The Position and Orientation System (POS) is a special Strapdown Inertial Navigation System (SINS)/Global Positioning System (GPS) integrated system, widely employed in airborne remote sensing. In-Flight Alignment (IFA) is an effective way to improve the accuracy and speed of initial alignment for an airborne POS. IFA is normally accomplished with references from the position and velocity of GPS for SINS, so that unstable GPS measurements will result in poor alignment accuracy. To improve alignment accuracy under unstable GPS conditions, an adaptive filtering algorithm of the Second-order Divided Difference filter (DD2) based on adaptive innovation estimation is proposed, which introduces calculated innovation covariance directly into computation of the filter gain matrix. Then, the adaptive DD2 algorithm is used for the IFA of the POS with a large initial heading error. To validate the proposed algorithm, simulations are undertaken, followed by IFA experiments for the prototype of the airborne POS (TX-F30) under a turning manoeuvre in a car-mounted experiment, and under an “8” manoeuvre in-flight. The simulations and experimental results show that the proposed algorithm can reach better alignment accuracy under unknown statistical characteristic of GPS measurement noises.

It is the common practice to draw great-circle tracks on gnomonic charts, on which they appear as straight lines, to pick off the latitudes of intermediate points where the track is intersected by the charted meridians, and finally to transfer the pairs of coordinates thus measured to a Mercator chart. The purpose of this note is to present the derivation of some formulae by means of which the coordinates of points along the track may be calculated very easily.

In our present age, radio communication and navigational aids are taken without comment throughout the aviation industry. However, all developments must start somewhere and it is the intention of this paper to look into the earliest days of “wireless” and its gradual application to aviation.

The first step was, as far as I can ascertain, in October 1866 when Mahlon Loomis flew a kite from a mountain top in Virginia, USA. He had fitted a copper mesh to the kite and connected this to a copper wire. Between the wire and earth he connected a galvanometer which, he noted, deflected from static electricity. On flying an identical kite at a similar height some fourteen miles away, if the copper wire were earthed, the deflection on the galvanometer changed. However, if the kite wires were of different length, this effect was not observed. For this, in 1872, he was issued with a US Patent 129971 for “wireless telegraphy” but, as far as we know, apart from a few fading freehand notes, (See Figure 1) no details of his apparatus survive, so it must remain a matter of conjecture what was actually achieved.

The first scientific instrument to be designed specifically for use at sea was the mariner's astrolabe. The cross-staff or Jacob's staff had been used by astronomers since the Middle Ages, and the magnetic compass used by navigators had long been familiar as an aid to land travel, a means of setting portable sundials, and in the east, a device for divination.

Language holds many pitfalls for the unwary. A housewife picks up her iron, and so does the golfer: a butcher uses the steel and so does the soldier: a government nationalizes iron and steel. No wonder the foreigner makes ludicrous mistakes. And we in our turn, coming across an Italian book entitled Il Compasso da Navigare might be pardoned for supposing its subject-matter to be the navigating compass. This is not so. It is a learned and comprehensive treatise under the title belonging to the oldest surviving Sailing Directions for the Mediterranean Sea, and as the author, Bacchisio R. Motzo, clearly proves, such Directions were called a Compasso, and by a natural transference the same name was given to the sailing chart which was drawn to accompany the Directions. What we call a mariner's compass, or simply a compass, the Italians term Compasso-bussola or more usually just bussola. When English sailors began to use written Directions or ‘Pilots’ they called them Rutters (from the French Routier), while an alternative Italian name for a Compasso was Portolano, which also meant the accompanying chart.

In many aviation and nautical contexts, single manning is common. Some aircraft and some vessels are designed for single manning with no choice. Others can have multiple or single manning, usually depending on such factors as operational requirements, mission objectives, intended human roles, task demands, workload, envisaged mission duration, and environmental conditions.

The author is Professor of Oceanography in the School of Engineering and Science of New York University and this paper was prepared for the Imco joint ad hoc group for the study of external forces affecting ships. Reviewing the circumstances attending the loss of the trawlers Blue Crusader and Boston Pionair in 1965 he attributes them to high pyramidal seas caused by the crossing of wave trains refracted in water of varying depth. The use of model experiments, air photography and laser altimeters is suggested for verifying the theoretical conclusions, in the light of which corrective measures might be taken when navigating under such conditions.

Inspired by Professor Kemp's historical article on the use of soundings in navigation, this contribution provides useful information on the use of leadlines in commercial fishing and the Royal Navy in the mid-20th Century.

Benefiting from video surveillance systems that provide real-time traffic conditions, automatic vessel detection has become an indispensable part of the maritime surveillance system. However, high-level vision tasks generally rely on high-quality images. Affected by the imaging environment, maritime images taken under poor lighting conditions easily suffer from heavy noise and colour distortion. Such degraded images may interfere with the analysis of maritime video by regulatory agencies, such as vessel detection, recognition and tracking. To improve the accuracy and robustness of detection accuracy, we propose a lightweight generative adversarial network (LGAN) to enhance maritime images under low-light conditions. The LGAN uses an attention mechanism to locally enhance low-light images and prevent overexposure. Both mixed loss functions and local discriminator are then adopted to reduce loss of detail and improve image quality. Meanwhile, to satisfy the demand for real-time enhancement of low-light maritime images, model compression strategy is exploited to enhance images efficiently while reducing the network parameters. Experiments on synthetic and realistic images indicate that the proposed LGAN can effectively enhance low-light images with better preservation of detail and visual quality than other competing methods.

The probability of a human-caused incident occurring during dynamic positioning (DP) drilling operations is determined in this paper using binary logistic regression models built with data on 42 incidents that took place during the period 2011–2015. For each case, a range of variables characterising the configuration of the DP system, weather conditions and water depth are taken into account. These variables are taken into account to develop a logistic regression model that shows the likelihood of an incident being caused by human error. The results obtained show that human-based incidents are significantly more likely to occur when there is a lower usage of thrusters. These results are useful for focusing our attention on variables that may be associated with incidents attributable to human error, as well as for setting operational limits that could help to prevent these incidents and improve safety during these operations.

Significant developments have taken place in navigation and positioning techniques at sea. These include radio, acoustic and inertial methods, and satellite based techniques. The latter consist of the Transit Doppler system, which has now been in operation for over 20 years, and the Global Positioning System which is due to be inaugurated in the early 1990s. These various systems are described in the paper, and their marine engineering, geodetic and geophysical applications discussed. The paper is based on a lecture presented at the Oceanology International Conference held at Brighton in March 1986.

Digital maps have a large potential to support safety-related Advanced Driver Assistance Systems (ADAS) by providing detailed road and environment information. However, one critical attribute – road accident hotspot – is not available from existing digital maps, and is also difficult to derive from practical surveying. This paper provides a Geographical Information Systems (GIS)-based approach for the production of digital hotspot maps, based on a historical accident dataset and geospatial methods in a GIS. In this approach, firstly the Kernel Density Estimation (KDE) method was used to identify hotspot distribution; secondly the Percent Volume Contour (PVC) method was coupled with KDE to extract hotspot patterns; and finally the map layers of hotspot patterns were integrated with classical navigation maps. Following a description for geospatial hotspot production, the derivation of hotspot property data is also discussed. In order to prove this approach, a small-area case study was carried out in the City Centre of Nottingham. The presented results demonstrate that this approach is useful and effective for solving the hotspot creation problem for ADAS, but other future works will be required to improve data effectiveness.

In the second issue of the Journal a system of grid navigation was described. This system warrants serious consideration because of its application to polar navigation and because it offers a means of simplifying navigation in high-performance single-seater aircraft of long range. These aircraft are going to present extreme difficulties, particularly in naval aviation, where fixing facilities and pilotage are limited.

Advanced vehicle navigation based on the US Global Positioning Systems (GPS) will play a major role in future vehicle control systems. Contemporary vehicle navigation systems generally consist of vehicle positioning using satellites and location and orientation of the vehicle with respect to the roadway geometry using a digitised map on a CD-ROM. The standard GPS (with Selective Availability) enables positioning with an accuracy of at least 100 m and is sufficiently accurate for most route guidance tasks. More accurate, precision navigation can be obtained by Differential GPS techniques. A new light concept called Adaptive Light Control (ALC) has been developed with the aim to improve night-time traffic safety. ALC improves the headlamp illumination by means of continuous adaptation of the headlamps according to the current driving situation and current environment. In order to ensure rapid prototyping and early testing, the step from offline to online (real-time) simulation of light distributions has been successfully completed in the driving simulator. The solutions are directly ported to real vehicles to allow further testing with natural road conditions.

An aircraft wing is the carrier of imaging payload (interferometric synthetic aperture radar (SAR) or array SAR) of a high-resolution aerial remote sensing system, and high-precision estimation of wing deformation is the key. There are two main traditional modelling methods for wing deformation, namely stochastic theory modelling and material mechanics modelling only dealing with single disturbance, of which the model parameters are derived from empirical values. Aiming at the complex multi-source disturbance of an aircraft wing, this paper separately probes the influence of external disturbance (air disturbance) and internal disturbance (engine vibration) based on the real-time observation of sensors and classifies the wing deformation on the basis of auto-regressive (AR) modelling for parameter identification. With the authentic flight data of a certain types of aircraft, the experimental analysis shows that the wing deformation under the influence of engine vibration is the 14th-order AR model, and the wing deformation under the influence of turbulence is the fifth-order AR model. Meanwhile, this paper also provides an experimental verification idea for the wing deflection modelling built on the second- or third-order Markov model.

A priori attitude information can improve the success rate and reliability of Global Navigation Satellite System (GNSS) multi-antennae attitude determination. However, a priori attitude information is nonlinear, and integrating a priori information into the objective function rigorously will increase the complexity of an ambiguity domain search, such as the Multivariate Constrained-Least-squares Ambiguity Decorrelation Adjustment (MC-LAMBDA) method. In this paper, a new method based on attitude domain search is presented to make use of the a priori attitude angle information with high efficiency. First, the a priori information of pitch and roll is integrated into the search process to derive the analytic search step for attitude angle, and the integer candidates are determined by traversal search in the three-dimensional attitude domain. Then, the objective function is parameterised with Euler angles, and a non-iterative approximate method is utilised to simplify the iterative computation in calculating objective function values. Experimental results reveal that compared to the MC-LAMBDA method, our new method has the same success rate and reliability, but higher efficiency in making use of a priori attitude information.

One of the popular techniques for solving GPS pseudorange nonlinear quadratic equations to obtain the receiver's position and clock bias involves linearizing the equations and solving them by the least-squares (LS) scheme, which is based on the L2 minimization criterion. When outliers are a problem, LS estimation scheme may not be the best approach because the LS estimator minimizes the mean squared error of the observations. This paper discusses the implementation aspects of L1 and L∞ criteria, and their outlier resistance performance for GPS positioning. Three ordinary differential equation formulation schemes and corresponding circuits of neuron-like analogue L1 (least-absolute), L∞ (minimax), and L2 (least-squares) processors will be employed for GPS navigation processing. The circuits of simple neuron-like analogue processors are employed essentially for solving systems of linear equations. Experiments on single epoch and thereafter kinematic positioning will be conducted by computer simulation for investigating the outlier resistance performance for the least-absolute and minimax schemes as compared to the one provided by the least-squares scheme.

In a series of three papers Dr Lewison has described the progressive results of a line of research which may have important applications in the consideration of routing schemes. The first paper described a mathematical model which can predict the number of encounters that would occur between ships of different traffic streams in the absence of avoidance manœuvres. In the second paper the number of potential encounters was calculated from estimates of traffic flow, in a particular area of the Dover Strait, then compared with the number of actual collisions to determine the risk of a ship encounter leading to a collision. The third paper updated these results for the Dover Strait and suggested how estimates of collision risk could be made for other UK coastal areas.

‘Close-quarters situation’ is a term used in the International Regulations for Preventing Collisions at Sea. As the term is not precisely defined, this paper analyses the interpretations and definitions of the term by various authors or courts, based on judicial processes and judgments. In the end, the authors suggest their own definition of the term ‘close-quarters situation’. Knowing the minimum distance from another ship and the time to the closest point of approach at which collision may still be avoided by one's own manoeuvre is information that every ship's officer needs to know. In accordance with the proposed definition of the term ‘close-quarters situation’, minimum distances between ships and time to the closest point of approach in which the ship can still take action to avoid a collision by its own manoeuvring are determined by means of simulations on a navigational simulator. A total of 168 simulations were performed with three fine-form vessel sizes and three full-form vessel sizes. Due to the extensive amount of data, the paper presents the results for one vessel only.