In May 1948 the Radio Technical Commission for Aeronautics, a cooperative association of United States government and industrial air telecommunication agencies, issued a report outlining a comprehensive scheme for the development of air traffic control facilities in U.S.A. for the next fifteen years. This report was prepared by a committee set up by the R.T.C.A., Special Committee 31, and it is generally known as the SC31 Report. It was the result of a study undertaken at the request of the Technical Division of the Air Coordinating Committee, an inter-departmental committee established by the Secretaries of State, War, Navy and Commerce, and directed by the President to examine aviation problems of mutual concern and to develop and recommend integrated policies and actions to be taken for their solution.

A common feature of all systems of hyperbolic navigation (such as Gee, Loran and Decca) is the necessity of interpreting the instrumental readings of lattice coordinates and of transforming them into position—either directly into latitude and longitude or relative to neighbouring geographical features. Several methods are in use: elaborate tables giving latitude and longitude in terms of the lattice coordinates are published for use with Loran; chartlets, on a special projection, are available for certain routes on the Decca system; but the most generally useful form of interpretation, combining both presentations, is the latticed chart. This paper is concerned solely with the construction of such charts. Although formulae and examples are given, details of the computing techniques are deliberately omitted; it is hoped to issue a fuller account with the tables that have been prepared for the use of this method.

The basic procedures used by most airlines to compile their flight plans are very similar, and are by no means as simple as they could be. When a choice of routes exists it is the normal practice to compile a series of flight plans from which the one giving the most advantageous route in the prevailing weather conditions is selected. In the absence of a direct approach to the problem of selecting the best route, the method of comparing different flight plans is improved by increasing the number of plans; it is therefore desirable that a method of speeding up the process of compilation should be evolved so that a greater number of plans can be prepared. Also the increased aircraft speeds which are to be expected in the future, and the requirement to reduce fuel loads, especially fuel reserves, to a minimum call for some rapid method of modifying the flight plan on receipt of in-flight forecasts and observations.

The problem of how birds find their way can be examined by studying natural migration movements and also by forcing birds to undertake long journeys more or less under conditions which can be decided by the experimenter. The racing pigeon is an ideal subject for these homing experiments, but they have also been conducted with many species of wild bird and Fig. i shows some of the more remarkable flights that have been achieved with these. The use for these experiments of birds breeding in colonies has many advantages as large numbers can be caught and transported together, and their return watched for in a small area. Conspicuous birds such as gulls can be made individually recognizable by a code of plumage marks or by putting coloured leg rings on them.

Oceanography is concerned with the applications of all sciences to the study of the sea, and navigation, in its widest sense, with the application of any science and systematic knowledge to the purpose of maintaining safe and efficient communications across the oceans. They have something in common, but oceanographical work, whatever its future promise, is primarily academic, and navigation the application of well-tried conclusions. It would be wrong to suggest that basic studies of sea conditions are followed by systematic attempts to use them to improve navigation. Progress is sporadic, depending on individual enthusiasms and commercial enterprise as well as the efforts of government departments and professional associations. There is no sharp division between the basic work and its applications, or, after allowing for some extremes, between the scientist and the authority on navigation.

The problems of submarine navigation are entirely distinct from those encountered on the surface. Not only does the medium introduce a third dimension, which is not wholly analagous to that of the air since a definite limit is imposed on depth, but also a great many of the aids to surface navigation are either restricted in their use underwater, or are wholly inappropriate and will not function. The use of the principal aids to submarine navigation is briefly described in this paper, future developments being mentioned where possible. A more detailed examination is then made of the problems of underwater navigation, problems in the main that affect the accuracy of keeping a reliable dead reckoning. An account is also given of a gravity survey carried out in H.M. Submarine Talent, during which the author served as navigating officer. On this operation the requirement for position accuracy was high, and some of the methods used were of considerable interest. The survey also provided the opportunity for current and tidal-stream observations to be made at different depths and an account of these observations is given.

The plan. During the spring and summer of 1950 three small British yachts sailed 15,000 miles in the open Atlantic, the object being to compete in the Bermuda race and then to race back across the Atlantic to Plymouth. Two of the craft, Cohoe and Samuel Pepys, were of under 5 tons displacement and the third, Mokoia, was very little bigger.

The following method of drawing a position line from a celestial observation is suggested as a possible means of simplifying a small portion of the navigator's work. It avoids the use of azimuths, thereby simplifying chart work.

The method is based on a geometrical construction whereby the position line is determined from intercepts relating to two separate adjacent Assumed Positions; this construction may prove simpler than the present orthodox method, particularly as it does not involve the measurement of angles.