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.

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.

I must forewarn you that this lecture will deal only with very elementary mathematics. Its subject is what may be termed the preparatory school stage in the education of the navigator. Nevertheless, it is a subject of particular interest and importance because it is in the field of navigation that we first meet with mathematics quite outside learned academic circles. It was among sailors that the process was begun (and it is not yet complete) of transforming the craftsman—whose skill rests on tradition and experience—into the technician—who works on established scientific principles. For the scholar, mathematics is like poetry—an end in itself.

With the growth of public air transport, safety in the air is a matter of concern not just to those who design, manufacture and operate aircraft, but to the public at large. After an accident has occurred and an unfortunate chain of events leading to the accident is exposed, it may be easy to say ‘this accident should not have occurred’ or ‘would not have occurred if…’. Publication of annual totals brings forth informed and uninformed comment on the apparent decrease or increase in the accident rate relative to some criteria such as the number of passenger kilometres flown. The objective of this paper is to present a scientific account of the evidence on the relationship between navigation and air accidents and the implications of this evidence for those who are professionally concerned with air navigation. As will become evident, how-ever, there are factors operating which go much deeper than the technical aspects and appear to have their roots in human behaviour, not just of the individual but of organizations and society as a whole.

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.

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.

This paper was presented at the RIN89 Conference on Orientation and Navigation – Birds, Humans and other Animals. The conference was held in Cardiff in 04 1989. The printed proceedings contain some 27 papers and are available by application to the Director. The price is £30 (RIN Members) or £35 (Non-Members).

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.

Most navigators will, at some time or another, have noticed the effect of changes in humidity on the dimensions of paper maps or charts pinned up for display purposes. A display chart, or any other large sheet of paper, neatly pinned to a notice board in a warm dry room will tend to sag in an untidy manner if the atmosphere is allowed to become damp. Similarly a chart pinned up in a moist atmosphere is liable to contract and tear away from its anchoring pins if the weather becomes warm and dry. In the same way, the size of a paper chart in use in the air will vary appreciably with changes in atmospheric conditions; and it follows that if the size changes, so does the true scale. Such changes in the scale are of little consequence so long as dividers are used for measuring distances, since it can be assumed that the distance graduations on the chart all expand and contract in proportion to the change in size of the sheet as a whole. But if a graduated rule or straight-edge is used (and this is practicable only in the case of maps or charts based on some projection giving near-constancy of scale) then, quite apart from the scale errors of the projection, changes in the size of the chart will give rise to errors.

Cadets training to become licensed mariners based on the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) Code have been under pressure to keep up with the countermeasures against COVID-19 from the Spring of 2020. For several reasons, sea training voyages were restricted or cancelled, and the schooling style was drastically changed from face-to-face to remote. Since the research vessel owned by Tokai University is not a training vessel exclusively for cadets, the decision was inevitably made to make more effective use of the shiphandling simulator. Because training in the simulator also had to be done remotely, new ideas were put into practice to explore the possibility of building new educational methods. Numerous open-ended evaluation comments were submitted by the cadets who received remote training on the simulator. The results suggested that the remote use of the simulator is likely to be an effective method for training in bridge resource management (BRM).

What are the major factors contributing to ship accidents, and how do these factors evolve in the long term? This study addresses these two questions by leveraging an unsupervised machine learning method named structural topic modelling to identify the causes of ship accidents. The study analysed 2,341 task errors manually collected from 441 reports issued by four government agencies covering a 45-year time span. The results show that the structure of causes of ship accidents remained essentially the same during this period. This highlights the social-material aspect of navigation technology, indicating that the use of advanced technology may not necessarily lead to safer navigation practices, and the interaction between the technology and human agency must be focused on in the bridge management context. Additionally, the computer-assisted textual data analysis highlights pilot-related factors, which might be rooted in the unsupervised and difficult-to-verify handover procedures between pilots and captains, thereby underlining the importance of appropriate piloting regulations.

Multipath propagation can cause significant impairments to the performance of Global Navigation Satellite System (GNSS) receivers and is often the dominant source of accuracy degradation for high precision GNSS applications. Commonly used time-of-arrival estimation techniques cannot provide the required estimation accuracy in severely dense multipath environments such as urban canyons. Multipath components are highly correlated and this results in a rank deficiency of the signal autocorrelation matrix. In this paper the Doppler spectrum broadening of the fast fading channel resulting from the motion of the receiver or surrounding objects is employed to decorrelate signal reflections for the purpose of high-resolution estimation of multipath delays through the subspace-based Multiple Signal Classification (MUSIC) technique. Specifically, delay-domain correlator outputs at different Doppler frequencies are combined to enhance the rank of the signal autocorrelation matrix. Simulation and results of real data collected in an urban environment (downtown Calgary) are presented to compare the performance of the proposed method with the spatial-temporal-diversity-based MUSIC technique and a widely available algorithm in commercial GNSS receivers, namely the double-delta correlator technique. The performance metrics are based upon pseudorange and positioning errors, which are derived using an accurate reference trajectory established using a high precision GNSS-INS integrated system.

Most lists of the seven wonders of the world include the Colossus of Rhodes. This bronze figure of Apollo, which the sculptor Chares took several years to construct, stood near a harbour on the island of Rhodes in the Eastern Mediterranean. It is reported that ships in full sail could pass between its legs whilst navigation lights were kept burning in its eyes. Whilst such descriptions are coloured by romance and myth, there is little doubt that early lighthouses were substantially tall towers supporting an open wood or coal fire. Such lights existed in Britain until as late as 1819, when Flathom light in the Bristol Channel was replaced by more modern equipment.

In time the open-flame coal brazier gave way to tallow candles. In 1696 Winstanley introduced a chandelier with tallow candles into the lantern of his famous Eddystone Tower. In 1759 Smeeton's Tower, which now stands on the Hoe at Plymouth, incorporated two superimposed iron rings that contained twenty-four candles.

By and large it was the improvements in optical systems that governed the development and introduction of oil and then, at a later date, electric illuminants.

The first attempt to intensify a lighthouse beam was in 1727 by the French at Cordouan. Mariners had complained that they could not see the light at more than 2 miles. In an attempt to improve on this, a cone of wood was covered with tin plate and suspended above the open fire.

This study aims to examine the predictors of professional commitment of the Chinese new generation, divided into post-80s and post-90s cohorts. A questionnaire survey was employed to collect data from Chinese seafaring officers of these cohorts. The results through hierarchical regression analysis present the two cohorts as having both similar and different predictors. The main difference is that company management and policies positively drive the post-80s cohort to work at sea but not the post-90s. The main similarity is that the work itself is the most important predictor for both cohorts. This study contributes to helping maritime companies to estimate the possibility of Chinese new generation officers quitting sea jobs and can be of value to both managers and authorities as they seek to comprehend the generational dynamic features to better cope with the problem of shortage of younger qualified officers.

Signal-In-Space Error (SISE) is important for the system integrity of GNSS. Real-time monitoring SISE has been one of the effective solutions used for improving GNSS system-level integrity. As one of the typical solutions, the Galileo integrity concept uses Signal-In-Space Accuracy (SISA) and Signal-In-Space Monitoring Accuracy (SISMA) respectively to transmit the quality of SIS and the integrity alarming information to users. As an important component of the Galileo Integrity Concept, Worst User Location (WUL) is of great importance for the computation of SISA and SISMA. An improved WUL algorithm based on a geometrical model is given in this paper, which needs no iterative search and is simple when compared with the existing models. The WUL accuracy requirement is discussed based on an analysis of the magnitude of the orbit errors and SIS ranging resolution and error. The conclusion is that, considering the metre-level orbital error observed in the orbit determination process, as long as the orientation error of the WUL is less than three degrees, the projection error of SISE can be kept to centimetre levels. This will satisfy the requirements of most users. The algorithm is further optimised to omit the non-linear iterative parts based on the above assumption. The optimisation reduces computation load and enhances the real-time capability. GPS raw measurements are used to validate the correctness and reliability of the algorithms.

The sight-run-sight case involves a series of two or more sights in which each sight is ‘run on’ to the time of the last sight. There are several known techniques to account for the run, which is for convenience assumed to be at a constant course. It is argued that only the GHA-Dec updating technique (GD-UT) will give a correct position solution, whereas the pre-electronic Intercept Method (IM)-based technique and its modern least-squares variant (LSQ) and the Altitude updating technique (A-UT), are proxy techniques that may yield significant deviations in position solution. GD-UT can be used in combination with a double-sight solution method for two sights and with LSQ for two or more sights. IM, LSQ and a geometric or algebraic double sight solution method applied to simultaneous double sights give identical results but the simultaneous sights case is generally an abstraction and strictly not applicable on a moving vessel.

In C-Band transfer measuring systems, the Precise Orbit Determination (POD) precision of Geostationary Earth Orbit (GEO) satellites is limited by signal biases such as the station delay biases, transponder delay biases, the ionospheric delay model bias, etc. In order to improve the POD precision, the signal biases of the Chinese Area Positioning System (CAPS) are calibrated using Satellite Laser Ranging (SLR) and C-Band Transfer Ranging (CBTR) observations. Since the Changchun SLR site and C-Band station are close to each other, the signal biases of the Changchun C-Band station are calibrated using the co-location comparison method. Then the signal biases of the other two CAPS C-Band stations, located in Linton and Kashi, are calibrated using the combined POD method, with the signal biases of the Changchun C-Band station being fixed. After the signal biases are calibrated, the RMS of the line-of-sight residuals of the Changchun SLR observations decrease by 0·4 m, with the percentage improvement being 75·19%.

The associate members of the North European LORAN-C System (NELS) will, before the end of the six-nation co-operation agreement in 2004, need to take a decision whether to prolong or decommission LORAN-C operation in Europe. The Minister of Fisheries in Norway has already indicated decommissioning of the Norwegian LORAN-C stations. Such a decision raises the fundamental debate about whether we can rely on GPS as a ‘sole-means’ system, or if we need a secondary backup system, such as LORAN-C. The purpose of this article is to highlight important aspects and conflicts related to an extension of LORAN-C in Europe. The focus will therefore be towards the limitations and vulnerability of GPS vs. the potential of LORAN-C improvements. The discussion will be based on a Norwegian nautical perspective.

To achieve more accurate navigation performance in the landing process, a multi-resolution visual positioning technique is proposed for landing assistance of an Unmanned Aerial System (UAS). This technique uses a captured image of an artificial landmark (e.g. barcode) to provide relative positioning information in the X, Y and Z axes, and yaw, roll and pitch orientations. A multi-resolution coding algorithm is designed to ensure the UAS will not lose the detection of the landing target due to limited visual angles or camera resolution. Simulation and real world experiments prove the performance of the proposed technique in positioning accuracy, detection accuracy, and navigation effect. Two types of UAS are used to verify the generalisation of the proposed technique. Comparison experiments to state-of-the-art techniques are also included with the results analysis.

The Safety Level Approach (SLA) is a structured application of risk-based methodologies for the International Maritime Organization's (IMO's) rule-making process. When the SLA is applied, safety goals have to be provided. In order to set appropriate levels for safety goals, it is necessary to measure the tolerance degree of the current safety level. Based on the consistency with individual risk criteria and the principle of continuous improvement, this paper proposes an approach to establish the societal risk criteria, which can be used for setting safety goals in the context of the IMO's SLA. Furthermore, by defining dynamic factors to express risk aversion, a method for tolerance measurement of the current societal risk is developed. Finally, a case study into the societal risk evaluation of cruise ships and Roll-On Roll-Off (RO-RO) passenger ships is conducted.