.
The Work of the North Atlantic System Planning Group
Authors: Blake D. A.
Published: January 2010

I propose to discuss the problem of long-range navigation from the point of view of the A.T.C. system planner and to describe in outline the work that has been done in the North Atlantic Systems Planning Group (N.A.T.S.P.G.). In this area there are tidal flows of traffic of relatively high density and there is inevitably a need to reduce separations as much as possible, consistent with safety, to ensure operating costs are reduced, or at least kept in bounds with anticipated increases in traffic. This requires a much more precise definition of an acceptable separation standard, and for future planning the establishment of a relationship between separation standards and navigational capability.
V.l.f. Techniques for Navigation
Authors: Jones S. S. D.
Published: January 2010

Mr. Blake has given us an outline of what is needed in the context of Navigation of Long-Range Subsonic Transports in the 1970's. I now intend to pursue the theme by saying what I think v.l.f. navigation techniques can contribute to the solution of the navigation problem. In particular, I want to talk very briefly about the contributions that we feel v.l.f. might make towards the particular problem of limiting the numbers of aircraft which creep beyond Mr. Blake's navigation tolerance ‘fringe’ in addition to, possibly, by adding navigational information, increasing the effective M.T.B.F. of the total navigation system.

Clearly, addition of equipment cannot reduce M.T.B.F. in the narrow sense of the term—more equipment must have more faults—but if one interprets ‘fault’ as the incidence of a navigation error beyond the specified limit rather than narrowly as an electronic malfunction, I do think that v.l.f. navigation has its contribution to make to effective M.T.B.F.
Assessment Conditions in the Evaluation of an Airborne Navigation Radar
Authors: Huddleston H. F.
Published: January 2010

The ability to map terrain by means of an airborne radar raises many possibilities. Some few years ago it was recognized that a mapping radar which scanned to the side of an aircraft (rather than ahead) might, additionally, have important military potential. The research described here concerns the early operator evaluation of a prototype sidescan equipment which promised, among other things, to permit accurate fix-point navigation at lower flight altitudes.

By recent standards our aircraft was to progress at a fairly gentlemanly rate, somewhat below the speed of sound. Hence the radar map, produced as a moving strip by a rapid photo-development technique, did not threaten to flash past the navigator's eyes at an impossible speed. Nor, in general, did we expect the operator to be provided with anything unsatisfactory in the way of briefing. What is more, the navigator would be able to devote his undivided attention to the radar material whenever a fix-point was due.
Effects in Omega from Propagation Variations
Authors: Burgess B. , Walker D.
Published: January 2010

This paper discusses some of the variations that occur in the Earth-ionosphere waveguide that can contribute to errors in the Omega lines of position that are used to obtain navigational fixes on a world-wide basis. Effects due to conductivity variations in the Earth's surface, night to day changes in the lower ionosphere, multi-mode propagation, and solar disturbances of the ionosphere are considered and attention is drawn to the use of the multiple frequencies transmitted in the Omega format to overcome some of these sources of error. The paper was presented at a Marine Navigation Symposium held in Sandefjord, Norway, on 24–26 September 1969 and is reproduced with the permission of the organizers. (Crown Copyright, reproduced with the permission of H.M. Stationery Office.)
Accident Black Spots in the Lower North Sea
Authors: Oudet L.
Published: January 2010

In this paper Commandant Oudet, who might well be called the architect of routing in the Dover Strait, discusses certain aspects of what has come to be known as the Sandettie problem, namely the emergence of a potential accident black spot at the north-eastern extremity of the one-way routes in the Strait. Various solutions are discussed, including the reversal of the direction of traffic flow in the Strait recently proposed by the Honourable Company of Master Mariners and supported by Trinity House. Commandant Oudet shows that this proposal, unless the direction of flow were reversed in adjoining traffic separation schemes, would have the effect of greatly increasing the number of crossings and encounters outside the Strait. ‘The remedy would be worse than the disease’, he concludes. ‘It would be better to abandon traffic separation altogether’.

Places where road traffic is particularly dangerous and congested are often referred to as accident black spots; and the term is beginning to be used in the same sense in a navigational context. At sea an excessive density traffic always involves danger, because it is impossible to build fly-overs, as on land, and so avoid crossings; all encounters and all crossings take place on the same plane.
Automation in Aircraft Navigation
Authors: Inglefield W. J.
Published: January 2010

Automation is generally embarked upon with the idea of improving the economics of some process, largely by reducing the manpower, but it may be used also as means of solving computations which would otherwise present an almost impossible task for ordinary human effort, or involve so many people that this also would entail problems of organization. It may be difficult to demonstrate that automation of aircraft navigation can cheapen the job by saving in manpower, but it can be seen that the same manpower can be provided with solutions to navigation problems which will improve the aircraft navigational capability, but which would otherwise have demanded more crew. Processing the data obtained from a navigation satellite might be so complicated as to be beyond the scope of what can be expected of human effort in an aircraft, and even if this is possible the time taken to compute the fix may make the information so out of date as to be of little practical value. It is quite certain that by introducing automation into aircraft navigation, the flight crew can be relieved of some tasks so that, particularly in respect of the captain, more time can be made available for the management of the aircraft. We are, in fact, dealing with the question of workload and, therefore, we must look at the size of the job and the time available to do it.
Automating Long-range Air Navigation Practices and Procedures
Authors: Perry I. T.
Published: January 2010

With the advent of increasing numbers of high-speed, high-altitude aircraft on the airways of the world, airlines, aircraft manufacturers, government agencies responsible for navigational standards and air traffic control, as well as military agencies are actively engaged in studies and action directed towards significant changes in longrange air navigation practices and procedures.

These changes have been dictated by the need to utilize to best advantage the ‘limited’ air space available on long-range air routes to each individual aircraft, because of the fantastic growth rate in numbers of aircraft operating the trunk routes of the world.

In order to limit the amount of airspace required around each individual aircraft separation standards are enforced by the various agencies responsible for control of air traffic along these major trunk air routes. These separation standards are based on longitudinal, lateral and vertical limits between adjacent aircraft. In order to ensure that operating companies and flight crews are aware of these requirements, appropriate legislation is introduced by either international or national agencies and promulgated in readily assimilable form in regulations, orders, or flight or operation manuals.
Temperature-difference Corrections for the Dip of the Horizon
Authors: Hasse Lutz
Published: January 2010

For some time there has been an interest in nautical circles in the effect of temperature-differences between air and sea on the dip of the horizon. In about 1900, from his observations on board K.K.S. Pola, Koss established a relationship between the dip and the temperature-difference between air and sea, and an attempt was made, without much success, to produce corrections based on this relationship. New observations seemed only to add new uncertainties. A recent comprehensive review of the subject draws the conclusion that for practical purposes it is impossible to calculate the dip from measured temperatures by means of theoretical or empirical formulas. Indeed it is not possible to calculate the dip from simple measurements of temperatures at a given point to within o′·1 or o′·2. Horizontal irregularities, especially of thermal stratification and of wave height, always cause deviations of the dip from its calculated value. Nevertheless it is sound practice to correct the mean dip for temperature differences between air and sea. An analysis of observations where there are large temperature-differences—i.e. cases where the correction becomes noticeable—shows that the dip is greater or smaller than normal if the air is, respectively, cooler or warmer than the water. Out of 179 observations made by the Institute of Geophysics at Hamburg University with temperature-differences between air and sea greater than 2°C, not a single observation did not obey this rule.
The Use of Low Frequency Radio Aids in Supersonic Aircraft
Authors: King V. H. , Groves W. E. J.
Published: January 2010

This paper first considers the characteristics of the supersonic transport aircraft (S.S.T.) as established by various international authorities and, on the basis of these characteristics, endeavours to deduce the operational requirements for a navigation system. An indication is then given of the extent to which low frequency radio aids (such as Decca and Harco) can meet these requirements in the subsonic, transition and supersonic flight regimes, whilst discussing the relationship of these ground-based systems to self-contained aids. The paper was presented, in a fuller version, at the meeting of the Deutsche Gesselschaft fiir Ortung und Navigation held in Berlin, 22–7 April 1963.
A Log-Book of Magellan's Voyage, 1519–1522
Authors: Taylor E. G. R.
Published: January 2010

Among many records of the first circumnavigation of the globe preserved in Spain is the log-book kept by the pilot who brought the Victoria home—under the command of Sebastian de Elcano. This pilot's name was Francisco Albo. He signed on in the first instance as master's mate of the Trinidad, Magellan's own ship, which did not return. Although a native of the island of Rhodes, he was thoroughly grounded in the Portuguese method of navigation—by observation of the noon Sun. It involved the use of a four-year table of declinations, and an English version of this very table and instructions was presented to Henry VIII about 1540 by Roger Barlow, who was urging an English participation in the new discoveries.
The Sun-Star Chronometer
Authors: Chilton Edward
Published: January 2010

The Sun-Star Chronometer described in this note has been developed by Raymond Nardin of Switzerland and Oscar E. Batori of the United States; it is manufactured by Ulysse Nardin and produced by the Batori Computer Company Inc. of New York. It contains interesting features which merit description.
Automatic Radio-celestial Navigation
Authors: Marner Gene R.
Published: January 2010

The accurate, continuous determination of position, heading and course at all times, under all normal operational conditions, would be very desirable. This ideal has not been achieved for flights or voyages of long duration, but the many developments of recent years begin to give some promise that it may be possible. For high altitude aircraft the continuous optical observation of celestial bodies offers an evident solution, and doppler systems can give continuous speed over ground. For ships, however, the attainment of such an ideal navigation system is difficult. The various shore-based radio navigation systems have made important contributions, as have the development of inertial techniques. In addition, automatic optical sextants have been developed which can be used in clear weather.
Constructing a Marine Radar to Operational Requirements
Authors: Davies B. R. , Brown L. W.
Published: January 2010

Once the performance requirements of the Ministry of Transport Specification have been met, there remains to be considered the arrangement of the equipment to enable the ship's officers to take full advantage of the high performance for which the specification provides. These considerations can be classed in three main categories: the method of presenting information to the navigating officer, the convenience of the various controls, and the facilities provided to enable superficial maintenance to be undertaken.
The Operational Value of Shipborne Radar
Authors: Wylie F. J. , Kaye M. W.
Published: January 2010

Some questions affecting the operational value of shipborne radar and on which there is, at the moment, no clear unanimity of view are discussed in this paper.

The best position for the console is discussed in the light of requirements which vary with the different uses to which a shipborne radar can be put. The advantages of a chart comparison unit are also considered and the conclusion is drawn that these can be more economically gained by other methods. In particular the use of P.P.I. photographs is advocated as a method of land echo identification which leaves the chart free for other uses.
Shore-Based Radar as an Aid to the Operation of Ferries
Authors: Price L. D.
Published: January 2010

This paper is confined to a non-technical survey of the particular application of radar to the maintenance of a fast schedule of ferry vessels operating across a busy tidal river. After some seventeen months' practical experience of this application it is possible to give some opinions of the value of radar as a commercial aid to navigation.

Wallasey Ferries operates a twenty-four hour service between Wallasey and Liverpool, and carries some twenty million passengers per annum.
Precomputed Altitudes
Authors: Black A. N.
Published: January 2010

P. F. Everitt (Journal, Vol. 2, No. 1, p. 49) has discussed the problem of precomputing sights but gives the impression that the A.N.T.s cannot be used for this purpose; this is not the case, provided of course that the accuracy of 1 or 2 miles obtainable from A.N.T.s is acceptable. My experience of the method described below is confined to marine use with Hughes' Tables, but the same limitation of being confined to integral degrees of latitude and hour angle applies, so the method is clearly applicable in the air. Provided that the observation is actually obtained, the extra work involved in computing the sight in advance is trifling, and there are often appreciable advantages.
A History Recording Radar Display with Prediction
Authors: Embling C. A. , Stewart J. P.
Published: January 2010

The paper describes a method by which ‘history’ in the form of tracks of all vessels appearing on the PPI is projected on a flat plotting surface, and the use that can be made of such information to ascertain either the true or relative tracks of all such vessels and also the effects of own ship alterations of course or speed or both on the relative tracks of other vessels.

In a recent survey of collisions and from experience on board ships it has been found that, in heavily congested waters and low visibility, even vessels with sophisticated radar equipment and associated plotting facilities and sufficient personnel may find themselves ‘saturated’. Vessels with simpler radar and plotting facilities and less staff consequently become saturated in less heavy traffic conditions.
Velocity Measurement in Tanker Berthing
Authors: Bulman P. J.
Published: January 2010

Dr. Bulman's paper (which is Crown copyright) was presented at an Institute meeting held in London on 19 February 1970 with the Hydrographer of the Navy, Rear Admiral G. S. Ritchie, C.B., D.S.C., in the Chair. The paper, which describes work undertaken by the Royal Radar Establishment on the measurement of ship movement for berthing very large vessels, was presented at the same time as the paper read by Mr. M. J. Tucker, National Institute of Oceanography, and the discussion relates to both.

When a 200,000-ton tanker hits a jetty at more than about 24 ft./min., that is, nearly a quarter of a knot, some damage is likely to be caused. However, the problem of measuring the speed of the ship starts much sooner than that. One could say that from the moment the log is retracted on entry to the estuary some other form of assistance ought to be made available. Traditionally pilots and masters have relied on visual estimation—on the appearance of the passing land and passing landmarks in order to judge the speed over the ground while travelling up an estuary. This has been adequate for smaller ships where the height of eye, length of ship, width of ship were all considerably less than they are now on the largest tankers, and where the critical velocities were higher. Now, however, it has proved very difficult to judge by eye the speed of a very large ship from a station some 80 ft.above the water to the accuracy required, the accuracy being of the order of ± 3 ft./min. It is in this spirit that the Esso Petroleum Company approached the Royal Radar Establishment (R.R.E.) some two years ago or so to tackle the problem.
II—The Use of Compasses in High Latitudes
Authors: Thomas A. V.
Published: January 2010

The Earth's magnetic field can evidently be divided into its horizontal and vertical components, the horizontal component being of more immediate interest to the navigator since it directs the compass needle in the horizontal plane. Whereas on the magnetic equator the full field is horizontal (about 0·400 c.g.s. units), in high latitudes, with the angle of dip between 60° and70°, H, the horizontal force, maybe about 0·180 c.g.s. units. At the magnetic poleHis negligible and, given the opportunity, the compass needle would point vertically downwards, the instrument then having no directional properties in the horizontal plane.
Blind Flying Panels and Instruments
Authors: Neumark O. W.
Published: January 2010

The British standard blind flying panel and its component instruments have for many years fulfilled a very useful purpose, but there are now a number of special operational requirements which this panel no longer meets. For instance, the probable general use of tail warning devices will make it necessary for the night fighter pilot to follow the violent evasive action of his quarry, and because of the higher speeds involved it is desirable that the pilot should be able to interpret his radar scopes himself rather than depend upon his navigator for directions.
The Application of Hertzian Radiometry for Measuring the Temperature of the Atmosphere
Authors: Broussaud G. , Fombonne P.
Published: January 2010

At present there is no means of measuring the external temperature directly from a fast aircraft. This temperature is calculated by using the formula To = Ts/(1 + 0·2M2), using the mach number M given by the static and dynamic measurements of pressures, and the ram temperature Ts, measured by a resistance or thermocouple element. At high altitudes and when M is high, precision ranges from 1° to 4°, and the time constant from 3 to 4 seconds.
Initial Alignment of a Moving Inertial Navigation System
Authors: Seeley Richard B. , Cole Roy Dale
Published: January 2010

This paper describes and discusses some of the techniques by which a moving inertial platform may be aligned by using external velocity measurements and also presents some of the major problems and error sources affecting such alignment. It is based upon the results of a 3-year study, of inertial and doppler-inertial navigation at the Naval Ordnance Test Station, China Lake, California, and, in general, applies to inertial navigation systems which erect to either the local level or the mass-attraction vertical. Although rudimentary derivations are made of the alignment techniques, the paper is largely nonmathematical for ease of reading. Emphasis is placed upon the major errors affecting the alignment. This paper describes and discusses some of the techniques by which a moving inertial platform may be aligned by using external velocity measurements and also presents some of the major problems and error sources affecting such alignment. It is based upon the results of a 3-year study, of inertial and doppler-inertial navigation at the Naval Ordnance Test Station, China Lake, California, and, in general, applies to inertial navigation systems which erect to either the local level or the mass-attraction vertical. Although rudimentary derivations are made of the alignment techniques, the paper is largely nonmathematical for ease of reading. Emphasis is placed upon the major errors affecting the alignment.
Errors of a Simple Doppler Computer due to the Spheroidal Form of the Earth
Authors: Williams J. E. D.
Published: January 2010

Doppler-operated computers which perform plane D.R. navigation are currently offered to the airlines. A datum track and distance to go are set; from the time of selecting ON, the computer resolves small elements of distance run (input doppler and heading reference) as follows:

Change in across-track dist. = element of dist. run × sin (actual tr. − set tr.)

Change in along-track dist. = element of dist. run × cos (actual tr. − set tr.)

These relations are true for a plane Earth.
The Possibility of an Altitude-Azimuth Almanac for Air Navigation
Authors: Sadler D. H.
Published: January 2010

It is generally agreed that the increasing speed of modern aircraft, together with the availability of short-range radio and radar aids, necessitates a fresh approach to astronomical methods; less accuracy can be tolerated in the calculations but greater speed is essential. There are three stages after observation : the derivation of the position of the heavenly body observed, usually from the Air Almanac; the solution of the astronomical spherical triangle, usually by means of reduction tables ; and the resulting plotting of the position lines and fix.
Methods of Plotting and Reduction
Authors: Everitt P. F.
Published: January 2010

Hitherto it has been the practice to compute the altitude and azimuth of a celestial body either for a D.R. position or a chosen position in the vicinity of the D.R. position and to compare the computed altitude with the observed altitude, the difference (the intercept) being marked off along a line drawn in the direction of the computed azimuth from the position used for computing, either ‘from’ or ‘towards’ the object; a perpendicular drawn at the end of the intercept is the position line of Marcq. St. Hilaire.
The Inadequacy of Present-day Methods
Authors: Chichester Francis
Published: January 2010

If astronomical navigation is only required to give a ten-mile accuracy, as Mr. Parker has suggested in his paper, then its use will be mainly that of a last-aid in emergency. Radio, however, will give this degree of accuracy and, since a radio operator will in any case be carried, will naturally be more popular. On the other hand if astronomical navigation can be made to give a ½-mile accuracy it will become immensely more valuable than any other long-range aid. In the first place the signal received from the stars is completely reliable (at the heights which concern the air navigator, variable refraction can be ruled out) ; it is wholly independent of the ground; it provides a universal coverage which is free and is controlled by a non-political Body; and it can provide an accuracy greater than that of the long-range aids except the limited-purpose systems such as Oboe.