This paper deals with the facilities for landlall that can be provided by lighted aids to navigation. The relationship between the navigational errors of ships approaching from the open sea and the performance to be selected for a landfall light is worked out. The probabilities of a successful landfall in various circumstances are then analysed. Finally the limitations of light as the sole aid to navigation in the process of making a landfall are discussed. Rear Admiral van Hooff was for long head of the Netherlands Pilotage and Lighthouse Service; Ir. Sirks is technical director of the Netherlands Lighthouse Service.

The US Coast Guard has a project to provide a differential global positioning system service for harbour and harbour approach (HHA) areas of the coastal United States. The Great Lakes, Puerto Rico and most of Alaska and Hawaii will also be covered by the service. The Coast Guard's DGPS system will fulfil the 8–20 metre navigation accuracy requirement for HHA with an availability of up to 999 percent. The Coast Guard intends to provide this service to the general public and other government agencies, as well as use the system for its own missions. This capability is expected to enhance maritime safety in keeping with the National Transportation Policy by providing an all-weather radionavigation service to supplement existing radar and visual techniques, as well as a highly accurate position sensor for future electronic chart displays. This paper describes the Coast Guard's programme. Background and historical information on the development of pseudorange differential GPS is presented first, followed by a description of currently available technology. Various aspects of the Coast Guard's plan for implementing DGPS are then described, concluding with a rough project time line and a statement concerning Federal DGPS policy.

This paper examines the problem of those ship collisions which are associated with infringements of the International Regulations for Preventing Collisions at Sea. Experimental evidence indicates that there are classes of encounters which lead to indecision and uncertainty on the part of ship's officers. It is suggested that the identification of these classes of encounters is the first step towards eliminating the difficulties associated with them.

In order to more restrict the transverse orbit error, a new method named “differenced ranges between slave stations by transfer”, similar to Very Long Baseline Interferometry (VLBI) observation, has been developed in the Chinese Area Positioning System (CAPS). This method has the number of baselines added, the baseline length increased and the data volume enlarged. In this article, the principle of “differenced ranges between slave stations by transfer” has been described in detail, with the clock offset between slave stations and system error which affects the precision of the differenced ranges observation being discussed. Using this method, the differenced observation of the SINOSAT-1 satellite with C-band between slave stations from 6 to 13 June 2005 was conducted. Then a comparison was made between the accuracy of orbit determination and orbit prediction. A conclusion can be drawn that the combination of pseudo-range receiving the own-station-disseminated signal and the differenced range observation between slave-slave stations has a higher orbit determination and prediction accuracy than using only the former.

This study attempts to offer the first ever analysis of Austrian aviation cartography from its origins in 1908 to 1938. The thematic focus is on Austria's contribution to the debate on the standardisation of aeronautical charts on an international scale, on the continuities and changes characterising the aeronautical charts produced in Austria, and on a comparison of these maps with similar ones from other countries. The paper aims to expound on the thesis that, while the theoretical basis for aeronautical charts had principally been in place internationally and in Austria during the 1910s, there had been almost no practical follow-up on this know-how in Austria between 1915 and 1922. After 1923 novel aeronautical charts were produced, but the Austrian output sometimes fell below international standards regarding both quantity and, in part, also quality. The international agreed rules were interpreted in keeping with Austria's own requirements. It appears, however, that this development was not limited to Austria, as the new rules took hold in other countries somewhat belatedly as well.

When a ship is moored by a single anchor at the anchorage, its combined motions (i.e. yaw, sway, surge, etc.) are usually induced by external forces. Previous studies have gained some insights into the forces on anchor chains, but the motions for Capesize vessels still need to be further investigated. The length of anchor chain required for safe anchoring also needs to be carefully calculated rather than determined solely by the experience and judgement of Captains. The relationship between the length of chain and water depth, wind force, current velocity and the trim (draught difference forward/aft) requires further study. Our new methods consider all necessary factors which may exert significant influence on ships, including not only the water depth at the anchoring location but also the particulars of the ships, its equipment and the environmental conditions. Here, a numerical simulation model to describe the behaviour of an anchored Capesize ship is presented, with the comparison of results between simulations and real time model tests carried out. A discussion highlights the important features of the methods which provide mariners with theoretical solutions.

The January 2009 issue of the Journal of Navigation included a paper (John Wilde Crosbie 2009) entitled, “Revisiting the lessons of the early steering and sailing rules for an e-navigation age.” Following a description of the development of the COLREGS from the early 19th century, he concluded that the current steering and sailing rules should be replaced by a single rule more suited to modern conditions. This might take the form of a rule stating that a vessel taking action to avoid collision should not pass ahead of the other vessel. Such a rule would require a radical change in the philosophy of collision avoidance at sea, and evidence is required that it would be both effective and acceptable by mariners. Radar simulator experiments, conducted by the author some years ago in another context, suggest that this might be the case. An analysis of the experimental results and some conclusions are reported in this paper. The author recommends that further trials, specifically designed to test the Crosbie proposals, would be desirable.

The time dispersion effect affects the accuracy of solar time difference of arrival (TDOA) navigation. In this celestial autonomous navigation, Mars's moons are reflecting celestial bodies, and their shape affects the TDOA dispersion model. In the modelling process of traditional methods, the moons of Mars (Phobos and Deimos) are regarded as points, which causes the model to be inaccurate. In order to solve these problems, we simplified the Mars's moons into ellipsoids or solid diamonds, and then established a TDOA model with the nonspherical Mars's moons as reflecting celestial bodies through differential geometry and geometric optics. Finally, we analysed the time dispersion caused by the Mars's moons in theory. Theoretical analysis and experiments show that the point model error is 5·66 km, and the 3D model error is within 70 m. Thus, the 3D TDOA model established in this paper is meaningful. In addition, the Sun–Mars-moons–spacecraft angle, solar flare, three-axis length, and attitude of the Mars's moons have a great effect on the dispersion profile, while the Mars's moons-to-spacecraft distance has a small effect.

The flight instrument systems used in large modern transport aircraft represent a considerable development from the standard instrument panel in use at the beginning of this decade. Radio and navigational information is coordinated in a single display and flight direction is provided by means of a separate instrument in which it is normally composited with attitude information. The system contains sufficient redundant information to provide positive warning of a malfunction, and is normally used in conjunction with an automatic pilot which is capable of carrying out the approach accurately and reliably, monitoring control being exercised by the pilot by means of the flight system. Synthetic damping and automatic throttle control of airspeed may also be provided.

Statistics based on autopilots in current airline service suggest that an acceptable standard of safety for scheduled automatic landing is not attainable by single-channel autopilots. Adequate safety during the automatic landing manoeuvre can, however, be attained by a multiplex autopilot now under development. Provided that the necessary ground aids are installed, it appears feasible to introduce scheduled automatic landing by 1970.

Instances of merchant ships beset in times of ice pressure in the Gulf of St. Lawrence were investigated to study the observed relationship between winds and ice pressure generation. The relative power of the ships reported beset was calculated in an attempt to relate ice pressure severity with ship performance. Most pressure episodes occurred during onshore winds or near the time of major wind shifts. Ice pressure intensity during onshore winds appeared to be related to wind strength and duration and distance from shore. The ‘Mouth of the Gaspé Passage’ area was anomalous.

This paper was originally published in Vol. 34 of the Journal (p. 286). In its reprinted form, it has been reduced in length by Robin Payne. It is followed by comments from Stuart Quarrie.

Captain Illingworth's paper was read to an Ordinary Meeting of the Institute held at the Royal Geographical Society on 17 March 1950. Introducing the speaker, the chairman, Captain G. C. Saul, said that Captain Illingworth's name was familiar to anyone who had had any connection with ocean racing, and to most people who were interested in sailing. He was Commodore of the Royal Ocean Racing Club (RORC) and of the Royal Naval Sailing Association, and was a member of the Council of the Yacht Racing Association.

He had had many years' experience of long distance racing and had won his first championship in 1929. In 194; he had won the Sydney—Hobart race in Rani and in 1947 won the Fastnet and the Channel Race in Myth of Malham (Fig. 1). In 1948 he took part in the Bermuda race in Myth of Malham and then sailed back across the Atlantic to compete in the Santander and Belle He races. In the latter race he beat the whole ocean racing fleet boat for boat. In 1949 he again won the Fastnet Cup and also won the points championship over the whole season.

The International Maritime Consultative Organization (now IMO) carriage requirement for ARPA began to take effect in 1984 and became progressively mandatory worldwide; prior to this, for certain classes of vessels trading to the USA, a national requirement was introduced in 1982. These radar plotting aids perhaps constituted the first widespread use of computing power aboard merchant vessels. In implementation, even the early ARPAS were much more than the mere plotting aid which their name suggests. Sophisticated processing gave the navigator a system which offered significant assistance in scenario analysis, with the well known ability to display graphically the effect of a trial manoeuvre being the most active element of the system.

In this paper, a group of eight directional stones on the coral island of Arorae in the Gilbert Islands are described. The stones seem to have been used to direct canoe voyages to distant islands with the help of horizon stars en route, the stars' movements and bearings being studied and memorized in relation to the correct stone on the night before departure. They perhaps mark the site of a Polynesian navigation school which existed somewhere between A.D. 1000 and 1500. The directions given by the stones appear to have been corrected for drift due to the Equatorial Current. So far as is known these stones are unique, and have not previously been reported in print.

On the island of Arorae in the Gilbert Islands there is a group of eight or nine stones which are said by the natives to have been used by early canoe voyagers to set their courses on departure to distant islands. No other such stones for navigation have been reported from the Pacific, which makes the coral stones of Arorae of unique value in the history of navigation. The stones are some of the few pieces of real evidence in the long-standing controversy on the nature and range of Polynesian navigation. The stones are called ‘Atibu-ni-Borau’ by the natives, which means ‘stones for voyages’. They have no legends or traditions which shed any light on the origin or actual use of the stones, but there are several clues available from elsewhere in the Pacific which enable the use of the stones to be determined with a high degree of probability.

Recent progress in using real-time kinematic (RTK) positioning has motivated the exploration of its application due to its high accuracy and efficiency. However, poorly-observed satellite data will cause unfixed ambiguities and markedly biased solutions. A novel partial ambiguity resolution method, named the irrespective of integer ambiguity resolution (IIAR) model, is proposed and applied to improve the reliability of ambiguity resolution. The proposed method contains initial ambiguity resolution and irrespective of integer ambiguity processes. The initial ambiguity resolution process applies an iterative partial ambiguity resolution method to obtain an approximate solution. The irrespective of integer ambiguity process transforms the approximate solution to a high-precision solution. Experiments show that the approximate solution is unreliable when the initial ambiguity resolution process has small redundancy, and the proposed method can obtain better results for those cases. The IIAR method showed about a 40% improvement of multi-GNSS ambiguity success rate and about a 25% improvement of standard deviation. Therefore, these results show that the proposed IIAR method can improve the results of multi-GNSS RTK positioning significantly.

Oceanus is a hardware and software platform designed and developed to provide useful information to the crew of a racing yacht. The key features of the proposed solution are its reliability, the possibility to extend and customise it, and its context-awareness, which simplifies its usage in an intelligent way. The target users of the system are both beginners who want a navigation aid, but cannot afford the expensive and often overly complicated commercial systems available on the market, and more experienced sailors who can benefit from an open and customisable instrument to study and fine-tune the setup and performance of their sailing boats. Furthermore, Oceanus strives to be as much as possible a low-cost architecture, both in software and hardware requirements.

Connected and Autonomous Vehicles (CAVs) have been researched extensively for solving traffic issues and for realising the concept of an intelligent transport system. A well-developed positioning system is critical for CAVs to achieve these aims. The system should provide high accuracy, mobility, continuity, flexibility and scalability. However, high-performance equipment is too expensive for the commercial use of CAVs; therefore, the use of a low-cost Global Navigation Satellite System (GNSS) receiver to achieve real-time, high-accuracy and ubiquitous positioning performance will be a future trend. This research used RTKLIB software to develop a low-cost GNSS receiver positioning system and assessed the developed positioning system according to the requirements of CAV applications. Kinematic tests were conducted to evaluate the positioning performance of the low-cost receiver in a CAV driving environment based on the accuracy requirements of CAVs. The results showed that the low-cost receiver satisfied the “Where in Lane” accuracy level (0·5 m) and achieved a similar positioning performance in rural, interurban, urban and motorway areas.

People with physical disabilities often face many challenges due to the non-compliance of public buildings to accessibility standards. Hence, it is necessary to provide them with relevant information about the quality of access associated with the environment they plan to visit. In this paper, we propose ‘AccessVOR’ (Accessibility assessment based on VORonoï Diagram), a novel approach that aims to automatically generate an indoor navigation network and to assess its accessibility for people moving with wheelchairs based on the American with Disabilities Act Accessibility Guidelines (ADAAG). A semantically enriched spatial database is developed based on ADAAG and the Indoor Geography Markup Language (IndoorGML) standard. A Three-Dimensional (3D) navigation-graph is then generated from the various components of an indoor environment using a Voronoï Diagram. The semantics of ADAAG allow assessing the accessibility of each segment of this navigation graph. Next, a navigation cost is allocated to this graph based on the accessibility of each segment of the network graph for navigation purposes.

The CNS/ATM concept envisages reliance on global satellite navigation systems to underpin future air traffic management that is able to cope with the ever-increasing demand for air travel without jeopardising safety and the environment. In order to benefit from GNSS, it is crucial that the navigation performance required of air navigation systems is derived and agreed, based on sound principles. Significant work has been undertaken to date and agreement reached on the navigation requirements for the phases of flight up to Category I (CAT-I) precision approach, and proposals are under discussion for CAT-III precision approach. This paper completes a typical flight profile by addressing airport surface movement, and proposing the requirements based on operational requirements for each airport category, to support operations in zero visibility conditions. The benefits of the approach taken in the derivation of the requirements are discussed relative to the existing navigation requirements.

We present an approximation method for geodesic circles on a spheroid. Our ap­proximation curve is the intersection of two spheroids whose axes are parallel, and it interpolates four points of the geodesic circle. Our approximation method has two merits. One is that the approximation curve can be obtained algebraically, and the other is that the approximation error is very small. For example, our approximation of a circle of radius 1000 km on the Earth has error 1·13 cm or less. We analyze the error of our approximation using the Hausdorff distance and confirm it by a geodesic distance computation.

Every sailor, at the back of his or her mind, is aware that the nearest land is likely to be directly beneath the ship's keel and he or she is interested to know just how near. For over two thousand years, mariners measured depth of water by using a sounding rod in shallow areas and the lead and line in deeper water. This paper considers how, during the “Dark Ages”, sailors in the North Sea might have navigated, including the use of sounding rods and lead lines for way-finding during a time when no other navigational instruments were available. Because of the lack of contemporary records the authors firstly consider the use of depth finding in earlier and later times to shed light on how the early North Sea sailors might have operated. The latter part of this paper takes account of the earlier discussion, together with some records of North Sea voyaging, to suggest how “Dark Age” sailors might have used sounding rods, the lead and line, and other techniques to navigate around and across the North Sea.