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This paper is the second chapter of a series on Air Navigation Systems during the fifty years from the early oceanic flights and the inception of commercial aviation to the introduction of INS in civil aircraft. These papers are intended as critical commentaries. A definitive history has yet to be written. The writer would be grateful to receive criticisms of the paper or comments on the subject.
Forty years ago Sir Harold Spencer Jones, Astronomer Royal, gave the first Presidential Address on the ‘Development of Navigation’ so it seems appropriate on this anniversary to address a related theme from a different perspective.
This paper is the first of a series on Air Navigation Systems during the fifty years from the early oceanic flights and the inception of commercial aviation to the introduction of INS in civil aircraft. These papers are intended as critical commentaries. A definitive history has yet to be written. The writer would be grateful to receive criticisms of the paper or comments on the subject.
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Whereas the proper object of all commercial transportation is profit-making, the navigational objectives of taxis and of airliners differ remarkably. In airlines navigation only affects product quality and operating costs but in taxis the revenue (the fare on the meter) is a function of the navigation. Regularity of service is meaningless to taxis whereas regularity of schedule keeping is an imperative of airline navigation because it is only possible to offer air fares a full order lower than taxi fares on aeroplanes costing up to $200,000 a seat by achieving high equipment utilization. Many taxi drivers hire their cabs at a weekly rate which includes maintenance and repair but not fuel. They therefore have a direct interest in the cost of fuel but not in wear and tear of machinery. Finally, taxi drivers are self-employed businessman whose income depends entirely on their navigational skills.
Whatever the word ‘navigation’ is taken to mean, it must, etymologically, be something one does to a ship. What a pity that the name ‘airship’ was given so early in the evolution of aviation to its dinosaurs! The modern airliner is truly a ship of the air. There was a move, half a century ago, to coin the word ‘avigation’ but, apart from the obvious retort that, if ‘navigation’ is of ships, ‘avigation’ is strictly for the birds, the term ‘air navigation’ had already been established by the International Convention on Air Navigation and the Air Navigation Acts by which Parliament legislates on aviation in general and its commercial application in particular.
An announcement of Wing Commander Anderson's recent death appears on another page. Mr William's spirited criticism of Anderson's ‘Rotations in Navigation’, and by implication his more recent note on Coriolis (May 1983 issue), was of course written before the sad news was known. It is published here without modification (and in spite of the author's offer to withdraw it) as would undoubtedly have been Wing Commander Anderson's wish.At the end of the last war Wing Commander E. W. Anderson was one of the most distinguished practising navigators in the Royal Air Force. ‘Andy’, as he is known to so many, has since become navigation's leading exegete through his work in this Institute, his articles, lectures and books. ‘Rotations in Navigation’, however, has got him in a flat spin. The reason why has wider implications worth examining.Andy starts by suggesting that the difficulty of explaining Coriolis ‘may be due to the intellectual danger of trusting mathematics without making sure that the right circumstances surround the formulae which emerge’. This observation illustrates how well one can write English without saying what one means. Circumstances, right or wrong, cannot surround a formula although the statement a formula makes may be irrelevant to our circumstances. It is precisely because pure mathematics is the language, as Russell put it, ‘in which we do not know what we are talking about or care whether what we say about it is true’, that applied mathematics is the language in which we are obliged to say what we mean or be seen to use the language wrongly.
Having been concerned in the mid-fifties with developing the general equations of most economic flight and applying them to the profitability of an airline, I was surprised to discover when I was a ship financier in the early seventies that the much simpler equivalent marine problem had never been addressed by our clients, nor did the question arise apparently in the negotiation of their time charters with oil companies which are not conspicuously unsophisticated in some matters. I was therefore most interested to read Captain P. M. Alderton's paper on ‘The optimum speed of ships’, this Journal, 34, p. 341. If it were not for his charming reference to Napier's paper on the same theme dated 1865 one would be tempted to think that this was a case where the air leads the sea by decades.
I am reminded that this was the title of a paper by Professor W. M. Smart, published elsewhere in 1946, dealing with the rhumb line on the spheroid, by references in recent issues of this Journal to a paper of mine entitled ‘Loxodro-mic distances on the Terrestrial Spheroid’ which appeared in this Journal 32 years ago: the subject crops up every few years.
If Turner is right that ‘the underlying theory of the traditional approach (to rhumb-line sailing) is obscure’ and that there is a ‘lack of ready availability of a table of distances of parallels of latitude from the equator, it is certainly not the fault of this Journal which precisely 20 years earlier published a paper which gave: 1. The correct mathematical theory of rhumb-line sailing on an oblate spheroid. 2. The name ‘meridional distance’ to what Turner now calls the L(φ) function. 3. A table to reduce latitude to meridional distance. 4. A rule of thumb procedure to calculate rhumb-line distances correctly with no more labour than that which has always been used to do it wrongly. 5. A method (with table) for use on the spheroid when the track angle is nearly 90° and the method Turner discusses is impracticable. 6. A survey of methods and tables then current.
‘Navigation demonstrateth how, by the shortest good way, by the aptest direction, and in the shortest time a sufficient ship between any two places may be conducted.’ To our Elizabethan forebears it was evident that the best way to conduct a ship was by the shortest passage of time which engendered least risk of catastrophe and avoided excessive wear and tear on ship, equipment and possibly passengers and crew. In the age of value-engineering and cost-effectiveness we are required to quantify these conflicting criteria. This is a matter of economics, which is concerned with applying the finite resources of mankind to the satisfaction of its infinite wants.
S.S.T. Costs - Cost Analysis of Supersonic Transport in Airline Operation, Volume 1, Research Analysis Corporation, paper, 156 pages, 36 figures, 10½ × 7¾ in., Research Analysis Corporation, 1966, No price stated. - Volume 21 Issue 4
For a quarter of a century now we have struggled in a curiously impotent way with the problem of long-range navigation of civil aircraft and the associated problem of control of traffic in oceanic control areas. The deliberations of technical conferences of the International Air Transport Association alone during the past 15 years on the subject of Long-range Navigation of Civil Aircraft would fill a library.The development of navigation has always been retarded by difficulties with the analysis of the operational requirement. It is, for example, inconceivable that if the operational requirement for astronomical navigation had been properly explained to eighteenth-century astronomers, they would have waited for practising seamen to invent the position line almost by accident. As neither the authors of Long-range Navigation of Civil Aircraft (D. E. Hampton and J. R. Mills. This Journal 17, 183) nor any of the speakers recorded in the subsequent discussion are directly involved with the operation of aircraft some remarks on the assumed requirements may be helpful.
During the first years of the last war the navigational problem was how to get to the target at all. In such conditions solutions to the navigation problem are priceless. Towards the end of the war it came to be accepted that, in transport operations at least, guidance to destination was almost a matter of course. Navigational performance ceased to be regarded as a question of success or failure and became a question of efficiency. This development in air transport we owed most of all to the radio compass.As the volume of civil traffic grew, it rapidly became clear that the major limitation on navigational efficiency of air transportation was (and it still is) air traffic control. Although there has been considerable interest in the optimum trajectory particularly in connection with turbine aircraft, the development of refined operating techniques has been damped by restrictions on their application by A.T.C. The flat assertion by some would-be supersonic aircraft manufacturers that the supersonic (unlike the subsonic) jet will not take NO for an answer from A.T.C. once it is committed to a flight programme has recently been a most valuable stimulus.The A.T.C. problem is well known. It is generally accepted that the capacity of an air space depends on the quality of navigational data, of the data link between aircraft and control centre and of the data correlation capabilities of the centre.
In areas of sufficiently high traffic density, air traffic control in some form will always be the primary mode of ensuring aircraft separation. Any traffic control system is concerned with separating aircraft in the future; therefore, the nominal separation criteria are determined by the accuracy of prediction of future movement of the aircraft and by the ability of the control system to correlate flight path predictions. The utilization of an airspace of a given capacity is determined by the distribution or flow of traffic.The accuracy of prediction depends on track-keeping and maintenance of planned ground speed. Since improvements in track-keeping will be limited for some time by past I.C.A.O. decisions on short-range navigation aids, attention is directed in this paper to maintenance of flight-planned ground speed. The effect of this on the operating cost of a modern jet airliner is examined and compared with the cost of flying at minimum cost mach number at a less than optimum altitude. It is concluded that in a crowded airspace, speed maintenance is preferable in short-range operations.The increase in space utilization by flow control is illustrated for a simple model, showing that speed control by A.T.C. increases utilization of a space capacity, which has already been increased by speed maintenance.
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