A review of the nuclear magnetic resonance gyroscope (NMRG) as a rotation-rate sensor is presented. Most of the activity in the recent past on NMRG research originated in the USA and concentrated almost exclusively on forms of the NMRG utilizing optical-pumping techniques. To date, only the National Air Defence Centre at Warminster, Pennsylvania continues to pursue a low-cost variant of the NMRG while in the UK, only ARE (Slough) and Sussex University remain active in NMRG research. The emphasis on activity in the Navigation Division at ARE (Slough) has continued to be on cryogenic helium-3 (3He) techniques and the use of superconducting shielding (although optical-pumping will also be pursued). The continuing incentive for NMRG research remains the requirement for a ship's low-cost inertial navigation system (SLINS).

This paper describes the application of navigational ideas during a late stage of the Yorkshire Ripper investigation. The conclusions reached were irrevocably recorded before the ultimate facts were established by the arrest and conviction of the killer. The reader is invited to assess the degree of success of the method and to rework the data supplied according to his own navigational ideas. The suggestion is made that navigational concepts may become a valuable weapon in the field of crime investigation.

Traditional receivers for the low-frequency, hyperbolic radio-navigation systems – Loran-C, Decca Navigator and Omega – are expensive and are operated manually. They either display position fixes in hyperbolic coordinates for plotting by hand on navigation charts printed with hyperbolic overlays or they plot tracks automatically, often on distorted charts. Recently, low-cost receivers have been developed for marine navigation which operate wholly or largely automatically and which display position measurements in geographical coordinates – latitude and longitude – or as headings and distances to waypoints which are entered by the navigator in geographical coordinates.

This paper touches on some of the problems with which the chart compiler has to contend in an area such as the Gulf of Suez. It is assumed that readers are familiar with the system of keeping charts up to date through Notices to Mariners and new editions of charts. Details of the system can be found in The Mariner's Handbook. Space does not allow a full evaluation of all the influences source data for charts may have on the final product, and in particular no treatment is given here of one significant area, the influence of source data on choices of chart limits and scales. The paper will look first at some more general points which find expression in the charting of the Gulf of Suez, and then take as an example chart 2375 of the Strait of Gubal, examining aspects of it in detail in the light of the general points raised.

This paper was presented at an International Conference on ‘Navigation in the Gulf of Suez’ held in Alexandria in October 1986.)

A new application of the Omega navigation system is described in which a ground station is enabled to display multiple vehicle locations. Pulses from the vehicles are triggered by Omega signals and the times of arrival of the pulses at the ground station are processed to provide a ‘radar-like’ display of each vehicle's range and bearing.

This paper was presented at the eleventh Annual Meeting of the International Omega Association held in Quebec in August 1986.

This is a short summary of a paper which shows what a navigator can do to fix his position at sea using basic equipment (sextant, hand-held compass, almanac, four-figure mathematical tables) without the help of dead reckoning or the benefits of GMT.

This paper reports on a study conducted during the academic year 1985–6 by Assistant Professor H. Hagiwara of the University of Mercantile Marine in Tokyo and Professor J. A. Spaans of Delft University of Technology.

Present and future marine navigation requirements have been analysed recently for different categories of users. This paper relates to those navigation applications which need very high real-time accuracy, high availability and reliability of navigation information. This domain is mainly influenced by marine surveying and navigation community needs such as oil and mineral prospecting, hydrography and future prospecting of maritime economic zones, which are usually of high strategic or economic importance. The majority of identified needs for this limited community of users call for real-time accuracy and repeatability of instantaneous positioning ranging from 2 to 10 m, distances from shore up to 1500 km (water depth 300–1000 m), update rate of position information of a few seconds, and availability and reliability of position information data of 99 per cent or more. To reach such stringent requirements none of the existing means and even new satellites or Earth-based acoustic or radio aids individually can solve the problem. This leads to the necessity of combination or hybridization of several means which together may approach the solution.

Flight inspection is the means by which the performance of a navigation aid is measured to ensure that it is meeting the requirements of the operational procedures based upon it. It can involve laboratory-type measurements in an environment which is generally unstable and sometimes hostile. The first requirement is the position of the aircraft fixed to an accuracy commensurate with that implied by the operational specification of the navigational aid. A range of techniques for position fixing has been developed over the years. Where possible the technique should just meet the ‘one order better than’ criteria. The use of systems with accuracies significantly better will usually result in financial or logistic penalties.

Barring electronics and steady timekeepers the Moon's orbit provides the readiest means of finding Greenwich time at sea. But the Moon moves so slowly in her monthly circuit that an error of only 1′ in locating her will cause an error of nearly 2 minutes in GMT. Obviously the navigator needs some idea of how well he has pinpointed her. Even a modest error, unless suspected and allowed for, could be disastrous.

This paper was presented by W. Blanchard to a meeting of the Technical Committee on 25 March 1987. It has been forwarded to an IAIN Working Party set up to consider possible contributions to the ICAO Future Air Navigation Systems study.

Civil airways route structures are constructed around en-route and terminal navigation aids such as VOR, DME and ILS. Radio navaids do not always provide accurate information to aircraft and their performance can be seriously degraded by system drift, electronic interference and unrelated changes to the local environment such as man-made obstructions erected in the beam forming area. To ensure efficient and safe operation of air traffic control, ground-based aids must be commissioned and maintained to stringent specifications at all times. Consequently, regular airborne performance checks of all radio/radar navigation aids are essential, and since the most critical time of any flight is the approach and landing phase, the precision aids (PAR and ILS) are checked at regular intervals and with a greater positional accuracy than the general navigation aids.

Methods of calculating the course and the distance between two points from a knowledge of their latitudes and longitudes, or calculating the latitude and the longitude of the arrival point from the course and the distance from a known departure point, are called sailings. Middle-latitude sailing and Mercator sailing have been widely used.

Concerning the minimum fuel routeing, the algorithm stated in Section 2 is very effective in the calculation of the (sub)optimum route for most environmental conditions. However, when the weather around the great circle route is extremely severe and the final isochrone bends backwards sharply near the destination, there is a possibility that the route passing through the other side of the great circle causes less fuel consumption than the calculated minimum fuel route. In such a case, to investigate the fuel consumption of that alternative route it is necessary to apply the algorithm for only the other side of the great circle route.