A thorough investigation is normally made of all the circumstances relating to an air accident. In-flight collisions can be of particular interest and should certainly be studied by doctors and psychologists. The human factor is said to play a part in 55 to 80 per cent of all accidents, and is basically psychological rather than physiological.

The Russian Sputnik travels rather faster than the Mayflower or even a transatlantic racing yacht, and the launching of this artificial satellite is truly a wonderful achievement. I want to tell you why I think so, and what it means for the future.

The satellite, which was launched on 3 October, has already made 300 revolutions about the Earth. Its speed is about 17,000 miles/hour, which is about 280 miles a minute, and it makes one revolution about the Earth in 96 minutes—that is, 15 revolutions a day. Its track is inclined to the equator at an angle of about 65 degrees, so that at one time it goes up to the Arctic Circle, and at the other end of its path down to the Antarctic.

The introduction of the Mark 10 Decca promised certain advantages over existing types and it was therefore deemed expedient to examine the potentialities of the equipment, its operational accuracy and general suitability for airline operation. The Ministry of Transport and Civil Aviation in conjunction with British European Airways were subsequently involved in two series of tests which began in early 1957 and continued into 1958. These tests were designed to determine the operational suitability of the Mark 10 Decca receiver and, in addition, provide a direct comparison between the performance of Mark 10 and Mark 7 equipment. All the flights were made, by day and night, on B.E.A. routes within the cover of the English chain. Ample opportunity was afforded to study the equipment under typical service conditions.

The information contained in this paper is intended to show the reliance which a pilot or air navigator can put on his expected winds in different parts of the world, in different seasons and at different heights. From the outset it must be realized that the figures given are subjective, and, in some regions at any rate, may need modification as facilities for obtaining upper air information are improved. However, it is not thought that such modification would be great and it would certainly not alter the broad pattern which is shown in the data presented here.

‘There are no charts of any part of the world so accurate and no directions so perfect as not to furnish frequent occasion for revision and amendment.’ (From the title page of the Nautical Magazine, 1832.)

In March 1832 a new monthly was published, the Nautical Magazine. Subsidized at first by the Admiralty and the Mercantile Marine Fund, it was edited by Beecher who was the right-hand man to Admiral Beaufort in the Hydrographic Department. Part of the introduction to this first volume read as follows: ‘The principal feature of the work will consist of the particulars of those hidden maritime dangers which are too often fatal to ships. … Much information, of a nature highly valuable to mariners, is scattered about, destitute of any systematic arrangement by which it can be made available to them; but the pages of the Nautical Magazine will hereafter become the receptacle, in which it will be preserved for their reference.’

The following contributions are selected from contributions to the discussion on Wing Commander E. J. Dickie's paper ‘The Effective Use of Airspace’. The paper was presented at an Institute meeting held in the Royal Geographical Society's house on 21 March, and is printed in the last number of the Journal.

I remember on many occasions in my Service experience undertaking cross-country flights with a large number of other aircraft flying along exactly the same route at almost precisely the same time. These were usually navigation training flights and, therefore, to some extent the errors which arose might not be held to be representative of what one would expect to happen to seasoned airline operators. Nevertheless, it was a commonplace to find on such occasions, very shortly after taking off, that all aircraft became so scattered as often to disappear from each other's view completely. And yet, at each turning point and again at the destination they all arrived at the same time. I am sure that there is something to learn from this particular aspect of flight along identical or parallel tracks. I do not think a simple fore-and-aft radar indicator would provide the safety in flight which we are anxious to establish. I believe that a secondary radar, giving an all-round horizontal view, would probably go a long way to meet the stated requirement; although, of course, only one giving a spherical view could give 100 per cent safety. Even with pilots who can see exactly where they are going, along clearly defined tracks over country abounding in natural navigational aids, it is true to say that the really effective variable is the track and not the timing. This lateral scatter is due to inaccurate steering data and to the many other inaccuracies affecting the actual path of an aircraft through the air, quite apart from wind-finding errors. Even with the best primary navigational aids, tracks cannot be flown with absolute precision. It follows that collisions are at least as likely to arise from errors of track as from errors of timing. So I would suggest that what we really need is a secondary radar which will give us an all-round horizontal view and I think that we must not delude ourselves into thinking that even the finest primary navigation aid will provide an accuracy in the air by which all aircraft proceeding along one route will remain only fore-and-aft of each other.

The usefulness of radar plotting, as at present practised, may be considerably enhanced by the application of a doppler radar technique which gives instantaneous measurement of relative velocity components and quickens the whole plotting process. The range and bearing of the target are given by an ordinary radar PPI, from which the rate of change of bearing may also be determined. The doppler radar gives an immediate measurement of the radial component of relative velocity and the derivative of radial velocity: from these data the course and speed of the target may readily be determined, using an automatic computer if so desired. Possible errors in deducing the true aspect and speed are discussed and the mode of operation, and principal design parameters of suitable doppler radar are given.

Australia's place in Navigation is due, in several aspects, to her geographical environment. Her first discovery is still a navigational mystery, and her first appearance on world charts about 1530 was confused by thepolitical division of longitude between Spain and Portugal. To people in the western hemisphere the most famous names in navigation are those of Columbus, da Gama, Magellan and Drake. These men were all aiming at the rich trades of the Spice Islands, whether they made for the West Indies, the Cape of Good Hope, Magellan's Straits, or the North-West Passage. They were followed by a stream of men who preferred the well-known tracks to any leading into the trackless wastes and barren coasts or Australia.

Despite increasing use of radar, marine collisions have continued to occur in significant number. The principal reason advanced for this development has been the ‘human element’ and many new electronic innovations have been suggested or built to minimize this factor. This note is written not for the purpose of providing an absolute answer to the problem, but rather to suggest there may be another angle from which it may be approached.

The conventional Decca Navigator system is of the type in which pairs of stations generate patterns of hyperbolic position-lines. One station, the master, is common to each pair so that a chain of three stations suffices to provide the two intersecting position-lines required for fixing. Among the advantages of this arrangement are the absence of any limit to the number of users of a single chain and the compactness of the position-fixing instrument (the receiver) which can readily be installed in the smallest craft. These two features contribute considerably to the success of Decca as an aid to surveying as well as to navigation.

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.

It may not be humanly possible to draw up a code of rules for international use which are completely comprehensive and clear in every particular. The Rules for Preventing Collisions at Sea are not, and it would be useful to know the accepted interpretation of doubtful points. Criticism of the Rules is not here intended, and all references to the impact of radar upon their interpretation is omitted, as this question is now being studied by a Working Party. Suggested correct interpretations are added in brackets.

When a resurvey of New Zealand coastal waters was started by the Royal New Zealand Navy, it was realized that many areas could not be covered accurately by visual fixing of landmarks and would require accurately laid beacons. It was also known that if accurate radar ranging could be provided, then a reduction could be made in the number of beacons to be laid and in the time required for the survey. As the standard Admiralty survey radar type 972M was not available as a complete equipment the Dominion Physical Laboratory were asked to develop a radar. This paper outlines some details of the radar and the operational results after two years installation on board H.M.N.Z.S. Lachlan during the survey of Hawke Bay.

I Have read Professor Taylor's article with great enjoyment. There are, however, two matters of fact on which, though they do not affect her main thesis, the record should, I think, be set right, (a) The earliest experimental proof of the Earth's revolution round the Sun was neither Bessel's detection of the relative parallax of 61 Cygni, nor Henderson's determination of the absolute parallax of α Centauri (both of which occurred in 1838) but Bradley's very beautiful discovery of aberration in 1725, together with his slightly later explanation. The discovery was made in a deliberate search for parallaxes; and although that particular proof of the Earth's movement was not then achieved, it was at once recognized that aberration provided a different and equally cogent one. Bradley's work was indeed resisted, in some quarters and for a short while, for reasons which Professor Taylor will by no means find unexpected. His later discovery of one term in the nutation was also a discovery of something which would have embarrassed Ptolemy, and delighted Newton; it certainly tended to confirm the picture, if that were needed. By the time parallaxes actually were discovered, though there still were individuals, sometimes of high rank, whose prejudices were stronger than their intellects, the only point of genuine doubt was the question how far away the nearest stars really were.

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.