The year 1932 was one which had no great apparent significance for navigators, and yet it saw the commencement of two new lines of research which today, after an interval of more than a quarter-of-a-century, promise important contributions to the safety of navigators both at sea and in the air.

The two lines of research were superficially quite unrelated, but fundamentally they relied upon the same principle—the detection of radiant energy emitted by objects solely as a result of their temperature. The first of these small beginnings was the discovery by K. G. Jansky that radio waves could be detected from extra-terrestrial sources: the second was the commencement by the U.S. Signal Corps Engineering Laboratories of an intensive study of infra-red devices with the object of obtaining night vision without illumination of the field of view.

From Jansky's discovery has sprung the whole science of radio astronomy, which has revolutionized our ideas about the universe, and brought in its wake, as one practical benefit, the radio sextant. From the work of the U.S. Signal Corps there resulted a number of very useful infra-red components, including the pneumatic detector, better known as the Golay cell.

One of the essentials of the Collision Regulations is that they should, so far as possible, eliminate doubt in the minds of navigators using them. In recent years, an amendment has introduced a serious, dangerous doubt.

Early in 1967, a few months before the restored Meridian Building of the Old Royal Observatory was opened to the public by Sir Richard Woolley, the Astronomer Royal, I received a visitor in my office then in the Meridian Building — later, I was to move to the west summer house of Flamsteed House. My visitor was Colonel Humphrey Quill, Royal Marines, Master of the Worshipful Company of Clockmakers that same year and author of the hook John Harrison, the Man who Found Longitude, which has become a standard work. He brought with him some manuscripts written by the subject of this lecture — Nevil Maskelyne, fifth Astronomer Royal, who lived in Flamsteed House for 46 years from 1765, making most of his important astronomical observations in the very building in which Col. Quill and I were sitting.

Map matching is an important algorithm for any location-based service, especially in navigation and tracking systems and services. Identifying the relevant road segments accurately and efficiently, given positioning data, is the first and most important step in any map matching algorithm. This paper proposes a new approach to searching for road candidates by clustering and then searching road segments through a constructed hierarchical clustering tree, rather than using indexing techniques to query segments within a fixed search window. A binary tree is created based on the hierarchical clustering tree and adaptive searches are conducted to identify candidate road segments given GPS positions. The approach was validated using road maps with different scales and various scenarios in which moving vehicles were located. Both theoretical analysis and experimental results confirm that the proposed approach can efficiently find candidate road segments for map matching.

The following discussion took place at an open session of the Technical Committee held at the Royal Aeronautical Society in London on 19 January 1972 with Mr. H. E. Smith in the Chair.

The Chairman: Relative navigation has a wide connotation, but for the purpose of our discussion it may be applied firstly to aircraft management in the positive or passive sense, arising from an air-to-air navigational interrogation capability, and secondly to the means whereby this capability may be realized.

This paper is based on the results of the ‘GNSS Support Task’ study for the European Commission, DGXIII. It summarises the results of the cost benefit analysis in terms of coverage, accuracy and safety requirements for different types of user and describes the most cost-effective GNSS 2 architecture. These analyses also assume that the overall system is layered into wide area, regional and local systems. The future planning of satellite navigation is essentially driven by the wide area requirements and ensuring that these are global and seamless. There is some flexibility in coverage and accuracy for a wide area system in that it can be augmented regionally or locally if required, but it must provide the highest level of safety required. The paper approaches the architecture for a future navigation system from this safety aspect. An analysis of the chosen architecture shows that the required safety performance can be met. An implementation plan is described which allows a gradual evolution from the first system to be realized for safety critical operations to a fully civilian owned and operated system.

The following discussion took place at an Ordinary Meeting of the Institute held in London on 15 February 1963.

Dr. Ramsayer's paper, presented at the tripartite meeting on automatic navigation held in Paris last April, describes a dead-reckoning computer on which position is presented instantaneously on a map.

The so called Automatische Koppelkarte has been developed by the Institute of Air Navigation of the Technical University of Stuttgart, and is a new type of dead reckoning computer differing from the usual navigation computers in that position is immediately indicated on a map; there are many possibilities for combining the device with other navigational aids.

Fig. 1 shows a schematic diagram of the computer. It consists of the computer, the map display and the course and track indicator. The station selector and the coordinate transformer shown in Fig. 1 are additional units, only used when monitoring by tacan is desired, as will be described. The computer is fed by a gyro-magnetic compass and a true airspeed transmitter. The wind is set at the map display, and ‘grivation’ at the course and track indicator. From these data both the flight path and the track are computed. The flight path is resolved in two rectangular components and is displayed by a light pointer on a map of conformal conical projection. The standard parallels of the map are selected in such a way that the distortion in length is practically negligible for the area of interest.

To find out the origins of the nautical mile it is necessary to go back to early times, for, like so many other things, it did not spring up in full bloom in a day, but evolved by slow degrees.

Early man, seeking units of measurement, logically looked about him for something in nature that he might use as a standard. For very short distances he used the width of his finger, the width of his hand, his span, the length of his foot, or the length of his forearm. As these varied between men, so the length of the derived units varied. The foot, for instance, varied from 11 to 14 inches. Even greater variation occurred in the length of the cubit, which originally was taken as the length of the forearm, from the elbow to the end of the middle finger. This unit was widely used, but varied from country to country, and was not even constant within various parts of the same country in some instances.

A realistic runway capacity study for two major airports, namely Frankfurt (EDDF) and Chicago O'Hare (ORD) is presented, assessing the effect of optimal scheduling on the runway capacity and air traffic delays. The maximum position shift (MPS) runway scheduling algorithm, used in the study, was developed by Trivizas at the Massachusetts Institute of Technology (1987).

EDDF is studied in the context of 160 major European airports, with a real traffic sample from 6 July, 1990. ORD is studied in the context of 26 major US airports using a large traffic sample from 1 March, 1989. Secondary airport traffic has been assigned to the geographically nearest major hub and time compression has been used to extrapolate to an artificially denser scenario.

The results show that optimal scheduling can bring about capacity improvements of the order of 20 percent, which in turn reduce delays up to 70 percent. These results are the product of a dynamic traffic management process which has been visually validated by observing animated runway operations and monitor functions.

The study has been conducted with TMSIM, a comprehensive, object-oriented simulation tool that allows one to build an understanding of the structure and functionality of the air traffic control system, by modelling its components, their functionality and interactions, and measuring component and system performance. It features interactive route network editing (using menu/mouse techniques), complete route and airport structure modelling, independent flight and ATC objects, 3-D animation, advanced algorithms for scheduling, routeing, flow management, airspace restructuring (sectorization) and performance (capacity and communications workload) analysis.

This paper was presented at an RIN meeting on ‘Air and Marine Radar Developments’ on Wednesday 16 January 1991.

During the last decade there have been significant developments in the civil marine radar field, resulting in: (1) Improved radar detection performance; (2) Improved operational facilities; (3) Improved reliability; (4) High brightness, daylight viewing, colour and monochrome displays with full ARPA performance; (5) Integrated radar and navigation systems; (6) Reduction in costs.

Marine casualties usually arise through a combination of complex conditions. To trace any one of the conditions involved, and its reaction on others, not only helps to reveal the cause of an accident but is also important in understanding the nature of such casualties.

Like accidents on land, marine casualties do not arise spontaneously but have ascertainable causes, rarely a single cause but rather a combination of causes. Thus in a collision in fog in a narrow channel we must consider not only faults in carrying out a manœuvre but also the natural phenomena of fog and the narrowness of the channel.

This, and the following three papers were presented at the Royal Institute of Navigation meeting ‘Management of Air Traffic Flow in Europe' on 15 November 1989.

One of the growth industries in Europe is the production of articles in newspapers and programmes on radio and television which deal with European air traffic control. They usually have titles like, ‘The Crisis in ATC’, or ‘European Air Traffic Meltdown’. Jane's Airport Review, in October 1989, had an article entitled ‘Wanted: One ATC System for Europe’.

Omega is one of a wide range of navigational aids that have been developed and are in everyday use by ships and aircraft. By contrast, outside the military field as yet there has been no significant application of these aids to mobile land vehicles. The reason has been a mismatch between the perceived accuracy requirements of the potential user, what he is prepared to pay, and what technology could provide.

Anchor work is generally considered to be a question of seamanship rather than navigation; Commander Sharpey-Schafer's paper, which deals with a number of subjects only indirectly allied to navigation, is, however, presented here because what he has written will be of interest to so many navigators.

Multicollinearity and its effect on parameter estimators such as the Kalman filter is analysed using the navigation application as a special example. All position-fix navigation systems suffer loss of accuracy when their navigation landmarks are nearly collinear. Nearly collinear measurement geometry is termed the geometric dilution of position (GDOP). Its presence causes the errors of the position estimates to be highly inflated. In 1970 Hoerl and Kennard developed ridge regression to combat near collinearity when it arises in the predictor matrix of a linear regression model. Since GDOP is mathematically equivalent to a nearly collinear predictor matrix, Kelly suggested using ridge regression techniques in navigation signal processors to reduce the effects of GDOP. The original programme intended to use ridge regression not only to reduce variance inflation but also to reduce bias inflation. Reducing bias inflation is an extension of Hoerl's ridge concept by Kelly. Preliminary results show that ridge regression will reduce the effects of variance inflation caused by GDOP. However, recent results (Kelly) conclude it will not reduce bias inflation as it arises in the navigation problem, GDOP is not a mismatched estimator/model problem. Even with an estimator matched to the model, GDOP may inflate the MSE of the ordinary Kalman filter while the ridge recursive filter chooses a suitable biased estimator that will reduce the MSE. The main goal is obtaining a smaller MSE for the estimator, rather than minimizing the residual sum of squares. This is a different operation than tuning the Kalman filter's dynamic process noise covariance Q, in order to compensate for unmodelled errors. Although ridge regression has not yielded a satisfactory solution to the general GDOP problem, it has provided insight into exactly what causes multicollinearity in navigation signal processors such as the Kalman filter and under what conditions an estimator's performance can be improved.

Dr. Freiesleben, an Honorary Member of this Institute, discusses the geometry of ellipses and hyperbolae on the sphere. These are the curves which correspond to position lines based on the constant sum or difference of distances from two fixed points. Originally applied to astronomical position lines they now have a wider application to electronic fixing systems of global coverage like Omega.

One of the problems in arctic navigation by astro is the twilight period. At this time, if the Moon is below the horizon, suitable objects for sextant observation are not easy to find. The difficulty is aggravated by the fact that on certain flight paths the arctic twilight may last for many hours. It must also be remembered that in these areas the behaviour of the magnetic compass and of radio aids are often unreliable and this increases the relative importance of astro-navigation. With the introduction of the periscopic sextant into air navigation it has become possible to pre-set the instrument for a given star or planet and satisfactory observations may be possible when the heavenly body is still below the level of casual perception for the unaided eye. In this connection it is necessary to know what stars are likely to be seen under twilight conditions if efficient flight-planning is to be carried out.

During the Antarctic summer season of 1949 the Norwegian sealer Norsel, which had been chartered by the expedition, landed the Norwegian-British-Swedish Antarctic Expedition in Queen Maud Land in the Antarctic. In January 1951 the ship took down relief personnel and stores and for this trip the Admiralty, at the invitation of the planning committee, appointed the author as an observer. The decision to appoint a member of the navigation branch was made partly so that the techniques of ship handling and navigation in ice could be studied; and since the captain of Norsel, Captain Jakobsen, was extremely experienced in every aspect of ice navigation, a great deal of valuable information was acquired. The Institute had also suggested a number of astronomical observations that might usefully be made in polar areas and the Admiralty gave its approval for the observer to make them.

The fact that the de Havilland Comet cruises at nearly double the flying speed and nearly double the flight altitude of comparable piston-engined airliners is a measure of the great leap forward in air transport which the introduction of gas-turbine engines has brought about. It also illustrates an inherent feature of jet aircraft, for only at high speed and high altitude do turbo-jet engines, and to a less critical extent turbo-prop engines, operate at their maximum efficiency, expressed in distance flown per gallon of fuel consumed. With reduction of altitude and speed, however, the fuel consumption does not fall off proportionately and efficiency decreases rapidly. For example, even when taxying on the ground the Comet's fuel consumption is about 70 per cent of that at cruising altitude, and when flying at sea level the still-air distance flown on a given quantity of fuel is less than half of that at cruising altitude. In other words you get the best out of a jet aircraft when you are going somewhere fast, and when the length of the flight is sufficient for the aircraft to climb to its optimum cruising altitude and remain there for a considerable proportion of the flight time.