The paper discusses the way in which the accuracy provided by different navigation systems can best be presented diagrammatically, and it is concluded that contours of constant 95% radial error give the best general picture of a system. Where a more detailed picture is required error ellipses can be added at suitable points in the system. The 95% radial error of fixing is calculated for radial, rθ, azimuthal and different hyperbolic systems, and graphical methods are developed for drawing contours along which the 95% error is constant, and also for drawing 95% ellipses. Diagrams show typical results for the different systems.

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.

This paper was presented at a meeting of the Institute in London on 21 January 1981 with W. H. McKinlay in the Chair. The views expressed do not necessarily represent CAA policy, but Mr Attwooll discusses the derivation of fuel-uplift requirements from considerations of safety and regularity of the flight, using additional information on the probability of various adverse contingencies such as headwind or ATC delay. Methods of safely reducing fuel reserve requirements are discussed, including improvements in navigation and the on-board decision-making process.

Airport visual aids are examined for failure of transfer from chromatic (i.e. normal) to achromatic viewing situations which would suggest a non-redundant use of colour, and for their information value during VFR (visual flight rule) operations as a function of the airport operating classification for which they were designed. From photographs taken under visual meteorological conditions at night, slide sequences representing the visual presentations associated with aircraft movements during taxi-out, take-off, approach and landing operations were prepared and shown to experienced pilots in a time-stressed forced-choice procedure. The results suggest that among displays in current use only the signal light from the control tower is completely colour-dependent. Also, the information value of some taxi-way and approach lighting components might be questioned. An argument is presented for a ‘building-blocks’ review of the airport visual-aids system that could in some cases result in improved relationships between economy of display content and information value.

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.

The author, a Master Mariner and Section Chief of the All-Union Research Institute of Marine Fisheries and Oceanography, Moscow, U.S.S.R., deals with the principle of clockwise rotation of the line of relative motion, as applied to simultaneous encounters with several ships. He presents arguments for a strict compliance with the well known dictum of Captain Oudet: ‘Encounters at sea are governed in such a way that each party knows what he should do and what the other should do.’ The paper was written in collaboration with the late Captain G. Shoomayko.

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.

The high concentration of aircraft near aerodromes, with consequent collision risk is well known. It is at present necessary, in poor visibility, to guarantee the indispensable commodity of safety by the sacrifice of schedule regularity and fuel economy. So long as this is the case, the problem of terminal navigation and control must be regarded as one still demanding a satisfactory solution.

In a recent paper on shipborne radar the authors tried to analyze the mental approach of a master or pilot to the problem of handling his ship in a confined space when berthing in fog. The sense of loss that is caused by the absence of direct vision was referred to and various means by which confidence and control might be restored in these circumstances were considered. In that paper only the inadequacies of present-day shipborne radar in meeting these requirements were discussed. The approach to the problem can, however, be broadened to include the whole question of port operation in fog, and the present paper attempts to describe the general requirements and to consider in particular the role of shore-based radar and the manner in which the information obtained from radar or other aids should be presented to the master.

The lane-level map, which contains the lane-level information severely lacking in widely used commercial navigation maps, has become an essential data source for autonomous driving systems. The linking relations between lane-level map and commercial navigation map can facilitate an autonomous driving system mapping information between different applications using different maps. In this paper, an approach is proposed to build the linking relations automatically. The different topology networks are first reconstructed into similar structures. Then, to build the linking relations automatically, the adaptive multi-filter algorithm and forward path exploring algorithm are proposed to detect corresponding junctions and paths, respectively. The approach is validated by two real data sets of more than 150 km of roads, mainly highway. The linking relations for nearly 94% of the total road length have been built successfully.

The integration of magnetometers and Inertial Navigation Systems (INS) is widely used in low-cost navigation systems. However, even if the system has been calibrated, random magnetic disturbances still appear in practical applications, which lead to large heading errors. To solve this problem, an adaptive anti-disturbance method to overcome random magnetic disturbance is proposed. First, disturbances are classified and analysed in detail based on actual road vehicle driving data. Then an Adaptive Robust Extend Kalman Filter (AREKF) is designed to resist sudden disturbances. However, an AREKF may accumulate errors slowly when a long-term disturbance exists. Considering this situation, this paper proposes that AREKF is used to maintain accuracy in the early stages, at the same time as the magnetometer is quickly calibrated with a Kalman filter. Then, the new magnetometer parameters are put into the AREKF to suppress long-term disturbances. Finally, cascading these two modules, not only the sudden disturbance can be overcome, but the situation of long-term disturbances can be suppressed. The results of simulation and an actual driving test show that the proposed method can effectively overcome random magnetic disturbances in both the short and long term.

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.

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.

An approximation procedure is described, which greatly simplifies dead reckoning on a tortuous path. The journey is divided into N segments of equal length, L. The overall direction is approximately the average direction of the segments. The net distance is approximately NL[1-var(α)/2], where var(α) is the variance (in radians squared) of bearings, αi, corresponding to the segments, and must be less than 0·7. Propagation of random errors is discussed. In a case study in sub-tropical rainforest the technique gives an estimated position whose associated circle of 68% confidence has a radius of about 10% of the net distance.

Marine radiobeacons have been used to broadcast differential corrections for global navigation satellite systems (DGNSS) for nearly a decade. The method has become the accepted international standard for maritime applications. The background to the development of the system is described and the current status of radiobeacon DGNSS services around the world reported. The applications are discussed, including the function of radiobeacon DGNSS as the position sensor within integrated systems, together with the performance requirements imposed by associated systems such as ECDIS and Automatic Identification Systems. The advantages and disadvantages of the radiobeacon system in regulatory, administrative and technical terms are discussed and the potential for development of the system is considered. The future role of radiobeacon DGNSS in the overall mix of systems is assessed taking into account the introduction of geo-stationary overlays, and possibly Loran-C, for provision of DGNSS corrections.

The hydrodynamic interaction effects on a tug operating in close proximity to a larger vessel can result in dangerous situations for the tug. To date most studies have focussed on the interaction effects between the vessels when they are operating in parallel, which represent only one of many practical ship-assist manoeuvres. It is therefore necessary to investigate a wide range of tug-ship combinations to obtain a detailed understanding of these effects. This paper discusses the hydrodynamic interaction effects on a tug operating at various relative positions and drift angles to a larger ship, both moving together at the same forward speed. The hydrodynamic effects were determined using Computational Fluid Dynamics (CFD) simulations that were validated using captive model test data. The range of manoeuvres discussed in this paper provides a comprehensive overview of the hydrodynamic interaction effects on a tug enabling tug operators to identify safe operating envelopes for their vessels.

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.

Four manuscript charts of British ports, and notes on them, were made in the 1590s by an English Catholic pilot, N. Lambert. They were sent to Don Juan de Idiáquez, Philip II's secretary, through the mediation of an English Jesuit exile, Robert Persons (or Parsons). Lambert also offered to pilot Spanish ships and guide Spanish troops in raids on the coasts of England and Wales, and prepared a list of appropriate targets. Being some of the earliest charts of the ports concerned, and hitherto unpublished, they are here presented with relevant background material.

The increase in the number of commercial flights highlights the need for air traffic to follow air procedures. Unfortunately, general aviation aircraft used for recreational purposes keep entering controlled and restricted airspace without obtaining permission from air traffic services. Given the safety and operational problems this could potentially cause, this paper examines the underlying reasons for these incidents occurring. In particular, it analyses airspace infringements between 2008 and 2017 involving general aviation flights that were recorded in airspace in which a large number of commercial flights also fly in Europe and America. The reports were analysed based on an initial assessment of their quality. Information was latent in the narrative and subsequently both qualitative (content analysis) and quantitative methods (descriptive statistics) of analysis were used. The analysis revealed that airspace infringements were related to the pilot's flight planning, that is, flight-route choice, navigation skills and communication, in addition to requirement to adhere to airspace procedure. The findings could be used by national authorities and flying clubs to promote safe flying in these regions.

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.