A description is given of the basic principles and method of operation of a single-channel automatic blind landing system developed by the Blind Landing Experimental Unit. The system uses the internationally accepted radio aid ILS for approach guidance to the point where more accurate information is required and then two new guidance elements, magnetic leader cable and radio altimeter, are introduced for the final landing. One of the great advantages of the system is its flexibility and if new guidance elements are developed the system will be easily adapted.

Extensive flight tests have been made in all weathers and the performance achieved is much better than that obtained in manual landings in good visibility.

In considering the application of the system to civil aviation the outstanding problem Is that of safety and reliability. Various suggestions are discussed briefly and the possible requirement for an independent pictorial monitor is mentioned. Early thoughts on a monitoring system are described.

Automation has proceeded much further in connection with air navigation and air traffic control than it has in comparable aspects of the maritime service. There are many factors to account for this. By its nature, air travel involves risks which are greater and more urgent than those of sea travel and which, in focal areas, are high in all conditions of weather; its passenger/cargo ratio is vastly greater and this inevitably stresses the need for every possible aid to safety. These characteristics and others more obvious lead to ground control, control leads to centralization and uniformity and thus to the ready introduction of advanced developments and their imposition where appropriate on the airborne user.

At the end of a conference held in London in June 1957 to discuss the avoidance of collision at sea and in the air, it was recommended that the three sponsoring bodies (the British and French Institutes of Navigation and the Ausschuss für Funkortung) should set up a representative Working Group to study the desirability of amending the Collision Regulations to take into account the use of radar.

The Group, which was formed in January 1958, was composed of the following members, not all of whom were able to attend every meeting: Commander P. C. H. Clissold (School of Navigation, University of Southampton), Captain W. H. Coombs (Honourable Company of Master Mariners, Barrister at Law), Captain R. Dublineau (Compagnie Générale Transatlantique), Captain P. Dupuy (Compagnie des Chargeurs Réunis), Captain H. Giessler (Ausschuss für Funkortung), Captain H. D. Harries (Regierungedirektor beim Bundesminister für Verkehr), Vice-Admiral K. Hoffman (Bundesverkehrsministerium), Professor P. Hugon (Professor Général d'Hydrographic, Rear Admiral, Ret.), Captain E. H. Ketels (Verband Deutscher Radar), Captain Le Bihan (Compagnie des Messageries Maritimes), Captain G. Lohmnitz (Norddeutscher Lloyd, Bremen), Captain P. Marchand (Ocean Weather Ship Service), Dr. F. W. Marienfeld (Bundesverkehrsministerium), Captain D. G. Tait (Honourable Company of Master Mariners), President Dr. R. Vogler (Bundesoberseeamt, Hamburg), Captain F. J. Wylie, R.N. (Director, Radio Advisory Service), Captain C. J. Wynne-Edwards, R.N. (Director, Compass Department, Admiralty Compass Observatory). The members of the Group served only in a personal capacity.

English sailors came more than half a century late into the world of transatlantic voyages and new discoveries. Nor should this surprise us when we remember the exasperating delays they had to expect when getting out of our long river estuaries into the narrow seas, and out of the narrow seas into the Atlantic Ocean. Once there they still had to encounter prevailing head-winds, where a Columbus had only to launch himself on the steady trade winds to discover America.

Disasters result from the breakdown of navigational faculties. Those concerned with the ‘practical’ aspects of navigation naturally assume a standard and infinitely flexible nervous system by which the individual can adjust to the stresses created by great speeds in the absence of habitual sense information. This paper outlines the nervous basis of adjustment to environment (personal navigation), the forms of breakdown in disease, and the nature of hallucinations. Some forms of disturbing experiences likely to be felt in modern navigation are predicted and explained. Such problems are seen as integral matters of aviation planning, design and practice.

‘The main aim … is to enable interested persons with quite different backgrounds of knowledge and experience, to come together and consider collectively a subject of common interest from their various standpoints.’

(A. M. A. Majendie, ‘The Significance of Blunders’, this Journal, 12, 28.)

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.

Most of the Ordinary Meetings of the Institute provide an opportunity for specialists to report on work that has been carried out, or experience that has been gained. From time to time, however, we have a meeting designed specifically for the purpose of discussion. The main aim of such meetings is to enable interested persons, with quite different backgrounds of knowledge and experience, to come together and consider collectively a subject of common interest from their various viewpoints. The present discussion is on the significance of gross human errors and blunders in navigation.

This paper, prepared by the Hydrographic Office of the United States Navy Department, and based on recent American experience, was originally printed on the back of the April 1958 Pilot Chart of the North Atlantic Ocean. It is reproduced here by kind permission of the Hydrographer of the United States Navy. A less extensive treatment of the subject, to which readers may like to refer, was given by L. R. R. Foster in the Journal in 1952 (‘Some Recent Work on Polar Navigation’, 5, 12). Figs. 1–12 are reproduced from the Polar Record (8, 1956–7) by kind permission of the Scott Polar Research Institute, Cambridge.

The first requisite of the embryonic ice pilot is to develop a healthy respect for the tremendous power of the ice. He must never permit the peaceful appearance of an ice-field to lull him into a false sense of security. On the other hand, he need not fear the ice, since a great deal of progress through ice can be made by a vessel in capable hands.

The idea of portraying the accuracy of a navigational system by means of contours is very old and was first introduced to readers of this Journal by Jessell and Trow. Later writers, Sameshima, Namikawa and Hasegawa, have published accuracy contours for Loran chains. This note is a further contribution in this direction and its aim is to investigate what sort of accuracy can be achieved by marrying a position line from one chain with a position line from another.

N. Sameshima has studied the accuracy contours arising from a hyperbolic system where position lines are obtained from two pairs of stations, each pair having one station, the master station, in common. Y. Namikawa and K. Hasegawa, in a later article, constructed accuracy contours for a number of Loran chains, mainly in the Pacific, but also in the Atlantic areas. This article discusses the more difficult case where fixes are obtained through using pairs with no common station, and indicates what improvement may be expected through introducing a fourth station in a number of selected instances.

The two books considered here, despite the romantic title of the larger and more ambitious one, are complementary both in subject matter and in interest. In The Sleepwalkers, Arthur Koestler offers us a highly un-conventional, and in detail controversial, history of man's picture of the Cosmos. But he brings it to a close with the Newtonian synthesis since this afforded a simple scheme satisfying to mathematician and layman alike. This, he claims, is the picture still accepted by the majority today, and as regards the ‘man in the street’ and the school textbook he may be correct. But during the present century there has been an accelerating series of amazing astronomical discoveries which in their earlier stages were excitingly presented to the reading public by Eddington and Jeans. Last year Professor Lovell, in the Reith Lectures, brought listeners up to date, and dealt briefly with the individual man's place within the vast dimensions now revealed.

Future transport systems are difficult to predict, but one can perceive three main possibilities. The first is that transport will become entirely automatic, so that where, for example, one now has an automatic pilot during flight, one will also have automatic take-off and automatic landing. Flights will be pre-programmed, and will require no supervision in the vehicle itself or even from a remote-control room. Whether or not such a system is practicable is not within the scope of this paper; but there does not appear to be any purely mechanical problem connected with it that could not be overcome. However the production of equipment of the necessary reliability raises formidable human problems. problems. Not the least among these is the difficulty of maintaining rigorous standards of inspection; another is the rationalization and speeding up of faultfinding and repair procedures. It looks as though if we were to dispense with the human element in one sphere, its importance in another would be enhanced.

Captain Majendie would restrict the use of the word blunders to those aberrations of human behaviour which cannot be attributed to any avoidable cause. For my purpose this definition is unduly narrow and I use the concept in a slightly wider sense, namely: ‘errors, or aberrations, without apparent cause’. An understanding of the underlying causes of blunders is essential to their proper study, and to the reduction of blunder rates. Assuming that these causes are factors of human behaviour, there should be some connection between the occurrence and causes of blunders in different fields of human activity. In the hope that this may be so, I summarize the conclusions drawn from investigating blunders over a period of 25 years with a staff of 20–30 engaged on numerical computation and proof-reading.

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.

The object of this paper is to summarize the results of air and sea trials that have been obtained in the first two years' operation of the experimental Dectra chain in the North Atlantic area. Reference is also made to observations at fixed monitor stations, and briefly to the Dectra data link for air-to-ground transmission of the Dectra fix.

Dectra, which stands for ‘Decca Track and Range’, is a long-range position-fixing system derived from the Decca Navigator. Early in 1957 two of the three transmitting stations forming a Dectra chain designed to cover the North Atlantic air routes were put into operation and flight tests began in March of that year; in the following October, air trials started using all three transmissions. Various tests at sea have also been carried out, although on a much less extensive scale than those in the air.

Certainly genuinely unavoidable aberrations in human behaviour exist. In surface navigation, however, these momentary blunders seldom lead to fatalities such as collisions or groundings, although in shiphandling they can cause collisions when coming alongside or when manoeuvring in a confined space, but usually only of a minor nature.

The examination in the R.N. Navigation School of some sixty collisions and groundings has revealed that in only two have aberrations played any significant part in the subsequent disaster. This is quite easily explained for two reasons. First of all ships at sea usually close one another or approach a danger at a comparatively low speed. Furthermore the prudent mariner reduces speed when danger exists and when the situation becomes tense. There is therefore usually time for the nature of a blunder to be recognized and for the necessary corrective action to be taken, which, if not resulting in immunity, will reduce the gravity of the incident. Sixty knots is an exceptionally high relative speed on the surface, yet this provides minutes for human reaction as opposed to seconds or even split seconds normally available in the air.

A new system of electronic scanning is described in which the narrow receiving beam of an acoustic echo-ranging equipment (i.e. asdic) is swept over a wide sector at a very high speed. Since the transmitted pulse covers the whole sector, and the scanning is done at least once per pulse duration, an effectively instantaneous search of the sector is made without any loss of information. The results of trials at sea are shown and possible applications to surveying and navigation are briefly discussed.

The use of underwater acoustic echo-ranging systems in the form of echo-sounders (as fitted on most ships nowadays) and asdics (as used, for example, for submarine detection during the war and now applied to whale-finding and fish-finding) is well-known.1 These existing systems use a single beam of acoustic energy, the pulse being transmitted by a transducer (or loudspeaker), and received, after reflection from the sea-bottom or whale or other object, by the same or a different transducer (this time used as a microphone). The time difference between transmitted and received pulses measures the range of the bottom or object, and is recorded on a chart by a stylus moving at a speed equal to the velocity of sound in water multiplied by the ratio of the width of the chart to twice the maximum range of detection. The transmission of the pulse marks the left-hand edge of the paper, and any echo received causes a mark at a point in the stylus sweep corresponding to the range of the object causing the echo. The paper is meanwhile moving at right angles to the stylus sweep, so that the next pulse transmission marks on a line adjacent to the previous one.

Colin Mudie was navigator of the ‘Small World’ transatlantic ballooning expedition and designer and maker of the ‘gondola’ in which the voyage was completed by sea after the balloon was forced down. Besides Mudie the crew, as many will know, consisted of his wife Rosemary, Arnold Eiloart and his son Timothy.

To be the navigator of a balloon is somewhat of a contradiction, for an aerostat or balloon travels only with the wind. Once it is airborne, navigation, in the sense of controlling or directing its path or course, becomes extremely limited. It is possible to search, by ascending or descending, for a wind-stream in another direction but the wastage of gas and ballast involved makes this impracticable for a flight of any duration. It is also possible to produce some slight effect on the down-wind course of the balloon by slowing its speed by means of a drag and using the resultant wind to slew the envelope sideways. A paravane might also be used over water, but the overall effect would be unlikely to amount to more than a few degrees. In fact the only time that the balloon navigator has any real choice of direction is at take-off, when he can either go with the existing breeze or stay put. Thus it is that for the balloon navigator more than any other perhaps the greater part of the navigation is done beforehand with reference to the wind forecasts and meteorological charts.

The primary Rule of the Road at Sea is to keep to the right in practically all cases. The single exception which comes to mind in regard to fully manœuvrable vessels under power is overtaking in a narrow channel, when the overtaking vessel should keep to port and take the risk of meeting any on-coming traffic, like the working rule on the roads ashore. The alternate use of true direction as a frame of reference at sea, suggested by Lieutenant-Commander N. L. Fendig, U.S.C.G. in this Journal (October 1958) would lead us from simplicity into confusion. The same confusion would apply ashore if the roads were marked with compass courses, and vehicles were to give way to eastern traffic, which would sometimes be on the right, and sometimes on the left hand.

The notes by Commander Clissold, R.N.R., under the above heading in the same Journal, are both sensible and workable, but hardly stimulating in nature, as they deal with tedious detail like the rules themselves, without calling for a new outlook. I find the basic Rule of the Road beautifully clear compared with the pages of exceptions and details, most of which show no correlation with each other, or to the basic rules. While I believe that the present rules are the best possible for fully manœuvrable powered vessels, those concerning vessels of limited movement are complicated with confused detail lacking a clear cut system based on relative manœuvrability.