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.

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.

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.

Two years ago I gave an account to a meeting in this series of the establishment of Shackleton Base and of Theron's voyage (Journal, 10, 161). The second part of the expedition began with the sailing of the Magga Dan for the Weddell Sea and Shackleton Base. The ship, of some 1800 tons and 2000 s.h.p., with variable-pitch propellers, was built especially to withstand ice pressures. Even so, the Weddell Sea proved too much for her at one point; but fortunately not for long, and she was soon moving down to Shackleton, calling at Halley Bay, to see the British I.G.Y. base, and Emperor Bay, where an estimated ten-thousand birds gather and nest each year.

Captain H. Topley in his article on radar plotting errors (11, 167) has endeavoured to simplify the arithmetic and introduce an approximate formula which will be of practical use to the navigator. He admits that his approximation has limitations and it appears to me that some danger may arise from the difficulty which the non-mathematical navigator may have recognized when he has passed the point at which the formula will be safe to use. Further, Topley tends to concentrate on the errors in the estimated course and speed of the other vessel and to give rather less attention to the problem of errors in the closest position of approach (C.P.A.). The latter may be by far the most significant factor.

IT is not often that the exact meaning of the Collision Regulations is the subject of a dispute in a court of law. However, a translator would be shirking his duty if he were to put the easiest interpretation upon each phrase.

The author recently attempted to translate the Collision Regulations into the Urdu language. This article presents his main findings on the subject of drafting.

Two defects recur too often to be greeted at each encounter and it would be convenient to deal with them collectively. They are:

1. (1) The use of unnecessary words, and

2. (2) The use of different words to convey the same purport.