The possibility of reducing the current vertical separation minima in order to increase traffic capacity on economical flight levels has been discussed mainly at the RGCSP (Review of the General Concept of Separation Panel) meetings of ICAO. A collision risk model based on the mathematical model developed by Reich (1966) has been adopted for evaluation of safety of air traffic systems under consideration. This collision risk approach requires several parameters which should be estimated from empirical data on navigational errors, traffic dynamics, etc.

Since 1975 the Royal Netherlands Naval College has operated a bridge manoeuvring simulator for the training of naval officers and petty officers of the deck department. There is a strong relationship between training objectives and performance abilities of a simulator and the way the two match defines the cost effectiveness and the value of simulator training. The training objective being the result aimed at (for a professional watchkeeper) consists partially of a combination of training subjects (things to be learned at the simulator). During 1980 and 1981 R.Nl.N.C. conducted a survey on simulator training subjects by means of an inquiry amongst Royal Netherland's Navy and Merchant Navy officers, marine lecturers (all of Dutch origin) and members of the International Marine Simulator Forum (IMSF). The results form the subject of this note.

The pioneers of air navigation used a simple magnetic compass as a heading reference. At first boat or surveying compasses were used but these were not really satisfactory for use in aircraft, as engine vibration caused them to rotate. The first successful magnetic compass for aircraft use was the Creigh–Osborne compass which took to the air on 27 October 1909, in the British Army Aeroplane flown by the celebrated Col. S. F. Cody. In the years following and throughout World War I magnetic compasses based on this early work, with either horizontal or vertical cards, were widely used.

Many nations are debating the implementation of vessel traffic services (VTS) and it is envisaged that some regulation of the movement of marine traffic may soon be imposed. It is highly desirable that prior to any change a rigorous appraisal of the existing traffic be carried out to establish the level of risk in the area; this level can then be used to evaluate any proposed change. The following note describes a research project concerned with establishing a general method of determining the base risk level, developed from earlier research by M. Degré and M. Lefèvre who used a computer simulation of marine traffic in the Dover Strait to assess the impact of various suggested traffic separation schemes. A cost-effective tool has been developed at Liverpool which will enable traffic patterns to be studied in areas remote from the land. This is a computer simulation model which is being used to establish dynamic areas of risk in the Irish Sea, which could easily be transposed to study traffic patterns in any other area.

Even today much time is lost in bringing effective help when an accident with a truck carrying dangerous goods occurs. The location of the accident is often not well described by the people reporting it. Often it is difficult to determine what sort of freight a lorry is carrying, for example when the vehicle is burning, and sometimes the fire brigade does not bring the appropriate extinguishing equipment for the first help approach. Now an emergency location system is under development which will remove all these disadvantages. For immediate help on car accidents, an automatic alert message is transferred from the crashed vehicle via the emergency call centre to the fire brigade, the police station or the headquarters of an ambulance. The alert is initiated by a crash sensor within the car or the truck. The data channel between vehicle and base can be a radio link or, for longer distances, a mobile telephone connection using CNET or GSM. AS help is faster and more effective with this system, environmental damage caused by dangerous goods can be reduced.

In Stuttgart the mobile part of the DGPS-based emergency location system has been integrated in several vehicles. The full system is being tested within a field trial of a pilot project called STORM (Stuttgart Transport Operation by Regional Management), which is part of a programme of the European Community. The results of these tests are summarized in this paper. The integration of the system into fleet management applications is also considered.

The geometry of the skeg in the Escort Tractor Voith tugs is the result of a series of intense investigations in the forms of the tug and its fins, oriented to get a significant improvement in the forces on the towing line when the indirect method is used in the escort towing. For that, and with the aim of getting the best behaviour of this fin, a variety of options have been investigated for years, evaluating its merits in terms of lift force and complexity to reach the present designs, which are adapted to the functions which the tug is destined to carry out. With the object of optimizing the lift force in the skeg when the indirect method is used in the escort towing, and after long investigations, the Voith Turbo Marine has incorporated a rotating cylinder at the leading edge to its design in escort towing for the first time at the beginning of 2005. The leading edge is the part over which the water flow first falls upon in normal escort operation conditions, calling this new development Voith Turbo Fin (VTF) to the system as a whole (skeg and rotating cylinder). This fin is analyzed in this article especially with regard to its basis, ways of operation and efficiency of the novel joining rotating cylinder.

Global navigation satellite system (GNSS) receivers meet numerous challenges in a high-orbit environment, including weak and discontinuous signal, and time-varying strength. To resolve these issues and enhance reliability, an innovative adaptive vector tracking loop (VTL) scheme is proposed. Non-linear models of the VTL filter are established to calculate code phase and carrier frequency errors accurately. Based on this, a deep analysis has been developed on the measurement noise. To reduce the impact of the interdependent noises among channels in VTL, an adaptive VTL algorithm assisted by the variational Bayesian (VB) learning network is proposed to estimate the measurement noise and maintain the error convergence in the time-varying noise or signal outage conditions. Further, the implementation steps of the adaptive algorithm have been designed in detail. In particular, the carrier-to-noise power ratio (C/N0) estimation method is further employed to update the a prior probability density in case of change of tracking satellite. The simulation results indicate that the proposed VTL scheme with VB algorithm is a promising method to improve the accuracy and reliability of GNSS receivers significantly under a high-orbit degraded signal environment.

‘The Earth is an ellipsoid’, says the Admiralty Navigation Manual firmly, although in a later volume the expression is softened to ‘approximately ellipsoidal’, For in fact, as was implied by Captain Topley, the exact shape of the Earth is not yet known. Nevertheless, for nautical purposes it appears sound teaching practice to consider it a perfect sphere and then explain the departures of the nautical mile or minute of arc from its mean value. Nor need one quarrel with the Manual's statement that ‘to regard certain small triangles as plane is not to disregard the initial decision to regard the Earth as a sphere’. But the writer next indulges in an historical aside which cannot be allowed to pass. ‘This assumption (he says) gives rise to the expression plane sailing, which is popularly referred to as if plane were spelt plain and the sailing were free from difficulty’. But this is to put the cart before the horse. ‘Plain sailing’ was the original term, and it was only sophisticated into ‘plane sailing’ during the eighteenth century by teachers of navigation among whom John Robertson was the chief. Robertson was master at the Mathematical School of Christ's Hospital towards the middle of the century, and afterwards taught at the Portsmouth Naval College, finally becoming Librarian to the Royal Society. His Elements of Navigation was considered authoritative and ran into many editions, a later master at the Hospital, James Wilson, prefixing to it a Dissertation on the history of navigation which was also accepted as definitive. It is in this volume that we read: ‘Plane sailing is the art of navigating a ship upon principles deduced from the notion of the Earth's being an extended Plane. On this supposition the meridians are esteemed as parallel right lines…’, and the author goes on to what he terms the Plane Chart, with its equally-spaced meridians. There is little doubt that his passage is the source of the theory taught to modern sailors that ‘Plain Chart’ is a corruption of ‘Plane Chart’, while the latter was drawn by people who believed the Earth was flat. Actually we have only to go back a generation from Robertson to find an almost identical description of the chart—actually an equal-spaced conventional cylindrical projection of the sphere—but with the addition of the words ‘The rectangle formed by these meridians and parallels they (i.e. mariners) call the Plain Chart’. This was said in 1714 by John Wilson, a teacher in Edinburgh.

The first amazement at hearing of the successful launching of the Russian Earthsatellite in October may have been followed in the reader's mind by some bewilderment at its rapid and seemingly erratic progress over all the world's capitals, large cities and outlying island groups. One supposed that a mathematical prediction would be possible but hesitated to attempt anything so complex. Yet, with some simplifying assumptions which must in any case be rather closely approximated by any near satellite that can continue to rotate in orbit, the problem is not difficult and lends itself to graphical treatment. The construction here proposed will give a good insight into the behaviour of such satellites and provide reasonably accurate predictions for a day or two ahead.

The ranging accuracy provided by pseudorange-only techniques is usually no better than a few metres when no differential corrections are applied. Carrier-phase algorithms, on the other hand, yield higher-precision estimates – down to a few millimetres – but are prone to ambiguities difficult to resolve. An easier-to-implement method, using single-frequency pseudorange measurements only, is presented. It allows for a decimetre-level relative positioning accuracy. Results, derived from the GPS Relative Positioning Equations, are validated with actual satellite data from the Gravity Recovery and Climate Experiment (GRACE) mission.

A local positional system (LPS) is proposed, in which particles are launched at given velocities, and a sensor system measures the trajectory of the particles in the platform frame. These measurements allow us to restore the position and orientation of the platform in the frame of the rotating Earth, without solving navigation equations. When the platform velocity is known and if the platform orientation stays the same, the LPS technique allows a navigational accuracy of 100 $\mu$m per one hour to be achieved. In this case, the LPS technique is insensitive to the type of platform trajectory. If there are also velocimeters installed on the platform, then one can restore the platform velocity and angular rate of the platform rotation with respect to the Earth. Instead of navigational equations, it is necessary to obtain the classical trajectory of a particle in the field of a rotating gravity source. Taking into account the gravity-gradient, Coriolis, and centrifugal forces, the exact expression for this trajectory is derived, which can be widely used in atomic interferometry. A new iterative method for restoring the orientation of the platform without using gyroscopes is developed. The simulation allows us to determine the conditions under which the LPS navigation error per hour is approximately $10$ m.

This year marks the twentieth anniversary of the introduction of Concorde into commercial airline service. The first commercial flights were on 21 January 1976 – British Airways from Heathrow to Bahrain and Air France from Paris to Rio via Dakar. Later in that year commercial flights to Washington/Dulles began on 24 May. Services to New York were delayed until 22 November 1977. The first flight of Concorde was some seven years earlier. The prototype took off out of Toulouse on 2 March 1969 and this was followed by 002 from Filton to Fairford on 9 April. At the time it was anticipated that this was the beginning of an era when supersonic flight would be the normal way to travel long distances. Now, in 1996, Concorde is still the world's only supersonic commercial passenger airliner in airline service. This is an extraordinary achievement. The Boeing SST proved to be too ambitious and the programme was halted in 1971 after the United States Government withdrew support, while the Russian TU 144 was beset with problems. One TU 144 crashed at the Paris Air Show in 1973. The aircraft entered internal airline service in December 1975, flying supersonically between Moscow and Alma-Ata, capital of Kazakhstan, carrying mail and freight, but it did not have the range to operate viable intercontinental passenger serives. Certainly by 1985, if not many years before, the TU 144 was out of service.

There is a fast growing realization that the Steering Rules in the Regulations for Preventing Collisions at Sea should be attuned to the use of radar. The principle underlying the suggested rules which follow is to stick to the idea of Rule 18—that in case of risk of collision both vessels should take avoiding action. In order to make these rules practicable, a universal system has been thought out. Thus, the rules are meant to apply to vessels in sight of one another, as well as to vessels in radar-contact, or to a vessel in radar-contact with another vessel which is unaware of her presence. Secondly, there will be one and the same rule for power-driven vessels and sailing vessels.

This paper describes three different antenna systems for mobile vehicle applications. The antennas are either patches or derivatives in all cases. The first is a dual-band telephone antenna with a low profile and wide bandwidth. Operating at 900 MHz and 1800 MHz, with a VSWR of better than 1·7, it is a hybrid construction combining a monopole with a top-loading patch shorted to the ground-plane. Extra-shorted pins provide the upper frequency band coverage. It provides monopole radiation characteristics and can be hidden under a plastic panel or mounted on the vehicle roof. The second is a microstrip patch antenna integrated into a laminated glass windscreen for a vehicle. It is fed using a coplanar waveguide feed printed on the innermost layer of the glass, avoiding the need for a contacting feed within the laminate. The patch and ground plane are meshed for manufacturing in the glass to avoid distorting the heat profile when the glass is shaped and laminated. The patch is easily fed from inside the vehicle and is potentially a very low cost design. The final antenna discussed is a dual-band patch antenna specifically designed for the Globalstar satellite telephone system at 1·6 GHz and 2·45 GHz. It also covers the Iridium band at 1·6 GHz. A single circularly polarised patch is used. Dual-band operation results from truncating the corners of the square patch and judiciously placed slots to achieve a band spacing of 1·5.

A dynamic state realization for tightly coupling Global Positioning System (GPS) measurements with an Inertial Navigation System (INS) is described. The realization, based on the direct fusion of GPS and INS systems through Kalman filter state dynamics, explicitly accounts for temporal and spatial decorrelation of GPS measurement errors (such as tropospheric, ionospheric, and multipath errors) through state augmentation, thereby ensuring Kalman filter integrity under fault-free error conditions. Predicted system performance for a Local Area Augmentation System (LAAS) aircraft precision approach application is evaluated using covariance analysis and validated with flight data.

Built-in fault detection mechanisms based on the Kalman filter innovations are also evaluated to help provide integrity under certain fault conditions. It is shown that an algorithm based on the integral of Kalman filter innovations outperforms other existing GPS fault detection methods in the detection of slowly developing ranging errors, such as those caused by ionospheric and tropospheric anomalies.

This paper tackles the Equatorial ionosphere and its effects on Differential Global Positioning System (DGPS) error growth over Malaysia by using a network of GPS Continuously Operating Reference Stations (CORS). Seasonal variation of ionospheric delay has been examined and findings show that the effect of spatial variation of ionospheric errors in DGPS is very significant during the equinoctial seasons. Furthermore, a DGPS regression model was developed and tested during the solar maximum year in 2013 by using internet-based DGPS. The results show that the model is capable of estimating DGPS positional errors for distances of user to reference station less than 680 km.