the retrofit problem, it would be unconscionable to make a forced choice between these two approaches until thorough testing of both solutions have been completed. This process can be expected to take at least two years at the rate at which the government has been funding these studies.

When the preferred approach is determined, our engineers estimate that it will take at least three years from the time of delivery of the first kit to install a modification on our complete fleet, assuming that all air carrier airplanes were simultaneously modified. The cost to our industry of attempts to speed up this time span increases at an enormous rate and I would estimate that our costs would double if, for example, a two-year time period were required. For the same reason, a considerable reduction in cost would be possible if the time period were extended.

With regard to conclusion (2), the cost of retrofit, we estimate that to comply with these programs by January 1, 1978, which we believe to be the earliest achievable date, the cost to American Airlines would range from $120 to $315 million, depending on whether nacelle treatment or a new front fan approach is chosen. We believe these figures, expressed in 1972 dollars, are accurate to within plus or minus 20%. American Airlines cannot conceivably fund a program of this magnitude. The suggested alternative, which is to replace these airplanes by that date, is also unworkable. We would be required to retire ninetyseven 707-type aircraft. Even assuming that our route structure and traffic demand would permit replacement of the lift provided by these aircraft with DC-10's (which is not the case), we would have to purchase fifty-seven new DC-10's at a cost of approximately $1.1 billion. Faced with these staggering costs, which we believe are entirely realistic estimates, I cannot in any good conscience support a retrofit program of this nature, unless it is accompanied by an outright financial grant to make this modification in the public interest.

The foregoing explains the basis for our conclusion (3) that the proposed January 1, 1976 date is not feasible. If we were required to comply with FAR 36 by January 1, 1976, it would be impossible for us and other airlines to meet the public need for transportation and the requirements of our certificates of public convenience and necessity. Under such restrictions we could not provide service on a majority of the routes we are certificated to serve. While it is more difficult and time-consuming to modify some types of aircraft than others, the January 1, 1976 proposal is, in my opinion, impossible to achieve.

Regarding conclusion (4), we believe that strict compliance with FAR 36 by engine or nacelle retrofit may not be the most effective way to reduce noise. There are several promising options to reduction of noise level by altering take-off and approach procedures. We have already implemented new take-off and approach procedures which have reduced noise exposure, but considerably greater progress can be achieved, we believe, through our program of active testing, with support from NASA, of two-segment approach procedures. We believe it can already be established that noise relief of the magnitude you seek is possible by the use of this technique. This approach offers the best hope, in my opinion, of reasonably prompt relief in the Los Angeles

area.

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525-314 O-73-8

Noise abatement achieved by revised approach procedures could resolve a significant concern over another aspect of the retrofit proposal. Specifically, the difference between the current noise levels of certain aircraft (in our case the 727's) and the requirements of FAR 36 will be so minimal as to be almost imperceptible to the public. It would be a tragic waste of resources to effect this retrofit only to find that the public is wholly unsatisfied. Relief through modification of approach procedures may consequently offer a better solution than retrofit, both in terms of cost impact and more prompt conformity with FAR 36. This is certainly true with respect to the quieter of the older aircraft, such as the 727's, and might provide an acceptable solution to the problem of the 707 and DC-types as well.

Regarding our conclusion (5), the proposed requirement that new types of aircraft to be manufactured after January 1, 1975 comply with FAR 36 minus 15dB is in the opinion of our engineers totally unrealistic. Such a requirement would necessitate the use of a new engine vastly quieter than any now existing. It has been our experience that an absolute minimum of four years is required to develop such a new engine even when the technology is in hand to permit commitment to the project.

It is also worth pointing out that prohibiting operation to the United States of aircraft of foreign registry that do not comply with these noise levels would present a most difficult international problem for our country. Foreign governments could hardly be expected to permit U.S. carriers to serve their countries if the operation of their own flag carriers to the U.S. was prohibited. Sincerely,

Hon. JOHN V. TUNNEY,

GEORGE A. SPATER.

TRANS WORLD AIRLINES,

New York, N.Y., September 14, 1972.

U.S. Senate, Committee on Public Works,
Washington, D.C.

DEAR SENATOR TUNNEY: TWA is pleased to have this opportunity to respond to your letter query of September 8 on the control of aircraft noise.

As you knows perhaps, TWA has been instrumental and successful through the years in forcing the development of quieter and more pollution free aircraft. TWA, along with several other leading airlines, has always contractually required the incorporation of the latest noise attenuation technology that is practical and effective when procuring aircraft. This continues to be our policy and our objective. Current examples of good progress are the Boeing 747 and Lockheed 1011.

TWA has also studied the various programs and designs targeted toward the development of retrofit technology which have existed throughout the jet age. It is also familiar with current programs including the front fan and nacelle treatment programs mentioned in your letter. In fact, TWA just completed a comprehensive review of all known possibilities and programs last week.

Through the years, TWA has encouraged the development of those technologies which stand to reduce external aircraft noise. It was

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hoped that by now practical designs for effectively reducing noise from the older aircraft in our airport communities would be in hand. This is not the case and, unfortunately, little prospects for early practical solutions exist. However, all reasonable efforts to advance applicable technologies and to develop suitable designs should continue. As matters now stand, either the predicted noise improvements are so low as to be completely cost ineffective or they are impossibly expensive and would occur in a time frame that would not permit completion of retrofit programs prior to the 1977-1981 time period. This is too late since by then the majority of the older narrow bodied fourengine jets will either have been retired or will be on the eve of retirement from commercial service.

You may be interested to know that four-engine aircraft retrofit capital costs are estimated to run from approximately $1,200,000 per airplane for the quiet nacelle to approximately $1,900,000 per airplane for the new and as yet undeveloped front fan. Parts obsolescence costs, revenue loss from added fuel consumption and/or empty weight increases, and loss of utilization during the conversion period are all in addition and would total a very appreciable amount. The capital costs alone would result in a minimum increase in seat mile cost of from approximately 7.0% to 13%. Capital required for TWA aircraft alone. could total as much as $300 Million. This quite obviously would be totally unacceptable.

Costs and timing indicated herein are preliminary estimates since neither the quiet nacelles nor the new front fans are fully developed or have been tested in flight. The quiet nacelle being developed by Boeing Wichita will not fly until next year and the new front fan won't be in the air for several years and then only if engine ground tests are successful. It is of the greatest importance that such devices be tested for acceptability by human ears on a controlled empirical basis. History shows that meters and forecasted results simply are not reliable in this regard. In no event should retrofit programs or implementation schedules be adopted until this is done.

Thus, summarily, the suggested FAR 36 compliance date of January 1, 1976 for all aircraft operating into U.S. airports is totally unrealistic and cannot be achieved. At this time it is impossible to rationally set a date for the mandatory achievement of this objective. Applicable technologies must be advanced, noise reduction effectivity determined by flight tests and economic feasibility established first. Any language additions to S. 3342 along the lines suggested in your letter of September 8 are premature and ill advised.

As to the proposed requirement that new types of aircraft manufactured after January 1, 1975 comply with noise standards 15 EpnDB less than FAR 36 App. G., TWA understands this subject is currently being considered by the FAA. TWA doubts that the attainment of a 15 EpnDB reduction is realistic by then and suggests that a 5 to 8 EpnDB reduction would be more realistic. However, since action is under way, language additions to S. 3342 would seem unnecessary and duplicative.

TWA respectfully suggests that prior to the inclusion of any language in S. 3342 on aircraft noise alleviation requirements or retrofit schedules that an informal meeting be held between you and/or your

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staff and selected airline representatives. Such a meeting could serve to discuss and clarify significant facets of retrofit to a greater extent than is practical in this letter. If you consider such a meeting appropriate, TWA would, of course, be happy to participate.

Very truly yours,

F. C. WISER.

INSTITUTE OF NOISE CONTROL ENGINEERING,
Cambridge, Mass., September 18, 1972.

Senator JOHN V. TUNNEY,
New Senate Office Building,
Washington, D.C.

Attention: Mrs. Jane Frank

DEAR SENATOR TUNNEY: I am pleased to respond to your letter of 12 September 1972 in which you solicit my views in regard to the Noise Pollution Control Act (S. 3342). The comments offered herein are based on assessment of the status of aircraft acoustics technology and regulation available to me as a Member of the Aeronautics and Space Engineering Board of the National Academy of Engineering and upon jet engine and airport noise research in studies performed by me and my colleagues at Bolt Beranek and Newman Inc.

The current state of technology supports the addition of language to S. 3342 that, "No aircraft could land at U.S. airports after 1 January 1976, unless such aircraft complied with the maximum noise level standards in Appendix C of Part 36 of the Federal Aviation Regulation." However, the reqirement that new aircraft meet a noise level 15 EPNdB lower than the FAR Part 36 standard by 1 January 1975 is incompatible with development, manufacturing, and certification schedules and possibly beyond the state of art of noise-control technology for large transport aircraft. A careful look at available noise control technology and at the length of time it takes for manufacturing and certification schedules to be accomplished, convinces me that new aircraft could realistically be required to meet noise regulations that are 10 EPNdB lower than FAR Part 36 by 1 January 1978. In making this statement I have not balanced the technological and time schedule against economic considerations because I feel that this balance must be made by government and not by engineering people. A 15 EPNdB reduction below FAR Part 36 might be feasible by 1982, but further study is necessary to confirm this statement.

I strongly recommend that the Environmental Protection Agency be given the responsibility for specifying and enforcing noise exposure criteria for communities near airports. Although, the Federal Aviation Administration and the Department of Transportation along with NASA have supported technology development in this area, the FAA has shunned the responsibility for setting aircraft community noise exposure criteria. The EPA should be given the authority for selecting and enforcing these criteria, but the specific methods and individual aircraft numbers involved in meeting these goals should be selected in collaboration with NASA, which has responsibility for aeronautics research, and with the FAA, which has the ultimate responsibility for

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the refinement and application of aviation technology to the civil air transportation system.

If the Noise Pollution Control Act is still an issue during the next session of Congress, my colleagues in this country, in particular the NAE Board, INCE, and Bolt Beranek and Newman Inc. and other research companies would be pleased to provide you with detailed comments in regard to the present status of acoustical technology pertinent to the subject of aircraft retrofit and new aircraft development.

Sincerely,

LEO L. BERANEK,
President, INCE.

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