In 1960 Hanssen and James described to the Institute a system developed and used by the United States Hydrographic Office for selecting the optimum track for transoceanic crossings by applying long-range predictions of winds, waves and currents to a knowledge of how the routed vessel reacts to these variables. The paper (Journal, 13, 253) described how, over a period of two years, an average reduction in travel time of 14 hours was achieved over 1000 optimum routes.

In the present papers, presented at an Institute meeting held in London on 19 April, Captain Wepster of the Holland-America Line first of all goes into the benefits which effective ship routing offers the ship operator and then describes the results of the experimental routing programme undertaken by his Company in association with the Royal Netherlands Meteorological Institute. Mr. Verploegh of that Institute then discusses the programme from the forecaster's point of view.

The earlier experiments in the weather routing of ships, which in the middle fifties were carried out in the United States of America, have shown that in some instances the combined use of wave-condition charts and extended weather forecasts enabled a ship to follow a more direct route across the ocean without encountering the hazard of a severe storm and a great loss of time, which the shipmaster would have tried to avoid by taking a more southern and generally much longer route.

The theory of the problem of collision at sea has been formulated by many authors and the results of the theory have been used, notably by Morell, Hollingdale and Calvert, to establish practical manoeuvring rules to avoid collision. Any treatment which attempts to take into account the uncertainties in the information available to the navigator is bound to be technically difficult. It is arguable that a theory in which no account has been paid to the possibility of equipment errors is incomplete.

In the discussion on the theory and practice of collision avoidance, two areas have been particularly liable to dispute, namely the rules for direction of manoeuvre and for responsibility for manoeuvre. Where two craft meet, some propose a rule of manoeuvre direction fixed by relative bearing, others a flexible rule designed to increase initial miss distance. Some think both craft should manoeuvre (dual responsibility), others only one (single responsibility).

Aircraft navigation using doppler and orbital information transmitted from a satellite is shown to be feasible, at least in a limited sense, using the least squares, differential correction method of computation. If sufficiently accurate velocity information can be provided, this approach could yield positions for long-range aircraft that are an order of magnitude more accurate than have been achieved with other world-wide, all-weather, all-altitude systems, such as doppler and inertial navigators.

The least squares, differential corrections solutions for both position and velocity do not converge for reasonable initial errors. Therefore, accurate aircraft velocity components, such as those provided by a doppler navigator, must be known. For one-knot velocity errors the position of a 500-knot aircraft can be determined to one-half nautical mile or better for latitudes up to 70 degrees. Several-knot velocity uncertainties result in position errors of a few nautical miles.

The position accuracies for supersonic aircraft are limited by the velocity accuracies achievable with the best doppler navigators. Computational methods that yield velocity as well as position, so that the satellite system would not have to depend so much on another navigation aid, would be most desirable.

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.

In 1518 a Spanish gentleman, just back from the West Indies, addressed a Summary of World Geography to his King. In the Dedication he pointed out that since the Pope's Line, which parted the Portuguese and Spanish spheres, ran through the mouth of the River Amazon, 28°W. of Ferro, all the World beyond 150°E. (i.e. 130°E. of Greenwich) lay open to exploitation by Spain. And according to the World Map of the day the area included Java, Japan, King Solomon's Ophir, and (best of all) the Spice Islands or Moluccas from which the Portuguese were already making fabulous fortunes. This gentleman was not the only person to speak to the young King on this matter. The captains and pilots who had opened up the Spice Islands for Portugal were dissatisfied with the rewards which their own King had given them, and a number of them offered their services and their special and secret knowledge to his rival. Ferdinand Magellan was one of them. From his experience in the Far East he was of the opinion that the Moluccas could be safely approached from the west, by way of the Great Ocean. And it should be emphasized that in suggesting this he had no romantic notions about becoming the first man to circumnavigate the globe. He put forward a business pro position which the Spanish King accepted. Immediately the most thorough preparations were set on foot. They included the making of new charts, new globes, new sea-quadrants and sea-astrolabes, by the best pilots and craftsmen of the day, of whom the most were Portuguese.

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’.

The previous paper described how the two components of a compound system could be combined, through the medium of a pictorial display, in a common coordinate system. This essential process can be carried out by an airborne digital computer with considerable advantage, and with a degree of refinement—e.g. data smoothing— which would be beyond the scope of the simpler manually-operated system. In other words, the computer can introduce a second mode of compound operation which differs from the simple relationship between position-fixing and D.R. systems described earlier, in that by continuously combining the incoming information from the position-fixing system and the dead-reckoning device it can deliver an output of a substantially higher quality than that of either input taken separately.

In the days of sail a merchantman's success as a trader was governed by the seamanship of her master and the sailing qualities of the ship. A vessel which could turn easily to windward in difficult conditions could sometimes manœuvre under sail, in and out of port, without assistance while her more ungainly sister was dependent upon warping, kedging and towage by craft under oars. More important still, when on passage the efficient sailing ship could get herself out of trouble if she found herself in a tight corner on a lee shore in a gale of wind.

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.