When there is relative movement between an observer and a wave source the observed frequency changes by an amount depending on the relative velocity. This is the doppler effect, and it has been realized for a number of years that it might be the means of measuring the speed of an aircraft over the ground, using radio waves transmitted obliquely and received again at the aircraft after being scattered at the surface of the Earth. By 1937 radio techniques had developed so far that letters patent were granted for systems which then appeared to be practical. A number of severe problems remained, however, and not until the close of the war did development programmes to resolve these problems make headway. Since that time equipments have been successfully produced, both here and in the United States of America, and sufficient operational experience has been gained for the value of the process as an aid to navigation to be assessed.

This paper describes a precision position and time service which could support the increased air traffic of the future, with an example of its application to air traffic control. Horizontal position and epoch time distribution are provided by Loran-C and vertical position by digital barometric altimetry. The proposed use of these systems for horizontal navigation, vertical positioning and landing approach is based on their successful use by current high-speed aircraft. The paper was presented at the 19th Technical Conference of I.A.T.A., Dublin, October 1972.

Civil Marine Radar (CMR) is now a mature instrument of some 50 years steady development. Following a short history, more to provide benchmarks of achievement than to satisfy historians, this paper examines what will drive the future development of CMR. The answer may not follow recent developments, but may well be the result of a fresh maritime modus operandi to fulfil the navigation, collision avoidance and safe passage needs of all types of craft operating in all types of water with different pressures and Operational Requirements (ORS). Having postulated fresh ORS, suggestions are made on how best to fulfil them in a logical and cost-effective manner.

Although the economic theory of congestion as applied to road traffic has been known since at least the time of Pigou its application to marine problems has been much slower. It is the purpose of this paper to remedy this somewhat by interpreting the theory in a marine context and to suggest some of the practical implications of taking proper account of congestion effects.

This, and the following three papers, were first presented at GNSS 2000, the Third European Symposium on Global Navigation Satellite Systems held in Edinburgh, Scotland from 1st to 4th May 2000.

GNSS, or more specifically, Satellite Based Augmentation System (SBAS), guidance provides the prospect of a low-cost means for aircraft to become equipped to fly area navigation (RNAV) operations. The implementation of such RNAV operations within UK airspace offers potential benefits to both the airline operators and the Air Traffic Service Providers (ATSPs).

Recent work on marine traffic engineering in Japan was reviewed in four papers published in this Journal in 1971. In the present paper, which may be regarded as a sequel to these, Professor Makishima offers some theoretical comments.

Many vessels trading on North Atlantic routes are equipped with weather facsimile receiving devices of various types. Ship-masters engaged on regular voyages in this area are thus able to conduct their own passage planning using the information readily available from these intruments. The capital cost in relation to other ship operation costs is negligible; in US dollars (1983) it is likely to be of the order:

There would be no problem in planning a vessel's route across an ocean if it were possible to forecast with total accuracy the actual sea state existing for the duration of a voyage. Such an ideal circumstance does not yet exist and a method must thus be used which incorporates flexibility to modify a voyage plan as actual weather varies from the prognosis. This means that a subjective approach to storm avoidance may, on occasions, be preferable to the stringent demands of a least-time track. The obsession of routing agencies with the latter method may be one reason why weather routing has not achieved the success it perhaps deserves.

A ship may be damaged or delayed by the action of sea waves on her hull or structure. Hull form and ship dimensions are usually selected on the basis of calm-water performance, rather than for sustained sea-speed.

Traffic separation was first introduced on a voluntary basis in the Dover Strait in September 1967, just over fifteen years ago. Compliance with the IMO provisions relating to traffic separation schemes has been mandatory for all ships during the last five years and for some ships for as much as ten years. It may therefore be appropriate to assess the effectiveness of routing off North West Europe by comparing collision statistics for five-year periods since 1957.

The results given in the following tables apply only to collisions involving trading vessels of over 100 g.r.t. under way and not engaged in any special activities. Collisions in harbours, rivers and congested port approaches where special circumstances apply are not included. The figures quoted for the Dover Strait have been checked against the results obtained by the National Maritime Institute but are based on different criteria, and there may be some discrepancies.

The area covered is the coastal region from the south-western approaches to the Ushant TSS to the approaches to the Elbe including all parts of the English Channel and the Dover Strait, but not including waters off the East Coast of England which are well clear of the traffic separation schemes and deep-water routes.

The numbers of collisions are based almost entirely on Lloyd's Weekly Casualty Reports. Information relating to encounter situations is based on voyage data supplemented wherever possible by information received from additional sources relating to the actual courses steered by each vessel. It is not claimed that the figures constitute a precise record but they should provide a good indication of changes in the incidence of collision off North West Europe.

Although the Astrograph has never been formally described in print, the basic principles of the instrument are sufficiently well known to require no further elaboration; so also are its limitations. Over many years, numerous proposals (but mainly unpublished) have been made for the extension of the Astrograph to cater for the Sun, Moon, and planets, as well as for a larger number of stars, but none have been really satisfactory. Without such improvements the Astrograph must have a very limited use, and accordingly a further study was made some time ago of its application to the Sun, Moon, and planets. Methods were developed on familiar lines for shifting (and rotating) the star curves for a standard declination to cater for neighbouring declinations, but these introduced complexities that were clearly unacceptable.

Radio approval for spectrum management, and vehicle EMC type approval for road safety, are different approvals for different purposes. Modern vehicle applications of radio systems for telematics purposes have resulted in both of these approvals having to be applied to radio systems fitted to vehicles. This paper looks at automotive EMC legislation and its interpretations relating to radio issues. The changes to radio type approval with the implementation of directive 1999/5/EC and the interpretations for automotive systems are discussed.

Recent advances in technology have encouraged proposals for new approaches to ATC in Europe and elsewhere. Two such proposals, both rather loosely framed, are for ‘free flight’ or for ‘seamless contracts’; otherwise ‘tubes of flight’. These concepts, and variations on them, aim to increase the traffic capacity of the airspace. They have been the subject of numerous published papers. Given the declared objects of these systems, it is surprising that, nearly without exception, these papers discuss the proposals only in qualitative terms. The present paper discusses idealised versions of these systems on the basis of quantitative studies. It is concluded that the ‘seamless contract’ is very probably unworkable in Europe. ‘free flight’ is workable in principle, but there is a need for investigation of possible mechanisms by which last-minute problems may be resolved.

Real Admiral Ritchie, who retired on 1 September 1982 after ten years as President of the Directing Committee of the International Hydrographic Bureau in Monaco, here looks at the work of the International Hydrographic Organisation, more particularly in those areas which are of direct interest to the navigator.

In 1919 an International Hydrographic Conference was called in London at which representatives from the hydrographic services of twenty-four nations attended. After discussing at length cooperation in the fields of charting, Notices to Mariners, and the international exchange of hydrographic data, it was resolved to set up a permanent Bureau. The Conclusion to the Conference reads as follows:

The International Hydrographic Bureau whose formation is here suggested fulfils, in our opinion, an imperative need. Assuring a close and permanent association between the National Hydrographic Services, it allows of the cooperation of the efforts of all maritime Powers to furnish navigators with more perfect and up-to-date nautical documents. Without limiting in any way the liberty and initiative which should be retained by the Offices of the countries concerned, the new organisation will avoid unnecessary effort and wasteful expenditure; it will create amongst the surveyors of the different countries a fruitful rivalry and personal relations which are frequently of great value. We are convinced that its rôle will constantly increase in the future, and that its establishment will tend greatly to advance the Science of Hydrography.

The italics in the above statement are mine. These words still reflect the most important aim of the International Hydrographic Organisation over sixty years later.

We recognize that in the general line of trade (or, as we have had underlined again recently, of war) there will be places where ships have to go but where, with the best will in the world, we have not been able to provide adequate charting or even to recommend anyone else's chart as fit for use. The master and his owners, or the naval commanding officer and his operational authorities, have got to weigh the advantages of calling at that port, or using that route, against the danger to the ship and decide whether the gain justifies the risk.

In 1973 we were astonished to hear that a foreign coaster on passage from a Bristol Channel port to Penzance had attempted to go between Godrevy Point, the north-eastern head of St Ives Bay, and Godrevy Island, some 2½ cables offshore, at low water. Fortunately for her, she was spotted by the local coastguard before she was irrevocably committed to the passage – and dissuaded. The largest scale chart of the area, Chart 1168, is on a scale of 1: 25000, and shows the passage as some ¾ inch across from high waterline, or less than half an inch between drying rock shelves. Admittedly it did show a narrow gap where the contour lines suggested that more than 5 m of water could be carried through the centre of the passage. The sailing directions state that the channel outside the island, between it and the outer shoals, should not be used without local knowledge. The inner passage is briefly mentioned but no instructions for passing through it are given.

We present a method of teaching the basics of celestial navigation, using the Javascript programming interface to Google Maps. This offers the teacher of celestial navigation many highly visual and flexible investigative and presentation options, all using the familiar Google Map system. In this paper, we discuss the programming route to Google Maps, and demonstrate an exercise of correcting the assumed position of a hypothetical lost ship, using sights of the Sun, suitable for classroom use. We also present an analysis of the relationship between the proximity of the assumed to the actual position of the ship, and the outcome of a sight-reduction procedure.

At depths of, generally, between 20 and 250 fathoms in the oceans, sonic and ultrasonic transmissions are frequently scattered by a layer which can be detected on the echo sounding trace, sometimes so strongly as to suggest a sea-bed echo. The cause of this layer, of which the depth has been observed to rise at sunset and sink at sunrise, is not precisely known, though it is generally thought to be biological. Investigations into the deep scattering layer (DSL), as it is called, are being conducted in many countries, principally in the United States, France and Great Britain, and a recent paper by Tchernia has set out the present state of knowledge on the subject.

This paper is a report on some early findings of a long-term study which has the ambitious objective of suggesting better alternative solutions to the general problem of controlling a collection of aircraft. The study aims to answer questions about the optimum division of responsibility between the aircrew and ground A.T.C., about the way in which the A.T.C. tasks are shared between a number of controllers and A.T.C. computers, and about the fundamental principles on which traffic flow is organized.

This paper describes a number of proposals concerning the correction of the errors of magnetic compasses. The first proposal concerns the correction, by means of special soft iron correctors, of the deviating effects of both vertically and horizontally induced magnetization.

A scheme for removing constant error without having to use algebraic addition or even having to record the existing deviations is next described.

A scheme is then suggested whereby, provided no constant deviation is present, a compass may be corrected for the effects of permanent magnetism in four operations, each of which consists of the complete removal of deviation on a particular heading by a particular corrector.

Possibilities of putting compasses below decks without seriously affecting their performance are also discussed; these particular suggestions cannot apply to merchant ships in which magnetic cargo is being transported. Suggestions are also made of correcting the compass by modifying the disposition of the magnetic material in the bridge structure instead of by adding a corrector to the compass binnacle.

Finally, a scheme is introduced to maintain an aeroplane compass mounting parallel to the surface of the Earth during a level turn by using the centrifugal force due to the turn.

This paper puts forward five separate suggestions concerned with the correction and siting of magnetic compasses. The suggestions are unrelated to each other except in the fact that they have all resulted from viewing the problems from a deliberately unconventional standpoint. Some of the solutions proposed may be of interest to those concerned with magnetic compasses in ships, aircraft and vehicles.

When geophysical measurements are made from the air, it is important to know the position of the aircraft. The position at any time is usually known from a combination of position-fixing and dead-reckoning systems. In-flight optimization of this combination is a well-studied subject. When post-flight track plotting is required for geophysical survey, use can be made of both the initial and terminal position fixes to correct the dead-reckoning track and hence improve on the in-flight version. This technique is applied to compute the track of aircraft conducting ice thickness measurements in the Antarctic, and the effect of certain errors is evaluated. The algebraic results are equally applicable in parts of the world where better navigational aids are available. A relation is derived between the track plotting errors and die errors in the geophysical measurement such that the precision of one is not degraded by errors in the other.

Upper winds over the North Atlantic are strong and their circulation is complex; until aircraft speeds are considerably increased, therefore, the choice of a route which will take the maximum advantage of the wind distribution consistent with safety can make a worthwhile contribution to operating economy. This paper describes some of the methods adopted by Trans-Canada Airline on its North Atlantic route to achieve this end.

Vehicle navigation systems use various sensors and the global positioning system (GPS) to locate a vehicle. This location is then matched to a map database to provide navigation information. Between GPS updates, the vehicle's heading angle and forward speed are used to “dead reckon” its position. Heading angle is often measured by integrating the output of a rate gyroscope. For this measurement to be equal to the vehicle's heading angle, the vehicle should not experience any rotation about its roll or pitch axes. For an automobile, the roll and pitch angles are small and may be neglected for the purposes of navigation. This article demonstrates that this same assumption is not true for a motorcycle. Through simulation, it is shown that for a motorcycle, obtaining a meaningful heading angle from a single angular rate measurement requires accounting for the motorcycle's roll angle. Methods to estimate roll angle and heading angle from available navigation measurements are presented, and two possible sensor configurations are compared. A motorcycle navigation scheme based on these roll angle estimation methods is shown to produce exceptional results in a simulation environment.