CIVIL AVIATION (SONIC BOOM PROBLEMS) (Hansard, 3 February 1967)

§ Mr. Edwin Brooks (Bebington)

It is fitting to end a week which has seen nuclear bangs outlawed in outer space, with some thoughts about the bangs we seem doomed to hear before long within the earth's atmosphere. I say "doomed," which may sound fatalistic, because I am aware of the vast pressure of technology speaking in the name of progress. But if the needs of the machine in the process distort human values, we have only ourselves to blame.

This afternoon I want to try, in the limited time available, to voice the values and needs of the millions of ordinary human beings whose peace of mind—quite literally—is at stake in the supersonic future.

I hope I am not a reactionary, or an enemy of progress. But I am bound to say that the tiresome cliché, "You can't stop progress", not only exonerates every abuse and perversion of science but fails to grasp that our decisions involve a determination of priorities, a balancing of alternatives, and a judgment sometimes of conflicting values.

Of course the image of a supersonic—indeed hypersonic—age is breathtaking, exciting and adventurous. Man will outpace the wings of the morning, and journey to the Antipodes and back before lunch. I would not deny this vision, of man soaring ceaselessly into the unknown, its power to capture our imagination and tease our intellect. It is a vision both of beauty and of power, both never more eloquently captured than in the functional perfection of the Concord airliner.

But if it is a vision, neither is it yet anything more. For all the glamour of the publicity photographs, for all its bewildering complexity, the SST—the supersonic transport—is still in the age of the silent film. It has yet to have the sound track added. And it is the fear of many, including notable aeronautical experts, that when the sound track is added it will prove to be like an old-fashioned Western shown on Cinerama— 1011 an endless fusillade of shots in all their stereophonic and supersonic intensity.

But the problem, if I may pursue the metaphor for a moment, is not simply one of producing a multi-million pound epic—and Concord is surely that—and then adding the sound effects hopefully. The problem is that we do not know—or do not appear to know as yet—whether the audience will be able to see the show through. We do not know whether the £500 million and more to be spent on developing Concord, nor the far greater costs envisaged by Boeing, will produce planes which will be permitted to fly on more than a small fraction of potential world airline routes. And the extraordinary thing is that the British Government seem broadly content to go on reading the tea leaves, instead of conducting a thorough series of field tests particularly, but not only, over our cities, for a period sufficient to evaluate the long-term civilian impact of the S.S.Ts. For some months I have been trying, with other hon. Members, to probe the Government's intentions. On 5th December last I was informed by my hon. Friend's predecessor that the evidence available suggests: that there are unlikely to be long-term physical and psychological effects upon people of sonic bangs of the intensity and periodicity likely to be associated with supersonic civil airliner fleets of the next decade. Although the Minister also said that he was considering whether it is necessary to carry out a series of sonic bang tests".—[OFFICIAL REPORT, 5th December, 1966; Vol. 737, c. 220.] I am bound to say that I found his reassurances complacent. Although useful information has doubtless been gathered from laboratory studies, or field tests with simulated sonic bangs, the only prolonged tests which have recognised the nature of the problem of sustained exposure among the general population were those conducted in Oklahoma City in 1964.

The question we must ask, therefore, is whether the Oklahoma evidence was so conclusive that comparable tests in Britain can be seen to be unnecessary. One reply to this question was given by the noble Lord the Minister of Defence for the Royal Air Force on 3rd August 1966. He stated in reply to a Question that: 1012 Reports on the sonic bang tests carried out by the Federal Aviation Agency in the Oklahoma City area in 1964 have been studied with great care. As the Federal Aviation Agency has pointed out in the final report, the results were largely inconclusive. Later in that same exchange he reaffirmed that The Oklahoma Study itself, in its final words, comes to no conclusion other than that the study was of lasting interest".—[OFFICIAL REPORT, House of Lords, 3rd August 1966, Vol. 276, cc. 1303–05.] Now what were these results, of lasting interest but largely inconclusive, based upon? The Oklahoma tests lasted six months, with up to 8 supersonic flights a day occurring at prescribed times. No flights were made at night throughout the whole period, yet Professor E. J. Richards, Director of the Institute of Sound and Vibration Research at the University of Southampton, pointed out in the Science Journal in May, 1965, that for economic reasons the SSTs will fly intensively at night. He went on to suggest—surely not unreasonably—that night flights would produce a higher rate of complaints, and for this reason alone it would seem that Oklahoma has grossly minimised the problem.

Again, the ordered timing of the flights occuring at regular intervals in Oklahoma might minimise the problem in reality. Bangs which come laterally out of the blue are more disturbing than those used to check one's watch.

But, even after making such reservations about Oklahoma, it is significant that the rate of complaints reported, after the initial peak of complaints, settled down to a broadly regular plateau on the graph at about 250 a week, fluctuating between 200 and 500 per week during a period of nearly five months. Even accepting that the early complaints included many bogus and frivolous ones connected with claims for compensation, it is disquieting that the rate did not significantly fluctuate over such a long period. More to the point perhaps, the proportion of people who said they expected they would get used to the bangs fell from 90 per cent. in the first 11 weeks to 73 per cent. in the last 7.

After six months of what we are bound to call minimal exposure in terms of the 1013 real thing, a quarter of the population and more had come to view the future with apprehension, and the apprehension actually grew during the tests. Oklahoma, I suggest, gives us naught for our comfort. And those who discount American experience because, say, British buildings are of different construction, or our temperament is different, place upon themselves the onus of establishing whether British cities and the British population will react more or less favourably than Oklahoma. At the moment, I regret to say, we seem better at speculation than calculation and experimentation.

I mentioned buildings a moment ago, and this point illustrates one of the many variables which make generalisation on the basis of a few simple tests—the odd daily tests, say—thoroughly misleading.

Professor Richards states: to an observer indoors the apparent loudness of the boom depends as much on the characteristics of the room as it does on the outside amplitude. It seems that the apparent loudness of a boom in, as he delicately puts it "the smallest room in the house can be as much as 12 decibels higher than in a large well-carpeted lounge. This difference may not sound much, but it equals a fourfold increase in pressure jump.

One shudders to visualise the consequences for someone of nervous disposition, inadvertently positioned in the smallest room, at the moment of an unexpected and notably more intense bang from the heavens.

There is also a good deal of evidence showing that atmospheric conditions of humidity, wind turbulence, and so on, can produce dramatic variations in our experience of sonic boom. Dr. Bo Lundberg, head of the Swedish Aeronautical Research Institute, has said: A rough measure is that one boom in a thousand, at every spot within the boom carpet, will be twice as strong or more than the average along the flight path. Since the average boom intensity of the SST at 60,000 ft. is roughly 1.5 pounds per sq. ft., there will be one in a thousand superbooms of 3 pounds per sq. ft. This might sound a slight risk until one does the sums.

1014 Between Los Angeles and New York, for example, Dr. Lundberg has calculated that 15 return flights daily will produce 100 million people exposures to superboom exceeding 3 pounds per sq. ft. in the course of a year. This is a large total of human cost for the price of supersonic travel for the privileged few.

Let those who are comforted by official soothing sounds note the growing uncertainty at the Ministry of Aviation, as revealed by successive witnesses to the Public Accounts Committee. On 18th February, 1965, in reply to questions about sonic boom and toleration levels, Sir Richard Way stated: We hope to have a very much clearer idea of this problem within two years. Such hopes were to be dashed. Nearly 18 months later, on 23rd June, 1966, Sir Richard Clarke, specifically when pressed on his predecessor's statement said: I doubt whether we shall have a clear statement of this situation for a very long time because this is a difficult issue. I would suggest that this is not only a difficult issue, but one which these distinguished witnesses have indicated is of growing difficulty and uncertainty. Is not this growing uncertainty about toleration levels the prime cause of the airlines' reluctance to commit themselves to large-scale orders for supersonic airliners? Since the economics of the SST must depend intimately upon the proportion of its flight conducted at subsonic speeds, the need to clarify toleration levels is critical to the whole future of this immensely expensive undertaking.

Those who support this undertaking must surely wish to remove this uncertainty at the earliest possible moment, if only to ensure that the market for Concord is not handicapped by possibly spurious allegations of its harmful effects. If the truth is that the sonic problem makes SST.s effectively uneconomic, it is equally better to find out now before the production orders are placed. My own guess—and it is only a guess—is that the sonic problem is far greater than we are prone to think. In so much of the public discussion there seems an assumption that the planes will simply fly to and from British airports.

We are therefore quite readily comforted when told that the SST will not 1015 fly supersonic until it reaches the oceanic section of its route. But what about those Atlantic routes linked to north-western and central Europe?

Many of the flight paths from such cities as Paris, Bonn, Cologne, Frankfurt, Copenhagen and Stockholm, will lie across Britain, and it is optimistic to assume that the SST operators plying such routes will forgo their supersonic potential except over the Atlantic. It is small wonder that individuals and organisations are voicing fears.

I have here a letter from the National Farmers' Union, which is particularly concerned about the effect of boom upon farm animals, including embryonic development, for example, in poultry. I would like to quote one sentence from this letter where it states: We are concerned not simply with the possible deleterious effects on farm stock, on glasshouses, farm buildings and dwelling houses, but more generally upon the whole quality of life in the countryside; and our fear is that the development of the Concord and the pressure of economic forces, may encourage the Government to allow flights at supersonic speeds in circumstances which would make booms audible over a wide area. In the New Scientist, dated 26th January last, is a report that Mr. Stewart Udall, U.S. Secretary of the Interior, referred to damage to prehistoric cliff dwellings caused by landslides set off by sonic booms from military aircraft. Since last August in one area the sound barrier has been broken 83 times in the Canyon del Muerto area and park service engineers estimate that 80 tons of rock have fallen as a consequence upon the cliff dwellings. One ton of rock collapses for every sonic boom.

Time forbids my catalogue of alarming events—there are many more, if time permitted, and I simply make the final point that, for the past decade or so, supersonic flights by military aircraft have been forbidden over these islands except in exceptional circumstances. Nothing I have read on this matter leads me to think that this decison was, and remains, other than a wise one.

Every new transport medium has its own specific problems. In the case of the railways, Britain was careful to regulate their development in the interests of the wider community. In the case of the 1016 motor vehicle, events now suggest a lack of adequate anticipation of the consequential problems. Today, we are on the threshold of a revolutionary new concept in flying, one with undoubted advantages, yet with equally obvious and alarming hazards.

The time has come to draw up a balance sheet, before we find ourselves inadvertently committed to a machine which could irretrievably damage and devalue that all-pervading natural environment, the sky above us.

I ask the Government to embark upon a properly conducted series of researches which will elucidate the tolerability of sonic boom. I would ask, too, that no production orders for the Concord be placed until the results of such tests are available and prove reassuring.

§ The Minister of Aviation (Mr. John Stonehouse)

The House will he grateful to my hon. Friend the Member for Bebington (Mr. Brooks) for initiating this debate, and I congratulate him on the research he has done into the subject. It raises a great many questions, and I shall follow some of the points which my hon. Friend made. First, may I make the general point—I think that my hon. Friend himself implied it—that every new invention produces a nuisance for somebody. There are in my constituency steam hammers which are absolutely essential to our industrial life in Britain, but they make an intolerable amount of noise for my constituents. As my hon. Friend said, the motor car produces a great many problems and, indeed, it can produce a great deal of noise. The development of civil aircraft, particularly jet aeroplanes, created a great many problems in connection with the control of the noise produced.

In each of these cases, there had to be a balance cast between the value to the community of the development and the disadvantages to the community of the noise and nuisance created.

I agree that it is important to have a proper evaluation of the position regarding the sonic boom as this new form of transport is developed. Perhaps I might explain what the sonic bang is. It is different from the usual noise made by aircraft. It is a noise produced when the aircraft reaches supersonic speeds 1017 about 100 miles after take-off. The aircraft continue to make this noise, the sonic bang, while it is flying at supersonic speeds, and, according to the height at which it is flying, it produces a band of bangs across the countryside or the sea about 15 to 20 miles a side. It is, therefore, a continuous noise affecting the ground below.

It has been demonstrated abroad that the amount of noise and nuisance created by these bangs is generally tolerable to the community. There are, of course, many complaints made both in the United States and in France when sonic bangs are caused, but it has been generally shown that the majority of the community can accept these bangs, although there is a minority which can be very vociferous in its complaints.

This question is related to the nuisance which is caused rather than to the damage caused. I think that apart from the possibility of damage to structurally unsound buildings, there is no real likelihood of damage or loss being caused on the ground as a result of sonic bangs such as are likely to be caused by the Concord. The problem arises because of the nuisance of the noise.

I agree very much with the point made by my hon. Friend about the special problem caused by bangs made at night. Researches show that airlines can make economic use of supersonic transports by flying them during the day, and there may not be very much attraction to the customers of the airlines, who would, perhaps, pay a slightly higher fare than for the normal subsonic aircraft, to fly supersonically at night.

We have had one test in Britain, which was held in 1965 at R.A.F. Upwood. A number of hon. Members attended that test, when a comparatively small number of bangs were made. I believe that most of those who attended, as I did, will agree that the nuisance caused, at least by that test, indicates that there is no evidence yet that these sonic bangs would be intolerable. I agree, however, that before we can make a final assessment, it will be necessary to have a more complete evaluation, particularly by tests conducted over cities.

The Government are considering precisely that proposal. We have to minimise the inconvenience that might be caused, but it would, of course, be at 1018 some inconvenience and cost to the community if these tests were conducted. We would want not only to determine the Government's views on supersonic flying by the Concord, but, as my hon. Friend correctly pointed out, we have to determine our attitude to supersonic flying by other countries over the United Kingdom.

Other countries will, we hope, be acquiring the Concord, and if the American S.S.T. is developed that will be acquired also. Operators of these machines will want to have rights to fly supersonically across the United Kingdom and we have to consider whether we should grant those rights to them.

We must also consider the economic viability of the Concord project if supersonic flight over land is disallowed. If there is a complete ban on supersonic flights over land, the market for the Concord would be reduced to between 55 and 65 per cent. of what we now expect it to be if there is no ban. If there is a partial ban and supersonic flight is allowed over part of the land, the market will be reduced to 75 per cent. of what we now expect the demand to be. A complete ban would not, therefore, make the project completely uneconomic. It would simply reduce the market and the demand for supersonic transports if there were a ban over a large land mass such as, for instance, the United States. That would cut out the possibility of the SST flying across the United States of American.

The Government must, therefore, at some stage consider, on both these grounds—the question of overflying the United Kingdom and the viability of Concord—their position in relation to the sonic bang and its acceptability.

We have at our disposal the results of the tests which have been carried out in the United States. As my hon. Friend has said, there has been a six-month series of tests in Oklahoma which produced a lot of helpful material, although the results were not conclusive. We have to consider whether the attitude of the people in a typical town in the United Kingdom would be different from that of the United States. This is a factor which has got to be borne in mind as we consider whether or not we should take steps to conduct these tests here.

1019 As far as military flying is concerned, it is correct, of course, that we do ban supersonic flying by the Royal Air Force as a general rule in the United Kingdom, but a special point to bear in mind about military flying is that much of this is producing a bang which is greater in intensity than that expected to be caused by the Concord.

My hon. Friend made a reference to orders being received for Concord. I should like to point out to him that a large number of airlines, including airlines in the United States, have given orders to the manufacturers for Concord, and, therefore, they are firmly expecting this aircraft to be a viable proposition as far as they are concerned. The total number of orders and options received is, so far, 69, which, considering that the aircraft is not flying yet, is an extremely satisfactory position.

1020 The development of Concord is going very well. It will be flying next spring from Toulouse, and we will have an aircraft flying from Bristol towards the end of next year. This means that this problem of sonic bang is one about which decisions will soon have to be reached.

I can assure my hon. Friend and the House that the Government take a very serious view of all the points he has raised. We agree with him that it is necessary to establish a balance sheet here. This is what we aim to do in due course. We take a serious view of this, and every point he has made in this debate will be developed in our evaluation of the question whether or not tests should be held in Britain.