The Institute has now completed two years of its existence. The papers which have been read before it during these two years have covered a wide range of subjects and have served to emphasize the many ramifications of the science of navigation. Because of the high speed of modern aircraft, air navigation presents more problems and of greater variety than surface navigation, but even on the problems of surface navigation there has been ample scope for a wide range of discussion. The Institute has taken a prominent part in the discussion of the proposals for the revision of the Abridged Nautical Almanac. It might with some reason have been supposed that there was nothing more to be said on the methods of reducing astro-sights and determining position at sea. The problem is perfectly straightforward and there is a limit to the number of different ways in which the spherical triangle can be solved. But the essential basic data can be presented in a variety of ways, while there are many possible methods of presenting tables for the solution of the spherical triangle. The decision to use Greenwich hour angle instead of right ascension in the Abridged Nautical Almanac has followed its adoption in the Air Almanac; the revised Almanac will have an entirely different format from the present, while the methods of reducing sights must be correspondingly modified.

The effect of radar on the application of the Rule of the Road at Sea has been given attention in several papers and discussions in recent months. Deductions on their relationship have been attempted, and already judgements have been delivered in the courts of this and other countries which take account of the installation of radar in one or both of the parties to a collision. The suggestion has been seen that guidance to mariners concerning their actions and responsibilities when radar is fitted must await the development of case law. This development will be a lengthy and probably painful process and the object of this paper is to discuss the possibility of establishing principles which would enable the great potential value and legitimate application of radar to be established without waiting for casualties.

Practical experience in radar-assisted marine navigation has shown that the closer one is to the general land areas, navigational seamarks, &c, the easier position fixing from radar information becomes, although some particularly congested and confined waters provide exceptions to this rule. There are usually large numbers of more suitable targets available at the closer ranges, and increased ease of identification results from objects being closer to the observer. The latter effect, of course, arises from initially knowing one's position more accurately, and this in turn is based on the shorter ranges at which bearings and/or ranges are being taken.

This paper deals with the improvement to be gained by using position lines from two Decca chains to obtain a fix in areas where a single chain fix is liable to extensive errors.

Recently The Decca Navigator Company, with the cooperation of the Admiralty, undertook a series of trials between Scotland and southern Norway, using the English and Danish chains of stations outside the normally used coverage of either chain. The results obtained were highly satisfactory and an account of them is given in this paper.

As between the scholar and the technician, the armchair theorist and the practical man, the antagonism is as old as civilization itself. In Queen Elizabeth's days the gentleman born was the only gentleman, however ignorant, while learning was the preserve of the universities; the practical man was a mere ‘mechanician’. But there was some liberal thinking, common-sense thinking, even in those days, and one Gabriel Harvey, a well-known literary man and controversialist, spoke up boldly for the technicians. Even though they had heard no university lectures, he said, and were deficient in book-learning, it would be a bold man who would despise such expert practitioners as Humfrey Cole, the mathematical instrument maker, William Bourne, the naval gunner, Matthew Baker, the shipwright, John Shute, the architect, John Hester, the chemist, and Robert Norman, the hydrographer and compass maker. No fewer than four out of the six notable men he named were doing work that was relevant to the advancement of the navy and navigation. They were at the height of their powers in the decade preceding the defeat of the Spanish Armada, a coincidence which cannot be without significance.

This paper describes tests of an approach procedure in which aircraft approach the airport on a radial track, circle the airport on an orbit and finally approach to land on another radial track in line with the runway. Ninety-six approaches were made with a representative selection of airline pilots in an aircraft fitted with the Australian Distance Measuring and Multiple Track Range Equipment.

The flight tests provide information as to the accuracy with which pilots can follow a set track, both for track accuracy and turning, when provided with adequate navigation aids. The average time for the particular procedure used was 18 minutes, and 90% of all times were within ±1 minute of the average. Maximum departures from the correct track occurred during orbiting where the average track was 0·2 mile inside the nominal orbit, and in 90% of approaches the departure did not exceed ±0·8 mile. Detailed analysis of the turns is also given in which it is shown that, on the average, turns occupy ¾ minute instead of the ½ minute required for a correctly executed Rate 1 turn.

The history of mechanical transport has been one of increasing speeds and there seems to be little doubt that air transport will follow this pattern. To the passenger, increased speeds mean a saving of time, and time is money. To the operator, increased speeds mean more flights per week and therefore greater earning capacity for his aircraft. This year indeed has been marked by the appearance of the four-jet air liner, the forerunner of the four hundred knot air transport.

The necessity for an accurate instrument to indicate the height of an aircraft above the ground over which it is flying at any instant has long been recognized and a variety of types have been suggested.