EPA 550/9-76-013
NOISE STANDARDS
FOR
AIRCRAFT TYPE CERTIFICATION
(MODIFICATIONS TO FAR PART 36)
AUGUST 1976
U.S. Environmental Protection Agency
Washington, D.C. 20460
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SUMMARY
Federal Aviation Regulations Part 36 (FAR 36) was the first type
certification regulation for aircraft noise prescribed by any nation.
It is a comprehensive rule containing highly technical appendixes whose
purposes are to require the maximum feasible use of noise control
technology, to set standards for the acquisition of noise levels, and to
obtain data useful for predicting the noise impact in airport neighbor-
hood communities. Since the promulgation of FAR 36 in 1969, noise
control technology has advanced substantially, the significance of com-
munity noise impact is much better understood, and the techniques and
equipment for data acquisition and reduction have improved consid-
erably. It is appropriate, therefore, to consider amendments to FAR
36 with the objective of strengthening and extending the original pur-
poses, and, in particular, to close any loopholes that may exist.
In the following, the analyses in Section 5 examine every section
of the technical appendixes and provide recommendations for
changes where appropriate. The final recommendation is that two
NPRMs be proposed, each independent of the other, containing a total
of 24 amendments. The first NPRM would be concerned primarily
with the compliance noise levels and the airplane flight procedures.
The second NPRM would be concerned primarily with the methodology
for the noise measurement and evaluation procedures. The reason for
the development of two separate NPRMs is to avoid as much as pos-
sible any controversies whereby one would delay implementation of the
other.
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Compliance noise levels were developed to represent three time-
dependent noise control options identified as current, available, and
future technology. Levels pertaining to current technology would be
implemented immediately, available technology in 1980, and future tech-
nology in 1985. The latter requirements are best estimates at this
time for the lowest noise limits below which it is impractical or even
impossible to proceed.
The health and welfare and cost considerations in Section 6 exa-
mines two individual single runway airports (air carrier and general
aviation) as indicators of the noise impact resulting from the imple-
mentation of various options for compliance noise levels. Rectangles
enclosing the runways, whose dimensions are compatible with the
FAR 36 measuring points, can be considered as indicators of the
minimum land areas that suffer substantial noise impact. The areas
of the rectangles (roughly 3 and 2 square miles for air carrier and
general aviation runways, respectively) are examined for the noise
contours, in terms of the day-night level (Ldn), that lie within them.
The smaller the value of the contour completely enclosed by the rec-
tangle, the more effective will be the related compliance noise level
option in protecting the public health and welfare.
The areas enclosed by the rectangles should be devoid of single
family residences and should be under the control of the airport au-
thority or be controlled by the local political jurisdictions. In many
cases, most, if not all, of the enclosed areas will be airport
property and the ultimate objective would be to have the Ldn 55 contour
(EPA long range goal) to lie within the airport property fence. The
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indicator rectangles serve the purpose of providing a standard fence
which permits the effectiveness of the compliance noise level options
to be examined in a single and consistent manner.
The analysis for air carrier airports shows that compliance with
any of the options, even the future technology noise levels, would not
result in Ldn 55 contours lying within the 3 square mile rectangle
without severe restrictions on the number of aircraft operations. The
conclusion is that some compromise would have to be made. Either
a goal of Ldn 60 or even Ldn 65 should be accepted as adequately
stringent for those airports instead of Ldn 55, or noise compatible
land use should be directed to areas greater than 3 square miles.
The analysis for general aviation airports shows that compliance
with the future technology noise levels could be met without unduly
severe limitations on the number of operations. For these airports,
most of which are situated in suburban or rural locations, the Ldn
55 goal is probably not too stringent.
It is estimated that abuse of existing procedures for noise
measurement and analysis can result in a 3 to 4 dB noise exposure
disbenefit to the public. Therefore, the recommended modifications
to those procedures would provide benefits to the noise exposed public
by ensuring that the soui»ce noise reductions actually would comply
with the noise level requirements.
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TABLE OF CONTENTS
Section. Page
1. Introduction and Perspectives 1-1
2. Systems Control of Aircraft Noise 2-1
3. Background of Existing Aircraft Noise Regulations 3-1
4. Objective 4-1
5. Analyses 5-1
A. Technology Options and Applications for 5-1
Source Noise Control
B. Technology Standards of FAR 36 5-5
C. Noise Certification Test and 5A-1
Measurement Conditions (§A36.1 of FAR 36)
D. Measurement of Aircraft Noise Received 5A-13
on the Ground (§A36. 2 of FAR 36)
E. Reporting and Correcting Msasured Data 5A-35
(§A36.3 of FAR 36)
F. Symbols and Units (§A36.4 of FAR 36) 5A-43
G. Atmospheric Attenuation of Sound (§A36. 5 of FAR 36) 5A-44
H. Detailed Correction Procedures (§A36. 6 of FAR 36) 5A-46
I. General (§B36.1 of FAR 36) 5B-1
J. Perceived Noise Level (§B36. 2 of FAR 36) 5B-4
K. Correction for Spectral Irregularities 5B-6
(§B36.3 of FAR 36)
L. Maximum Tone Corrected Perceived Noise Level 5B-9
(§B36.4 of FAR 36)
M. Duration Correction (§B36. 5 of FAR 36) 5B-10
N. Effective Perceived Noise Level (§B36.6 of FAR 36) 5B-13
O. Mathematical Formulation of the Noy Table 5B-14
(§B36.7 of FAR 36)
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TABLE OF CONTENTS (Cont'd)
Section Page
P. Noise Measurement and Evaluation (§C36.1 of FAR 36) 5C-1
Q. Noise Measuring Points (§C36. 3 of FAR 36) 5C-3
R. Noise Levels (§C36. 5 of FAR 36) 5C-9
S. Takeoff Test Conditions (§C36. 7 of FAR 36) 5C-51
T. Approach Test Conditions (§C36. 9 of FAR 36) 5C-59
6. Health and Welfare and Cost Considerations 6-1
A. General 6-1
B. Indicators of Noise Impact 6-8
C. Costs 6-12
7. Conclusions and Recommendations 7-1
8. References and Bibliography 8-1
9. Figures 9-1
10. Tables 10-1
VI
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LIST OF FIGURES
Figure
1. Comparison of ISO and ICAO Proposals for 9-1
Temperature and Relative Humidity Test
Conditions.
2. Compliance Noise Levels Proposed by FAA. 9-2
(a) Sideline at 0. 25 Nautical Mile (463 Meters)
(b) Takeoff at 3. 5 Nautical Miles (6482 Meters)
(c) Approach at 1. 0 Nautical Mile (1852 Meters)
3. Compliance Noise Levels Proposed by ICAO. 9-5
(a) Sideline at 450 Meters (0. 24 Nautical Mile)
(b) Takeoff at 6500 Meters (3. 51 Nautical Miles)
(c) Approach at 2000 Meters (1. 08 Nautical Miles)
4. Airplane Noise Levels Compared to FAA and ICAO 9-8
Recommendations.
(a) Sideline: 2 Engines
(b) Sideline: 3 Engines
(c) Sideline: 4 Engines
(d) Takeoff: 2 Engines
(e) Takeoff: 3 Engines
(f) Takeoff: 4 Engines
(g) Approach: 2, 3, and 4 Engines
5. Noise Levels vs. Weight for Current Technology 9-15
Existing Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
6. Comparison of FAA Levels with Mean Levels 9-18
of Current Technology Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
7. Comparison of ICAO Levels with Mean Levels 9-21
of Current Technology Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
8. Modified Mean Noise Levels for Current 9-24
Technology Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
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LISTJ3FJFIGURES (Cont'd)
Figure Pag£
9. Modified Mean -3dB Noise Levels for Available 9-27
Technology Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
10. Propulsion vs. Weight for Current 9-30
Technology Airplanes.
(a) Maximum Thrust
(b) Max. Thrust/Max. Weight Ratio
11. Noise Levels vs. Thrust for Current Technology 9-32
Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
12. Noise Levels vs. Number of Engines for Current 9-35
Technology Airplanes.
(a) Normalized for Weight
(b) Normalized for Thrust
13. Thrust/Weight Ratio vs. Number of Engines for Current 9-37
Technology Airplanes.
14. Nonpropulsive Approach Noise for Typical Airplanes. 9-38
15. Nonpropulsive Noise Floor for Aerodynamically Clean 9-39
Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
16. Compliance Noise Levels for Available and Future 9-42
Technology Airplanes.
(a) Sideline at 0. 25 Nautical Mile (463 Meters)
(b) Takeoff at 3. 5 Nautical Miles (6482 Meters)
(c) Approach at 1. 0 Nautical Mile (1852 Meters)
Vlll
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LIST OF FIGURES (Cont'd)
Figure Page
17. Range of Compliance Noise Levels for Sideline, 9-45
Takeoff, and Approach Recommended by CARD Study:
(a) Compared with 69 FAR 36
(b) Compared with Mean Levels of 17 Airplane Sample.
(c) Compared with 80 FAR 36
(d) Compared with 85 FAR 36
18. Predicted Noise Levels for Major Acoustical 9-49
Change Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
19. Predicted Noise Levels for New Type Design 9-52
Airplanes.
(a) Sideline
(b) Takeoff
(c) Approach
20. Climb Correction for Horizontal Flight Procedure. 9-55
21. Number of People Impacted by Aircraft Noise : 9-56
1972 Baseline.
22. One-Way Runway Airports for Indicators of Noise 9-57
Impact.
23. Cumulative Noise Exposure at One-Way Runway for 9-58
Large Air Carrier Airport : 840 Operations with
Variable Percent Mix.
(a) Aircraft Mix A (33. 3 % 4-Engine Aircraft)
(b) Aircraft Mix B (16. 7 % 4-Engine Aircraft)
(c) Aircraft Mix C ( 7.14% 4-Engine Aircraft)
(d) Aircraft Mix D ( 4. 76% 4-Engine Aircraft)
(e) Aircraft Mix E ( 0 % 4-Engine Aircraft)
24. Cumulative Noise Exposure at One-Way Runway for 9-63
Large Air-Carrier Airport: Variable Operations
with Constant Percent Mix.
(a) 882 Operations
(b) 280 Operations
(c) 88 Operations
(d) 28 Operations
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LIST OF FIGURES (Cont'd)
Figure Page
25. Cumulative Noise Exposure at One-Way Runway 9-67
for General Aviation Airport: Variable Operations
with Constant Percent Mix.
(a) 800 Operations
(b) 254 Operations
(c) 80 Operations
(d) 26 Operations
(e) 8 Operations
Table LIST OF TABLES
1. Comparison Between Technical Standards of 10-1
FAR 36 and ICAO CAN/4-WP/20.
2. Formulas for Compliance Noise Level Curves. 10-2
3. Summary Noise Levels for Turbojet Propelled 10-3
Airplanes.
(a) 2 - Engines
(b) 2 - Engines (continued)
(c) 2 - Engines (concluded)
(d) 3 - Engines
(e) 3 - Engines (continued)
(f) 3 - Engines (concluded)
(g) 4 - Engines
(h) 4 - Engines (concluded)
4. Noise Levels for Current Technology Existing 10-11
Airplanes.
5. Predicted Noise Levels for Major Acoustical 10-12
Change Airplanes.
6. Predicted Noise Levels for New Type Design 10-13
Airplanes.
(a) I.D. Nos. 1 thru 19.
(b) I.D. Nos. 20 thru 32.
7. Criteria for Noise Impact Analysis of Sensitive 10-15
Land Areas.
8. Contour Levels Enclosed by Noise Indicator 10-16
Rectangles.
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1. INTRODUCTION AND PERSPECTIVES
In 1968, Public Law 90-411 amended Section 611 of the Federal Avia-
tion Act of 1958 to require that, in order to afford present and future
relief and protection to the public from unnecessary aircraft noise and
sonic boom, the Federal Aviation Administration (FAA) shall prescribe
and amend such regulations as the FAA may find necessary to provide
for the control and abatement of aircraft noise and sonic boom. In
addition, PL 90-411 provided detailed specifications that must be con-
sidered by the FAA in prescribing and amending aircraft noise and
sonic boom regulations.
The Noise Control Act of 1972 (Public Law 92-574) supersedes
Public Law 90-411 and further amends Section 611 of the Federal Avia-
tion Act of 1958 to include the concept of "health and welfare" and to
define the responsibilities of and interrelationships between the FAA
and the Environmental Protection Agency (EPA) in the control and
abatement of aircraft noise and sonic boom. Specifically, the Noise
Control Act requires that, in order to afford present and future relief
and protection to the public health and welfare from aircraft noise and
sonic boom, the FAA, after consultation with EPA, shall prescribe
and amend such regulations as the FAA may find necessary to provide
for the control and abatement of aircraft noise and sonic boom.
The Noise Control Act also requires that EPA shall submit to the
FAA proposed regulations to provide such control and abatement of
aircraft noise and sonic boom (including control and abatement
through the exercise of any of the FAA's regulatory authority over
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air commerce or transportation or over aircraft or airport operations)
as EPA determines is necessary to protect the public health and
welfare. The regulations proposed by EPA are to be based upon, but
not submitted before completion of, a comprehensive study to be under-
taken by the EPA and reported to Congress.
The Aircraft/Airport Noise Study, which was completed in August
1973, was required to investigate the:
(1) adequacy of Federal Aviation Administration flight
and operational noise controls;
(2) adequacy of noise emission standards on new and
existing aircraft, together with recommendations
on the retrofitting and phaseout of existing aircraft;
(3) implications of identifying and achieving levels of
cumulative noise exposure around airports; and
(4) additional measures available to airport operators
and local governments to control aircraft noise.
The study was implemented by a task force composed of six task
groups whose product consisted of a report to Congress and six
volumes of supporting data (one volume for each task group). The
reports are identified as References 1 through 7.
Concurrent with the Aircraft/Airport Noise Study, the EPA pre-
pared a general document of criteria in conformance with Section 5(a)(l)
of the Noise Control Act (Reference 8). This "Criteria Document"
reflects the scientific knowledge useful in indicating the kind and extent
of identifiable effects on the public health and welfare which
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may be expected from differing quantities of noise.
In addition, as required by Section 5(a)(2) of the Noise Control Act,
the EPA has prepared a document on the levels of environmental noise,
the attainment and maintenance of which in defined areas under various
conditions are requisite to protect the public health and welfare with
an adequate margin of safety (Reference 9).
The key findings of the "Levels Document" may be summarized as
follows:
(1) The preferred measure for cumulative noise exposure isLeq, the
energy average A-weighted sound level integrated over a 24-hour
period, or Day-Night Level, Ldn. Ldn is essentially the same as
Leq, except that the sounds occurring during night hours (2200
to 0700) are weighted by an adjustment factor of 10 dB to account
for increased annoyance of noise during night hours,
(2) An Ldn of 55 dB has been identified as the noise exposure level
which should not be exceeded in order to protect persons against
annoyance, with an adequate margin of safety.
(3) An Leq of 70 dB has been identified as that noise exposure level
which should not be exceeded in order to protect persons against
permanent hearing impairment, with an adequate margin of safety.
Both of the foregoing levels are daily averages over long periods of
time, rather than maximum allowables for single exposures.
As a result of the Aircraft/Airport Noise Study, EPA determined
that an effective program to protect the public health and welfare with
respect to aircraft noise would require the development and proposal
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to the FAA of regulations in three complementary areas:
(1) Flight procedures regulations standardizing various modes of
noise abatement operations,
(2) Type and airworthiness certification regulations controlling
noise source emissions in the design of new aircraft and by mod-
ification or phaseout of pertain portions of the existing fleet,
(3) An airport noise regulation, which would limit the cumulative
exposure received by noise-sensitive land areas in communities
surrounding airports. Such a regulation, by acting as a perfor-
mance standard for the airport as a complex source, would
require achievement of mutually compatible airport operational
and land use patterns.
The first two types of regulations have been classified within the
following eight aircraft noise regulatory projects to be proposed by the
EPA for promulgation by the FAA under Section 611 of the Federal
Aviation Act as amended.
Flight Procedures
(1) Takeoff
Individual airports, or runways of the airports, can be placed
into the following three main categories regarding community noise
exposure: sideline noise sensitive; near downrange noise sensitive;
and far downrange noise sensitive. A set of three standard takeoff
procedures suitable for safe operation of each type of civil turbojet air-
planes shall be considered for use, as appropriate, to minimize the noise
exposure of the noise sensitive communities.
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(2) Approach and Landing
Standardized approach procedures, suitable for safe operation of
each type of civil turbojet airplanes, shall be considered for use as ap-
propriate to minimize community noise exposure. Examples include re-
ducedflap setting and two segment approach (approximately 6/3 degrees).
(3) Minimum Altitudes
Minimum safe altitudes, higher than are presently specified in the
Federal Aviation Regulations, shall be considered for the purpose of
noise abatement, applicable to civil turbojet powered airplanes regard-
less of category.
Type and Airworthiness Certification
(4) Retrofit/Fleet Noise Level
Approximately 2500 existing turbojet propelled airplanes, having
about 5, 000, 000 operations per year in the United States are not covered
by any noise rule but are the major source of noise impact in the vicin-
ity of at least 500 airports. Regulations shall be considered for the
purpose of minimizing the noise of the existing civil aircraft fleet to
levels as low as feasible by current technology.
(5) Supersonic Civil Aircraft
Regulations shall be considered which would limit the noise gener-
ated by future types of civil supersonic aircraft to levels commensurate
with those required for contempory civil subsonic transports.
(6) Modifications to Federal Aviation Regulations (FAR 36)
Modifications to FAR 36 shall be considered for lowering the com-
pliance noise levels for all new airplane types commensurate with tech-
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nology capability. In addition, various amendments shall be considered
which would improve accuracy, close loopholes, simplify techniques,
and in general, make the rule clearer and more effective.
(7) Propeller Driven Small Airplanes
Noise regulations and standards shall be considered for propeller
driven small airplanes applicable to new type designs, newly produced
airplanes of older type designs, and to the prohibition of "acoustical
changes" in the type design of those airplanes.
(8) Short Haul Aircraft
Noise regulations and standards shall be considered for all aircraft
capable of vertical, short, or reduced takeoff or landing operations.
The required lengths of runways for these operations are being consid-
ered as: 1, 000 ft for VTOL; 2, 000 ft for STOL; and 4, 000 ft for RTOL.
The regulations developed for the above eight projects will repre-
sent a package which, in toto, is expected to bring about a substantial
reduction in the noise environment due to aircraft. While no one regula-
tion by itself, nor the total package, will solve all of the community noise
problems due to aircraft, each one, as a building block, will result in
appreciable improvement. In other words, it is anticipated that the
regulations individually or collectively will effectuate a marked reduction
in the number of persons exposed to undesirably high levels of aircraft
noise. This effect will be additive to the improvement expected over
the next decade or so as the older, noisier aircraft in the U. S. aviation
fleet are retired and replaced with newer, quieter types with greater
functional capabilities.
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In prescribing and amending standards and regulations, Section 611
of the Federal Aviation Act as amended requires that the FAA shall
consider whether any proposed standard or regulation is:
(1) consistent with the highest degree of safety in air
commerce or air transportation in the public interest;
(2) economically reasonable;
(3) technologically practicable; and
(4) appropriate for the particular type of aircraft, aircraft
engine, appliance, or certificate to which it will apply.
The above considerations of safety, economics, and technology are
constraints on the noise regulatory actions which must be made com-
patible with the requirement of protection to the public health and wel-
fare. To achieve compatibility, the regulations must be carefully con-
structed, comprehensive, and definitive instruments for exploiting the
most effective and feasible technology, flight procedures, and operating
controls available.
The regulations proposed by the EPA for promulgation by the FAA
must be practically as complete and comprehensive as the FAA would
propose on their own initiative. Otherwise, conflicts between the
regulatory constraints of safety, economics, and technology and the
requirement of protection to the public health and welfare could delay
constructive action needlessly.
The development of an aircraft noise regulation starts with the
preparation of a project report, which is primarily a background docu-
ment providing as much information as possible on such matters as
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health and welfare; current, available, and future technology, cost-ef-
fectiveness, and recommended criteria for levels, measurements, and
analyses. The project report provides the basic input necessary for the
preparation of a notice of proposed rulemaking (NPRM), which is the
format of each regulation to be proposed by the EPA to the FAA.
The EPA published a "Notice of Public Comment Period" in the
Federal Register on 19 February 1974 concerning aircraft and airport
noise regulations (Reference 10). This Notice identified the eight areas
discussed above as candidates for regulatory actions which could be
effective in controlling aircraft noise. The purpose of the Notice was to
invite interested persons to participate in EPA's development of the
regulations to be proposed, by submitting such written data, views, or
arguments as they may desire. The Notice was not definitive in regard
to any particular proposed regulation but referred to them in a general
way. Information was solicited relating to the basic requirement that
the regulations contribute to the promotion of an environment for all
Americans free from noise that jeopardized their health or welfare, and
to the four statutory constraints pertaining to safety, economics, and
technology. The aviation community, therefore, was put on notice in
early 1974 that regulatory activities were underway by the EPA and
were informed of the general nature of the proposed regulations. Subse-
quent developments have not changed the direction to any appreciable
extent.
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2. SYSTEMS CONTROL OF AIRCRAFT NOISE
Protection to the public health and welfare from aircraft noise is
accomplished most effectively by exercising four noise control options
taken together as a system:
(1) Source control consisting of the application of basic
design principles or special hardware to the engine/
airframe combination which will minimize the gen-
eration and radiation of noise;
(2) Path control consisting of the application of flight
procedures which will minimize the generation and
propagation of noise;
(3) Receiver control consisting of the application of
procedures susceptible to control by airport com-
munities such as restrictions on the type and use of
aircraft at the airport which will minimize community
noise exposure; and
(4) Land use control consisting of the development or
modification of airport surroundings for maximum
noise compatible usage.
In general, the primary approach for noise abatement is to attempt
to control the noise at the source to the extent that the aircraft would
be acceptable for operations at all airports and enroute. And in prin-
ciple, aircraft noise can be controlled extensively at the source by
massive implementation of technology. In practice, however, the techno-
logical capability for complete control without exorbitant penalties is not
yet available and may never be. A regulation requiring full protection to
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the public health and welfare by source control, therefore, would have
the effect of preventing the development of most new aircraft and
grounding the existing civil fleet.
Path control, for most cases, can be an effective option for
substantial reduction of aircraft noise. Furthermore, it has the
advantage that the results are additive to those obtained by source
control. However, specialized flight procedures are limited because
of the need to maintain the highest degree of safety. Therefore, a
regulation requiring full protection to the public health and welfare
by flight procedures is not feasible at this time and probably never will
be. Nevertheless, all aircraft can be flown safely in various modes
that produce a wide range of noise exposure. And, at the least, those
safe modes, which will minimize the generation and propagation of
noise, should be identified and standardized.
The major problem with aircraft noise in terms of numbers of
people exposed, occurs in the vicinity of airports. This problem could
be relieved by the application of various operating restrictions at the
airport. Extensive use of airport restrictions, however, is cost-ef-
fective only if all feasible source and path control options have been
implemented. Unless this has been done, the airport restrictions may
result in unnecessary damage to the local and national economy,
A concept under consideration at this time is that the airport
authorities in some cases, and the FAA in other cases, would impose
restrictions on the aircraft operators as needed (curfews, quotas,
weight and type limitations, preferential runway use, noise abatement
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takeoff and approach procedures, landing fees, etc.) to ensure that
the airport neighborhood communities are noise-compatible consistent
with the requirements of health and welfare. The restrictions available
to the airport operator would be those approved by the FAA, CAB, and
EPA. The highest degree of safety must be maintained and interstate
and foreign commerce requirements must be considered. Restrictions
involving flight safety and air traffic control would be the sole respon-
sibility of the FAA.
As an example of this concept, determination of runway usage to
minimize community noise impact would be made by the airport
operator after consultations with the municipal authorities of the
airport neighborhood communities. High priority should be given to
maximum implementation of long range land use planning for noise
compatibility. If the FAA agrees with the operator's runway desig-
nations, the FAA would decide which takeoff and approach procedures
would be implemented by aircraft using the designated runways. In
all cases, pilots and air traffic controllers would be given discretionary
authority over operating procedures for safety and air traffic reasons.
After all feasible noise control measures have been applied to the
aircraft by design, treatment, or modification of the source, by flight
and air traffic control procedures, and by proper design, location and
use of airports, aircraft noise may still be a problem at some locations.
In this event, noise compatible land use is probably the only remaining
solution. The land use control option is more easily exercised in the
development of new airports than as a remedial measure for existing
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noise impacted communities. For the latter case, the costs of land
use control may be so high that maximum effort should be devoted to
implementing the source, path, and receiver control options taken
together as a system.
The extent to which the control options should be regulated is depen-
dent upon the meaning and quantification of public health and welfare.
Three important considerations must be emphasized. First, the EPA-
proposed and the FAA-prescribed noise regulations have the requirement
of protection to the public health and welfare. Second, the regulations
are constrained by safety, economics, and technology. Third, although
the requirement and the constraints may appear to be in opposition to
each other, resolution can be accomplished by implementation of the
noise control options taken together as a system.
The foregoing discussion is relevant to the basic fact that aviation
is a needed element of the national transportation system. If regulations
intended to protect the public health and welfare imposed such a burden
that the survival of the national aviation system were threatened, this
result would not be in the national interest. On the other hand, well-
conceived regulations which optimally exploit the available alternatives
would protect the public health and welfare and, by improving the ac-
ceptability of aircraft, encourage continuing development of the aviation
system.
If it could be established that any of the three options involving de-
sign techniques or hardware applications, flight procedures, or airport
restrictions could feasibly satisfy the requirements for protection
to the public health and welfare from airport noise, then that option
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probably should be used. It is unlikely, however, that any single op-
tion, within the legislative constraints of safety, economics and tech-
nology, could completely satisfy the requirements for such protection.
Consequently, a systems implementation of the four noise control op-
tions should be considered as the most feasible method for accomplishing
the desired objectives and equitably sharing the costs of noise control
among all segments of the aviation community and that portion of the
public that benefits from aviation.
Noise regulations that pertain to source emissions or flight proce-
dures of specific types of aircraft not yet produced cannot be expected
to predict such unknowns as the quantity of these aircraft that eventually
will be produced, from what airports (or runways) they will be operated,
or what noise-compatible land use can or may be implemented in the
vicinity of these airports. Consequently, source emissions or flight
procedures regulations should be developed with the understanding that
protection to the public health and welfare will be accomplished by im-
plementation of the total system concept.
The regulations should be of the "umbrella" type in the sense that
those aircraft regulated can all comply by use of current technology al-
though some may be capable of and are achieving lower noise levels
than others. The various aircraft/engine types have different weights,
thrust, engine characteristics, and flight performance characteristics,
all of which influence their noise generation and reduction capabilities.
Consequently, it is not reasonable to expect that a particular source or
flight procedures regulation should require equal noise level compliance
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from all types of aircraft. However, all aircraft should be required to
implement current noise control technology to the maximum extent feas-
ible for their type. Also, various models of aircraft within a specific
type classification may not have the same capability for generating
or controlling noise because of differences in size, weight, power-
plant, etc. The regulations should be flexible enough to consider the
effect of these growth factors on noise and attempt to control the levels
to the maximum practical extent.
"Umbrella" type regulations do not mean that the worst offenders
would be permitted to comply without penalty. On the contrary, a prop-
erly constructed set of regulations, representing components of a system
of noise control options, probably would require ultimately the greatest
sacrifice from the worst offender. As an example, FAR 36 has several
features that discriminate, in the "umbrella" sense, among the various
classes of airplanes. Greater weight airplanes are permitted higher
compliance levels; four engine airplanes are permitted greater sideline
distances; but four engine airplanes are not permitted as much percent
thrust reduction at takeoff. The above discriminating features contained
in the same source control regulation permit some airplanes to make
more noise than others. In the end, however, the airplanes producing
the most noise will be the primary candidates for operating restrictions
at the airports as necessary to protect the public health and welfare.
Implementation of these restrictions is likely to impose the greatest
burden on the noisiest airplanes.
The airport restrictions would provide incentive for the aircraft man-
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ufacturers and operators to conduct thorough investigations and con-
sider maximum utilization of current noise control technology. The
fact that an aircraft manufacturer or operator has barely complied
with an "umbrella" type certification or flight procedure regulation
should not ensure unlimited acceptance of a particular airplane at all
airports. The possibility that airport restrictions might inhibit use,
would, therefore, encourage the aircraft operators and manufacturers
to satisfy the FAA regulations by maximum utilization of the source
emissions and flight procedures noise control technology within their
capability and not merely to comply with specified limits.
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3. BACKGROUND OF EXISTING AIRCRAFT NOISE REGULATIONS
Five regulations, or amendments thereto, have been prescribed
which have a significant influence on aircraft noise and sonic boom.
These rules, identified as References 11 thru 15, accomplish the fol-
lowing:
(1) Reference 11 ( FAR 36 ) prescribes noise standards for the
issue of type certificates, and changes to those certificates,
for subsonic transport category airplanes, and for subsonic
turbojet powered airplanes regardless of category. This rule
initiated the noise abatement regulatory program of the FAA
under the statutory authority of Public Law 90-411.
(2) Reference 12 is an operating rule prohibiting supersonic
flights of civil aircraft except under terms of a special
authorization to exceed the speed of sound (Mach 1. 0). Au-
thorization to operate at a true Mach number greater than
unity over a designated test area may be obtained for special
test purposes. Authorization for a flight outside of a desig-
nated test area at supersonic speeds may be made if the ap-
plicant can show conservatively that the flight will not cause
a measurable sonic boom overpressure to reach the surface.
(3) Reference 13 requires new production turbojet and transport
category subsonic airplanes to comply with FAR 36, irrespec-
tive of type certification date. This rule established the
following dates by which new production airplanes of older type
designs must comply with FAR 36.
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1 December 1973 for airplanes with maximum weights
greater than 75, 000 pounds, except for airplanes that
are powered by Pratt and Whitney JT3D series engines.
31 December 1974 for airplanes with maximum weights
greater than 75, 000 pounds which are powered by Pratt
and Whitney JT3D series engines.
31 December 1974 for airplanes with maximum weights
of 75, 000 pounds and less.
(4) Reference 14 is an amendment to FAR 36 whose purpose is to
tighten the conditions under which an applicant for an acousti-
cal change approval must show that modifications of certain
turbojet or transport category airplanes will not increase the
takeoff or sideline noise levels of those airplanes. Three
changes are made to the acoustical change provision of FAR 36
which will significantly decrease community noise impact by
preventing methods of circumventing that provision. The three
changes which effectively close loopholes are:
Thrust reduction is not permitted.
Test airspeed is more precisely specified.
The quietest approved configuration for the highest
approved takeoff weight must be used.
(5) Reference 15 prescribes noise standards for:
The issue of normal, utility, acrobatic, transport, and
restricted category type certificates for propeller driven
small airplanes (12,500 pounds maximum weight).
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The issue of standard airworthiness certificates and
restricted category airworthiness certificates for newly
produced propeller driven small airplanes of older type
designs.
The prohibition of "acoustical changes" in the type de-
sign of those airplanes that increase their noise levels
beyond specified limits.
It should be noted that the EPA has objected to the regulation of Refer-
ence 15 as being too lenient and has proposed one significantly more
stringent which was published in the Federal Register on the same date
as Reference 15 (40 FR 1061).
FAR 36 was the first type certification regulation for aircraft noise
prescribed by any nation. It is a comprehensive, highly technical rule
appropriate to the sophisticated sound source (aircraft) it is designed
to regulate. The development of the basic concepts inherent in FAR 36
was, for the most part, the result of the experience of government and
industry not only of the United States but of France and the United
Kingdom as well. Government representatives of these nations formed a
"Tripartite" working group which provided most of the initial ideas and
coordinated the technology upon which FAR 36 is based. Subsequently,
representatives of Germany, Japan, the Netherlands, and Sweden par-
ticipated in the working group and made valuable contributions. The
seven nations involved represented the major aircraft manufacturing
nations of the world (except for the U. S. S. R. ) and were able to pool
their specialized knowledge and experience to provide a substantial
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technology base for the development of aircraft noise regulations.
It must be emphasized that various national and international
organizations* provided valuable background data in such areas
as noise measurement procedures, electronic equipment characteris-
tics, atmospheric attenuation of sound, and noise evaluation measures.
Where these organizations had issued approved citable documents
that were relevant, they were included as references in FAR 36
In many cases, however, the areas were so new that the only doc-
uments available were draft working papers. Where appropriate, such
material was included (but not referenced) in FAR 36.
The United States was the first nation to take advantage of this
wealth of information and include it in a noise control regulation pub-
lished in November 1969 as FAR 36. Shortly thereafter, in December
1969, the International Civil Aviation Organization (ICAO) recommended
standards (Reference 16) which, subsequently, were adopted by the
Council of ICAO in April 1971 as Annex 16 to the Convention of Interna-
tional Civil Aviation (Reference 17). FAR 36 and Annex 16 are essen-
tially the same rules; FAR 36, however, being slightly more stringent.
Most nations have adopted Annex 16 as their type certification rule
for aircraft noise and because the rules are so similar, no major prob-
lems have arisen in regard to reciprocity between the United States
rule FAR 36 and Annex 16 for the rest of the world.
* American NationalStandards Institute (ANSI), International Electro-
technical commission (IEC), International Standards Organization (ISO),
Society of Automotive Engineers (SAE).
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4. OBJECTIVE
The objective of this project is to propose a rule which will
control the noise of certain turbojet and propeller driven airplanes to
levels as low as is consistent with safe technological capability, and
which:
(1) will be fully responsive to the recommendations of Reference 9
for protection to the public health and welfare,
(2) will not impose unreasonable economic burdens on the national
aviation system,
(3) will not degrade the environment in any manner, and
(4) will not cause a significant increase in fuel consumption.
The intent of this project report is to provide as much definitive
information as possible on such matters as health and welfare, tech-
nology, cost effectiveness, and recommended criteria for levels,
measurements, and analyses. This project report will provide the
basic input for the preparation of a notice of proposed rule making
(NPRM) which will be the format of the regulation to be proposed by
the EPA for promulgation by the FAA in conformance with the Noise
Control Act of 1972.
The noise rule should have the earliest practical effective date,
should be a requirement for the operation of certain turbojet and pro-
peller driven airplanes in the United States and thereby:
(1) insure that future community noise exposure due to the opera-
tion of these aircraft has been reduced to the lowest feasible
levels and smallest practical areas commensurate with the cur-
rent state of the art,
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(2) provide a regulatory maximum noise level limit on these -air-
planes to form a basis for meaningful long-range land use plan-
ning in the vicinity of airports,
(3) provide economic incentives for the development of quieter
airplanes by limiting the development of noisy ones,
(4) permit the fullest practical range of airplane design options so
that cost-effective noise reduction can be achieved.
Specifically, what is under consideration here is an amendment to
the existing Federal Aviation Regulation Part 36 (FAR 36), Reference
11. FAR 36 is a type certification regulation which applies to certain
kinds of airplanes designated as types. Only one airplane of each type
need be tested and the results of the tests are assumed valid for all
individual airplanes produced of that type. A type certificate signifies
that an aircraft type design has been demonstrated to conform to FAA
standards on airworthiness and noise. Each aircraft requires an air-
worthiness certificate that signifies that the specific aircraft has been
manufactured in accordance with its FAA certified type design and has
subsequently been maintained according to regulations.
FAR 36 has several purposes. Its main purpose is to provide re-
quirements which will influence the design of aircraft to include imple-
mentation of noise source control technology to the maximum extent
feasible. As defined in Section 2, source control consists of the ap-
plication of basic design principles or special hardware to the engine/
air frame combination which will minimize the generation and radiation
of noise. And as used here, feasibility means that the noise control
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technology shall be compatible with the regulatory constraints of safe-
ty, economics, and technology discussed in Section 1. In other words,
the technology shall: (1) be consistent with the highest degree of safety;
(2) be economically reasonable; (3) be technologically practicable; and
(4) be appropriate for the particular type of aircraft.
Another purpose of FAR 36 is to provide meaningful noise levels
for specific types of aircraft which will be useful in predicting the noise
impact in airport neighborhood communities. It must be understood
that since FAR 36 is a type certification regulation, the data resulting
from the certification process will be limited in its extent insofar as
community noise impact studies are concerned. Nevertheless, FAR 36
should require the acquisition and reporting of data which can be util-
ized in such studies.
Another purpose of FAR 36 which is fundamental to the other pur-
poses is the setting of standards for the acquisition and reduction of
aircraft noise and flight performance data. Without standards, noise
measurements of aircraft have no real credibility. Without good stand-
ards, noise requirements may not be effective. Imprecise meanings,
careless terminology, or inadequate testing procedures can lead to
circumvention of the intent of the rule. In other words, loopholes should
not exist which can be exploited by those manufacturers who have air-
planes that have problems meeting the noise requirements.
The objectives of the amendment to FAR 36, as developed and pro-
posed in this project report, are to strengthen and extend the original
purposes of FAR 36. Since the promulgation of FAR 36 in 1969, noise
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control technology has advanced substantially. The noise compliance
requirements should reflect this technology growth and be structured
with respect to time to encourage the application of future technology
whenever it is determined to be feasible.
The methods for determining community noise impact are better
understood now than in 1969. Consequently, amendments to FAR 36
should include requirements for the acquisition and/or reporting, to a
reasonable extent, of data useful for predicting the impact of aircraft
noise.
The procedures for type certification of aircraft noise also are
better understood now than five years ago. The considerable experience
gained in the United States and abroad should be utilized to simplify
techniques, improve accuracy, and eliminate ambiguities. Advancements
in the electronic data acquisition and reduction systems should be re-
flected in the standards in order to improve efficiency and reduce costs.
The major aircraft manufacturing nations, including the United
States, have been active in coordinating their experience and working
toward amending Annex 16 to reflect their aggregate experience and up-
date the standards for the acquisition and reduction of aircraft noise
and flight performance data. The results of this work were discussed
as Agenda Item 3 during the fourth meeting of the ICAO Committee on
Aircraft Noise (CAN/4) held in Montreal 27 January - 14 February 1975.
In preparation for CAN/4, the working papers and other documents
listed as References 18 thru 42 were circulated. Most of the working
papers reflect national or organizational interests and should be
4-4
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considered accordingly. However, the report of ICAO Working Group D
(Reference 19) represents the work of many nations, including the
United States. It presents a very comprehensive set of recommenda-
tions for amending Annex 16 to make the noise specifications more
severe.
It is desirable but not necessary that amendments to FAR 36 and
Annex 16 be similar. The United States has its own requirements
(Noise Control Act of 1972) which, in many respects, are more strin-
gent than those of most other nations. Consequently, the recommen-
dations of Working Group D and those of the other working papers were
examined for their relevancy and used accordingly. Nevertheless, the
international aviation community has done outstanding work in the area
of aircraft noise and its control and their results are referred to ex-
tensively in the following Analyses section.
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5. ANALYSES
A. Technology Options and Applications for Source Noise Control
Source noise control, as defined previously, is the application of
basic design principles or special hardware to the engine /airframe
combination which will minimize the generation and radiation of noise.
The technology of source noise control is time-dependent in the sense
that it is based upon the results of past, present and future programs
of research, development, and demonstration (RD & D) which can be
classified as follows:
(1) Current technology includes "shelf item" hardware and com-
monly known (state of the art) techniques and procedures which
have been used effectively by most manufacturers for many
applications.
(2) Available Technology includes "shelf item" hardware and com-
monly known (state of the art) techniques and procedures which
have been used effectively by some manufacturers for some
applications. Also included are the results of RD&D which have
not been put into practice but are available for implementation.
Some performance testing may stillbe necessary but this tech-
nology has been certificated for airworthiness or- by adequate
ground and/or flight testing, determined to be capable of being
certificated.
(3) Future technology represents the outcome of RD & D programs
now in progress which have not been verified but the results to
date indicate high potential to a reasonable degree of confidence.
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Included are present RD&D programs which are being con-
ducted with sufficient resources of manpower, funding, and
time to carry the programs to conclusion. Definitive results
are expected in the relatively near future for acoustical and
operational performance, economics, and flight safety. The
nature of the expectations is positive because predictions of
non-viable results would have been cause for earlier term-
ination of the RD&D programs.
The application of source noise control technology is directed to
either existing or new aircraft. In the case of existing aircraft, source
control is applied by retrofitting modified engines or acoustical treat-
ment to the engines / nacelles during a non-operative or shutdown
period. * In the case of new production aircraft, source control is ap-
plied during the manufacturing process.
The source control measures available for existing and for newly
produced aircraft of the same type design will be 'essentially the same.
Acoustical treatment that is effective for one will be effective for the
other as well. Also, there is opportunity for making some, but limited,
changes in the basic engine/airframe design of the older type aircraft.
The extent of these changes will be governed by the amount of their
influence on the function of other parts of the aircraft and on overall
safety, performance, and cost. For example, modifying an aircraft
* As used here, acoustical treatment means any hardware or mech-
anical device, applied either singly or combined to the inlet and
primary and secondary exhausts, that either will absorb sound or
otherwise effect a noise reduction at one or more of the FAR 36 meas-
urement points.
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to obtain a higher thrust to weight ratio would require larger size
engines which might require revisions to the landing gear, pylons,
wing and tail structure, the addition of ballast, etc. Obviously, if at
all justifiable, such modifications are more cost effective for newly
produced aircraft than for existing aircraft.
The most effective use of technology to achieve maximum noise
control is in the design and development of new aircraft types.
Applications of basic design principles and acoustical treatment for
the control of noise can be exploited optimally when they can be inte-
grated from the beginning into the overall air craft/engine design. Mo-
difications such as retrofit hardware are always the least efficient,
but sometimes necessary, use of technology.
Regulations for the control of aircraft noise, such as FAR 36,
should be constructed to fully represent the use of the three time-
dependent technology options and to be applicable to the four classes
of aircraft listed as follows:
(a) Noise Control Technology Options
(1) Current
(2) Available
(3) Future
(b) Aircraft Classes
(1) Existing Aircraft
(2) New Production Aircraft-Older Type Design
(3) New Production Aircraft Acoustical Changes to Older
Type Designs
(4) New Production Aircraft-New Type Design
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The compliance noise levels of FAR 36 as effective to date, which
includes the original version (Reference 11) and three amendments
(References 13 thru 15), are applicable to all four classes of aircraft
but are not representative of the current, available, and future tech-
nology options. Only pre-1969 acoustical technology is represented.
Additional amendments to FAR 36 should correct this deficiency by
specifying compliance noise levels to be met at specified dates repre-
sentative of available, and future technology, as well as current. The
dates for future technology must, of course, be an estimate because
no matter how favorable technology of the future appears, the final
results of the RD&D programs could be negative. Consequently, the
compliance dates for future technology should be flexible and be
capable of being extended if necessary.
Furthermore, in order to insure that the flexibility of compliance
dates are maintained, it is recommended that FAR 3 6 be reviewed every
five years oroftener. Appropriate sections of FAR 36 should be updated
where feasible to reflect the technology options and measurement
standards, practices, and procedures that are practicable and appro-
priate for the aircraft types at that time. Consideration should be
given at each quinquennial review to the inclusion of the previous ex-
perience in noise certification and on such matters as whether the
noise control technology is sufficiently advanced to be considered for
retrofitting operational aircraft and requiring newly produced aircraft
of older type designs to comply with more stringent noise levels.
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B. Technical Standards of FAR 36
Aircraft are very complex equipment producing a great deal of me-
chanical power necessary for propulsion; a portion of this power is
wasted as noise. Aircraft noise signatures, reflecting the complexity
of the source, are among the most intricate of the common noise
sources. They involve complicated interrelated spectral, temporal,
and spatial functions of sound pressure, all of which are important
because of the high sensitivity of the human ear. The control of aircraft
noise is complicated by the fact that the human ear, because of its
sensitivity, is able to be adversely affected by relatively small quanti-
ties of acoustical power. The acoustical power of an aircraft is only
a very small fraction of the total mechanical power which it produces.
Hence, noise suppression techniques are handicapped by the need to
provide a radical change to a small fraction of the total mechanical
power without significantly affecting the power needed for propulsion.
As discussed in Section 3, the main purpose of FAR 36 is to provide
requirements which will influence the design of aircraft to include im-
plementation of noise source control technology to the maximum extent
feasible. The setting of standards to accomplish this purpose is dif-
ficult because the control of the noise itself is difficult, for the reasons
discussed above. If, for example, the requirements for testing, meas-
uring, and evaluating the noise are not defined accurately, the noise
control techniques used by the manufacturer are apt to be misdirected,
resulting in wasted performance and cost. Consequently, the stand-
ards of FAR 36 should be examined and updated periodically to insure
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that the latest experience and technological advancements are ex-
ploited so that such problems are minimized.
The technical standards of FAR 36 are contained in Appendixes A,
B, C, and F of FAR 36. Appendix A contains the test and measure-
ment conditions, the correcting and reporting of measured data, the
corrections for the atmospheric attenuation of sound, the corrections
for flight procedures, and the specifications for electronic data ac-
quisition, reduction, and analysis equipment. Appendix B contains the
methodology for computing the noise evaluation measure, Effective
Perceived Noise Level (EPNL) in units of EPNdB, including the effects
of spectral irregularities and noise duration. And Appendix C con-
tains the specifications for the noise measuring points, the compli-
ance noise levels, and the takeoff and approach flight test conditions.
Appendix F pertains exclusively to propeller driven small airplanes
and will not be discussed here.
The following discussions of this section (Analyses) will be organ-
ized according to the individual sections of Appendixes A, B, and C of
FAR 36. Pagination throughout the remainder of the Analyses Section
is keyed to the appropriate Appendix; e.g., pages 5A-1, 5B-1, and
5C-1 initiate the discussions relating to Appendixes A, B, and C of
FAR 36, respectively. Specific items in those sections will be ex-
amined for accuracy (or relevancy) in view of the experience gained,
both in the United States and abroad, in noise certification procedures.
The experience of the international aviation community, including the
United States, is well documented by the ICAO Working Group D report
(Reference 19) and will be evaluated in depth. In fact, the corres-,
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pondence between the material in Appendixes A, B, and C of FAR 36
and that in Appendixes CI and C of the Working Group D report is
very close as can be seen by the comparisons in Table 1. Also,
the experience of other organizations, both United States and foreign,
will be evaluated individually in relation to specific topics.
The intent of the Analyses Section is: (1) to delineate the problem
areas inherent in Appendixes A, B, and C of FAR 36; (2) to identify
problems that can and should be corrected at this time and recommend
iKiethods of solution; and (3) to provide material appropriate for amend-
ing the appendixes. Whenever it is reasonable to do so, the amendments
will be structured to be compatible with the recommendations of
CAN/4. However, other sources of information will be considered as
well. National and International standards as appropriate will be cited
as references in accordance with United States regulatory procedures
[1 CFR Part 51]. For example, References 43 thru 113 are various
standards, recommended practices, and information reports pertinent
to aircraft noise measurement, evaluation, and control which were
evaluated and considered for citation. Although some of the cited
documents have draft and not final status, they were included on the
basis that their information represents the latest available ideas of
some portions of the scientific community. It is important to the public
health and welfare that FAR 36 be amended soon and that as many con-
cepts for modifications as possible be evaluated. It is not prudent,
therefore, to wait until standards setting organizations have issued
final documents, which may take many years, before taking action
on FAR 36. The purpose, ideally, is to work toward truly international
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standards so that all aircraft throughout the world are evaluated and
regulated for noise identically. However, as mentioned previously,
the United States has its own requirements which in some cases may
be more stringent than those of other Nations.
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C. Noise Certification Test and Measurement Conditions (§A36. 1 of
FAR 36).
(Cl) General
This section of Appendix A of FAR 36 prescribes the general test
conditions under which aircraft noise type certification tests must be
conducted, the testing procedures and the measurements that must
be taken to determine the aircraft noise.
Experience in noise certification testing conducted since 1969 in
the United States and other nations has shown that various aspects
of the test and measurement conditions should be clarified and strength-
ened. The modifications recommended in the following discussion will
have the effect of imposing more restrictive test provisions
which will further limit the periods of time during which some test
facilities may be used for certification test purposes. They will also
increase the amount of meteorological data required to demon-
strate that the required conditions have been met. Imposing these
changes, will however, disallow testing under conditions which produce
results which are not representative, reliable, or reasonably consistent
with what might be expected under standard conditions.
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(C2) General Test Conditions
§A36. l(b)(2) specifies that:
"Locations for measuring noise from, an aircraft in
flight must be surrounded by relatively flat terrain
having no excessive sound absorption characteristics
such as might be caused by thick, matted, or tall
grass, shrubs or wooded areas."
In a draft chapter on noise type certification for the FAA Regional
Offices (Reference 114) the FAA has indicated that: §A36.1(b)(2) does
not clearly define surfaces having no excessive sound absorption char-
acteristics; the intent of the section is to insure diffuse reflection,
not to permit the use of a surface with anechoic properties such as
loosely spaded earth, grass over a few inches in height, or any
vegetation (particularly when wet). The FAA also indicated that:
variations in one-third octave band sound pressure levels can be as
much as 6dB if the surface is completely absorptive as compared with
completely reflective, and that research and development efforts to
provide a more accurate and concise definition of excessive surface
absorption were in process. In this regard, an FAA report (Ref-
erence 115) indicates that some tests were conducted wherein the effects
of variation in the type of microphone ground plane on aircraft noise
were studied; however, the results of those tests are not reported
in Reference 115.
Other organizations have also indicated that there has been some
concern about being more specific about the nature of the terrain (or
.ground plane) in the immediate vicinity of the microphones. For
instance; in June 1974, a draft proposal of the International Standards
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Organization's (ISO) Recommendations R507 and R1761, "Procedure
for Describing Aircraft Noise Heard on the Ground", provided the
following specification:
"The ground surface over an area 6 m x 6 m sur-
rounding the microphone position shall consist of
concrete or asphalt or plywood at least 12 mm thick
or an equivalent highly reflecting material. For
measurements directly under the nominal flight path
the microphone shall be in the center of the square.
For other measurements the microphone shall be
positioned so that at least 5 m of the reflecting
surface is between the aircraft and the microphone.
Within a radius of one metre centred on the micro-
phone position the surface shall be flat within +_ 5 mm;
elsewhere within the square it shall be flaT within
+_ 30 mm. Overall the surface shall be horizontal
within a tolerance of + 3%. "
In September 1974, the U.S. Committee reviewing the draft proposal
noted that the attempt to better the definition of "excessive absorption"
was commendable, objected to the use of plywood, and recommended
the entire restrictive subclause be removed from the document. At a
meeting of the ISO/TC43/SC1/WG2 in October 1974, the restrictions
were downgraded to an advisory note and a suggestion that a hard con-
crete surface was desirable.
Although the ISO draft recommendations were considered by the
ICAO CAN/4 Working Group D, this group did not propose any changes
to the ICAO Annex 16 in this regard; therefore, those provisions of
Annex 16 remain essentially identical to the vague provisions of §A36.1
(b)(2) of FAR Part 36.
The irregularity of the surface and the uncertain impedance of the
terrain in the vicinity of the microphone position has contributed to
the unmanageable variability in the noise measurements of aircraft for
5A-3
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certification purposes. Until measurement conditions such as
this are more rigorously defined and controlled, the overall effect
of unspecified ground plane on the EPNL will remain uncertain and
debates on such matters as ground-to-ground propagation as a function
of elevation angle, shielding and some "pseudo tones" will continue
unresolved except through the use of increased sample size to over-
come the variability of the data.
Specifying more restrictive characteristics for the terrain in the
immediate vicinity of the microphones has the disadvantage of limiting
the number of useful tests sites and, in fact, may eliminate the use
of some sites previously used for this purpose. This is particularly
true for sideline noise measurements where a multiplicity of meas-
urement sites are required in order to locate the point where the
sideline noise is demonstrated to be a maximum.
At the potential expense of measurement site selection, but in the
interest of achieving more consistent, reliable and understandable
results, the ground plane in the immediate vicinity of the microphone
should be more restrictively defined. The language of 1SO/TC43/.
SC1/WG2, quoted above, without reference to a plywood surface,
would be appropriate for this purpose.
§A36. l(b)(2)also specifies that "No obstructions which significantly
influence the sound field from the aircraft may exist within a conical
space above the measurement position, the cone being defined by an
axis normal to the ground and by a half-angle 75 degrees from this
axis. " The recent proposal to modify a similar restriction in ICAO's
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Annex 16 (Reference 19) included a modification to increase the cone's
half-angle to 80 degrees from 75 degrees. The above cited draft of ISO
R507 and R1761 also specifies a clear zone half-angle of 80 degrees.
However, from the FAA draft report on Project No. AEQ-75-
5-R, the FAA is considering moving in the opposite direction; that is,
allowing a less restrictive specification to "temper the requirement
in A36.1(b)(2)" (page 4, Reference 116). The FAA has presented no
information or data to justify its proposal which would allow off-the-
line-of-sight obstructions (potential reflectors) to interfere with
sideline noise measurements.
In the interest of ensuring adequate clear space, especially for the
sideline noise measurements, and being consistent with the more
restrictive international standards (ICAO and ISO) consideration
should be given to modifying §A36.1(b)(2) to specify a half-angle of
80 degrees instead of the currently specified 75 degrees. This mod-
ification is simple; should cause no additional measurement site
location or logistics problems; and have, compared to the unspecified
ground plane, little effect on previous or future measurements.
In consideration of the above, the recommended wording for
§ A3 6.1 (b)(2) is as follows:
(2) Location for measuring noise from an aircraft in flight must
be surrounded by relatively flat terrain. The ground surface
over an area at least 6 meters (19.69 feet) square surrounding
the microphone position shall consist of highly sound reflecting
material such as concrete, asphalt, or other approved
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material at least 12 millimeters (0.47 inches) thick. For
measurements directly under the nominal flight path, the mic-
rophone shall be in the center of the reflective surface. For
other measurements, the microphone shall be positioned so
that at least 5 meters (16.40 feet) of the reflecting surface is
between the aircraft and the microphone. Within a radius of
one meter (3.28 feet) centered on the microphone position,
the surface shall be flat within + 30 millimeters (1.18 inches).
Overall, the surface shall be horizontal within a tolerance
of + 3 percent. No obstructions which significantly influence
the sound field from the aircraft shall exist within a conical
space above the point on the ground vertically below the
microphone, the cone being defined by an axis normal to the
ground and by a half-angle 80 degrees from this axis.
§A36.1(b)(3) prescribes the following weather conditions:
"(i) No rain or other precipitation.
(ii) Relative humidity not higher than 90% or lower than 30%.
(iii) Ambient temperature not above 86 DF and not below 41° F at
10 meters above ground.
(iv) Airport reported wind not above 10 knots and crosswind
component not above 5 knots at 10 meters above the
ground.
(v) No temperature inversion or anomalous wind conditions
that would significantly affect the noise level of the air-
craft when the noise is recorded at the measuring points
defined in Appendix C of this part. "
FAA experience in developing the noise definition of the DC-8-61
aircraft (Reference 32), and more recently, during some tests using
a DC-9 (Reference 115), the FAA has demonstrated the significant
influence atmospheric conditions may have on aircraft noise measure-
5A-6
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merits and the necessity of prescribing a more restrictive range
of atmospheric conditions under which aircraft noise certification tests
may be conducted. In order to attain more accurate and consistent
noise certification data and to establish greater confidence in ICAO's
Annex 16, the U.S. delegation to CAN 4 recently proposed (Reference
32) adoption of a revised temperature and relative humidity test enve-
lope. The proposal would modify the current limits to exclude testing
v outside a temperature/relative humidity window defined by 41 to 95
degrees F (5 to 35 degrees C) and 30 to 95 percent relative humidity
and when the rate of atmospheric attenuation exceeds 10 decibels/100
meters for the one-third octave band centered at 8, 000 Hertz. The
ICAO proposal further specified that these limits be imposed at the
surface and along the contiguous noise path to the test airplane.
The ICAO proposal is slightly more restrictive than the ISO
recommendations R507 and R1761 upon which it is based. The ISO
recommendations simply restricted testing under conditions which
would result in atmospheric absorption in excess of 10 dB/100 meters
in the one-third octave band centered at 8 kHz but did not impose
the additional temperature and relative humidity limits. The
difference between the ICAO proposal and the ISO recommendations
is illustrated in Figure 1.
In consideration of the above, the recommended wording for
§A36.1 (b)(3) is as follows:
5A-7
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(3) The tests must be carried out under the following atmospheric
conditions:
(i) No precipitation.
(ii) Relative humidity not higher than 95 percent nor less
than 30 percent.
(iii) Ambient air temperature not above 95 degrees F (35 de-
grees C) nor below 41 degrees F (5 degrees C).
(iv) Airport reported wind not above 10 knots and crosswind
component not above 5 knots at 10 meters (32.80 feet)
above ground.
(v) No temperature inversion or anamolous wind or humidity
conditions that would significantly affect the noise level
of the aircraft when the noise is recorded at the measuring
points defined in Appendix C of this Part. The relative
humidity and ambient temperature over the entire noise
path between ground and airplane must be such that the
sound attenuation in the third octave band centered on
8 kHz will not be greater than 10 dB per 100 meters
(328.08 feet).
5A-8
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(C3) Aircraft Testing Procedures
§A36.1 (c)(3) states:
"(3) The aircraft position along the flight path must
be related to the noise recorded at the noise
measurement locations by means of synchronizing
signals. The position of the aircraft must be re-
corded relative to the runway from a point at least
4 nautical miles from threshold to touchdown during
the approach and at least 6 nautical miles from the
start of roll during takeoff. "
ICAO CAN/4-WP/20 (Reference 19) contains the same specifica-
tion; however, in an FAA review (Reference 110) of the CAN/4-WP/20,
the FAA has indicated that the specification should be changed to state
that:
"The position of the aeroplane shall be recorded
relative to the runway for sufficient periods to assure
adequate data on aircraft position during the period
that the noise is within ten (10) decibels of the max-
imum value of PNLT during the takeoff. "
Experience as a result of FAA noise certification tests conducted
since 1969 has shown that the aircraft position data requirement
should be specified in terms sufficient to assure that the aircraft's
position is known during relevant portions of the noise time history
as opposed to over a specific range of the flight paths. Providing
aircraft position data over the relevant period of time as opposed to a
specific portion of the flight path is, in fact, the current acceptable
practice (Reference 114).
Acquiring aircraft position data in strict accordance with the pro-
visions of §A36.1(c)(3) has been most difficult to implement and, in
most cases, such data far exceeds the need for correcting acoustic
5A-9
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data to reference conditions.
The EPA agrees with the FAA in concept and further believes
that the actual practice should be reflected in the regulation. There-
fore, the recommended wording for §A36.1(c){3) is as follows:
(3) The aircraft position along the flight path must be related to
the noise recorded at the noise measurement locations by
means of synchronizing signals over a distance sufficient to
assure adequate data during the period that the noise is within
10 dB of the maximum value of PNLT.
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(C4) Measurements
Experience as a result of FAA noise certification testing conduc-
ted since 1969 has shown that the temperature and humidity measure-
ments procedures should be strengthened to yield more reliable data.
The recommended wording for §A36.1(d)(3) and (4) is as follows:
(3) Acoustic data must be corrected by the methods of §A36. 3(d)
of this Appendix to standard pressure at sea level, an am-
bient temperature of 77 degrees F (25 degrees C), and a
relative humidity of 70 percent. For acoustic data correction
purposes, the test ambient temperature and the test relative
humidity shall be the mean of the samples measured in
accordance with the methods of §A36.1(d)(4) of this Appendix.
Acoustic data corrections must also be made for a minimum
distance of 370 feet (112. 78 meters) between the aircraft's
approach path and the approach measuring point, a takeoff
path vertically above the flyover measuring point, and for dif-
ferences of more than 20 feet (6.10 meters) in elevation of
measuring locations relative to the elevation of the nearest
point of the runway.
(4) Ambient temperature, wind speed and direction, and
relative humidity must be measured in the vicinity of each
of the sideline, takeoff, and approach microphone stations.
The measurements must be made near the surface, at
approximately 100 feet (30.48 meters) above ground, and at
approximately every 100 feet (30.48 meters) of height
5A-11
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thereafter up to and including a height of approximately
1100 feet (335.28 meters) or the reference height of the
aircraft for maximum takeoff noise, whichever is greater.
The mean ambient temperature and mean relative humidity
shall be the arithmetic mean of the height samples, including
the sample taken in the vicinity of the microphone near the
surface. The height of the near surface sensors must be
greater than 2 meters (6. 56 feet) but not greater than 11 meters
(36. 09 feet) above the ground. Instrumentation for and
methods of acquiring atmospheric parameter measurements
must be approved prior to the conduct of the tests.
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D. Measurement of Aircraft Noise Received on the Ground (§A36. 2 of
FAR 36).
(Dl) General.
This section of Appendix A of FAR 36 prescribes the acoustical
measurement system, specifies acceptable characteristics for the
electronic equipment, and identifies the noise measurement proce-
dures. Some, but not all, of the equipment performance specifica-
tions and characteristics were provided by reference to International
Electrotechnical Commission (IEC) publications. Those equipment
characteristics and performance specifications which are not provided
by reference are detailed in various subparagraphs.
The results of noise certification testing conducted since 1969 has
shown that various aspects of the measurement system and electronic
equipment need better definition. Furthermore, improvements in
in electronic equipment have been made and the requirements of this
section should be modified to reflect these advancements.
(D2) Measurement Systein
§A36. 2(b)(l) describes the measurement system as consisting of
five major parts or subsystems as follows:
"(i) A microphone system with frequency response compatible with
measurement and analysis system accuracy as stated in
paragraph (c) of this section.
(ii) Tripods or similar microphone mountings that minimize inter-
ference with the sound being measured.
(iii) Recording and reproducing equipment characteristics,
frequency response, and dynamic range compatible with the
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response and accuracy requirements of paragraph (c) of this
section.
(iv) Acoustic calibrators using sine wave or broadband noise
of known sound pressure level. If broadband noise is used,
the signal must be described in terms of its average and
maximum r.m. s. value for a nonoverload signal level.
(v) Analysis equipment with the response and accuracy require-
ments of paragraph (d) of this section. "
The frequency response of the system (from sensing to reproduction)
is provided by reference to paragraph (c) which limits the applicable
frequency range to that of 45 to 11, 200 Hertz and in turn makes refer-
ence to an early edition of IEC Publication 179 (Ref. 63) which stated:
"...the characteristics of an apparatus for accur-
ately measuring certain weighted sound pressure
levels. The weighting applied to each sinusoidal
component of the sound pressure is given as a
function of frequency by three standard reference
curves, called A, B, C. "
One can assume that the "A" and "B" weighted curves provided in
the reference are not appropriate and that the "C" weighted curve is
the one that is required. That may be what was intended; but, as
evident from the above, the required frequency response characteris-
tics of the sensing/reproduction system are not currently clearly and
definitely specified.
In an attempt to identify other possible substitutes for IEC
Publication 179, the relevant recommended practices of the Society
of Automotive Engineers were investigated. For example, a draft
revision to ARP 796 (Ref. 86) states:
"The response of the complete system to a sensibly
plane progressive sinusoidal wave of constant
amplitude shall lie within the tolerance limits
5 A-14
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specified in ANSI SI. 4-1971 (Type I) over the fre-
quency range 45 to 11200 Hz. "
However, ANSI SI. 4-1971 (Type I) is also a performance specification
for weighted sound level meters and, therefore, is no more useful than
the IEC Publication 179 for this purpose. In addition, this revision to
ARP 796 is still in draft form and therefore does not qualify as a
source of reference in a rule or regulation.
If equipment specifications are to be provided by reference to other
v **
publications, the relative frequency response should not be provided by
reference to specifications for weighted sound level meters but by ref-
ference to specifications for instrument quality sound recording and
reproducing equipment or systems. If this reference cannot be made,
then the specific response of the entire system or parts of the system
should be stated explicitly and listed in the regulation.
From the above discussion, it is evident that paragraph (c) of this
section of Appendix A does not clearly provide the measurement and
analysis system accuracy referred to in §A36. 2(b)(l)(i) nor does it
provide the response and accuracy requirements referred to in
§A36. 2(6)(l)(iii). A similar analysis would show that paragraph (d)
does not clearly provide the analysis system response and accuracy
requirements referred to in §A36. 2(b)(l)(v).
In consideration of the above, the recommended wording for
§A36. 2(b)(l)(i), (iii) and (v) is as follows;
(i) A microphone system with frequency response
characteristics as stated in paragraph (c) of
this section.
5A-15
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(iii) Recording and reproducing equipment with perfor-
mance characteristics as stated in paragraph (c) of
this section.
(v) Analysis equipment with characteristics as stated in
paragraph (d) of this section.
It should be noted that §A36. 2(b)(l)(ii) and §A36. 2(b)(l)(iv) would
remain unchanged and paragraphs (c) and (d) will probably require
modification in order to clearly provide the information indicated above.
5A-16
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(D3) Sensing, Recording and Reproducing Equipment.
This section, §A36.2(c), of Appendix A provides essential perfor-
mance characteristics of certain equipment to be used in sensing,
recording and reproducing the aircraft noise. As it now stands this
section provides a disorganized mixture of recording/reproducing
system characteristics, §A36.2(c)(3) and (5), and system component
characteristics, §A36. 2(c)(l), (2) and (6).
The following discussio'n treats each of the §A36.2(c) paragraphs
in numerical order. The recommended rewording of the entire
§A36.2(c) follows these discussions.
With respect to recording and reproducing equipment, §A36.2(c)(l)
states:
"The sound produced by the aircraft shall be
recorded in such a way that the complete informa-
tion, time history included, is retained. A magnetic
tape recorder is acceptable. "
This paragraph is intended to convey at least two requirements.
First; a magnetic tape recorder, or the equivalent, is required to
make a complete recording of the acoustic signal after being sensed
and conditioned by the microphone/preamplifier equipment. Second;
this recorder mustprovide a mechanism to simultaneously record time
or other information which will allow the acoustic signal to be cor-
related with the aircraft position data.
Experience has shown that; first, there is no reasonable equivalent
substitute for a multiple-channel magnetic tape recorder and, second,
the mimumum performance characteristic of the recorder should be
5A-17
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further specified. With regard to the latter, a draft IEC Publication
(Ref. 108) provides performance specifications for an acceptable tape
recorder system for this purpose.
These include:
"4.1 In any selected 1 / 3-octave frequency range between 112
Hz and 11.2 kHz the amplitude response shall be flat
to within 0. 5 dB, and in any band between 45 Hz and
112 Hz shall be flat within 1 dB.
Note: To meet these tolerances may well require the
use of an F-M tape recorder.
4. 2 The amplitude stability of a 1 kHz sinusoidal signal re-
corded at the standard recording level (i.e. 10 dB below
the 3% distortion level)shall be within+ 0.3 dB through-
out any one reel of magnetic tape, and from day to day
for a given reel of tape at the tape speed used in the
certification test. Measurements to verify this shall
be made using a device with an averaging time equal to
that used in the measuring chain (see §7. 2).
4. 3 The performance of the system must be such that the
background noise in any 1/3-octave band is:
a) at least 45 dB below full scale level,
b) at least 5 dB below the weakest signal level meas-
ured during all the measurement. Only those bands
which contribute more than 0.5% to the total per-
ceived noisiness should be considered.
Note: To help achieve this specification with sharply
falling spectra appropriate pre-emphasis/de-emphasis
networks maybe included. An example of one possible
pre-emphasis curve is shown in Fig. 3. "
In order to be capable of adequately handling an aircraft position
synchronizing signal, the recorder specification should include a
requirement for another recording channel with the provisions for
electrical and physical isolation from the acoustic data channel.
5A-18
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§A36. 2(c)(2) provides the characteristics for the microphone and
amplifier by reference to IEC Publication 179. The inadequacy of this
specification for this purpose was discussed in the previous section
of this report. An acceptable microphone/preamplifier specification
for aircraft noise certification test purposes is proposed in the latest
draft of IEC Publication 29C (Ref. 108).
The IEC recommended microphone system specification includes:
"The microphone must be a pressure-sensitive capacitive type.
In order to obtain the best linear frequency response in the
relevant conditions of measurement, it is recommended that
a pressure response microphone cartridge be used instead of
the normal free-field type. This is because the former has a
near flat response to sound arriving at grazing incidence
(see Fig. 2.).
The variation of microphone and preamplifier sensitivity
within an angle of + 20 ° of grazing (70 c- 110C ) from the nor-
mal through the diaphragm) shall not exceed +_ 2 dB for any
frequency over the range 40 - 12500 Hz. The variation of
microphone sensitivity in the plane of the diaphragm shall
not exceed +_ 0. 5 dB over the same frequency range.
The over-all free-field frequency response at 90° (grazing
incidence) of the combined microphone, preamplifier, wind-
shield, and microphone support shall be determined, using
pure tones at each preferred 1/3-octave frequency from 40
Hz to 12. 5 kHz.
Specifications concerning sensitivity to environmental factors
such as temperature, relative humidity, and vibration shall
be in accordance with the requirements of IEC Publication 179
Precision Sound Level Meters. "
When introduced by Working Group D as a proposed change to ICAO
Annex 16, some delegates to ICAO CAN/4 took objection to this spec-
ification on the basis that it was too restrictive with respect to the
type of microphone that might be used for this purpose. An ICAO
5A-19
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Ad Hoc Working Group has been formed to resolve the issue and report
back to the committee. The issue can be resolved by simply elimin-
ating the first two paragraphs of the above quoted specification and
incorporating the last three paragraphs. Of the last three paragraphs,
the first one provides the required performance characteristics, the
second paragraph provides a procedural requirement, and the last
paragraph provides by reference, adequate environmental considera-
tions.
§A36. 2(c)(3) provides some of the recording and reproducing
system performance specifications and states:
"The response of the complete system to a sensibly
plane progressive sinusoidal wave of constant amplitude
must lie within the tolerance limits specified in IEC Pub-
lication No. 179, over the frequency range 45 to 11, 200 Hz. "
This paragraph does specify the proper frequency band limits
(45 to 11, 200 Hertz) for the system; however, the response tolerances
specified by reference to IEC Publication 179, as previously discussed,
are not adequately specified in this paragraph.
§A36. 2(c)(4) provides a provisional • specification requiring pre-
emphasis and de-emphasis on the recording/reproducing system. This
paragraph states:
"if limitations of the dynamic range of the equipment
make it necessary, high frequency pre-emphasis must
be added to the recording channel with the converse de-
emphasis on playback. The pre-emphasis must be
applied such that the instantaneous recorded sound
pressure level of the noise signal between 800 and 11, 200
Hz does not vary more than 20 dB between the maximum
and minimum one-third octave bands. "
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In view of the spectral distribution of noise produced by many of
the current jet-powered aircraft, the attenuating characteristics of the
atmosphere, and the limited dynamic range of recording systems the
need for high frequency pre-emphasis is properly anticipated.
However, the specification quoted above requires minor modification
to indicate that the less than 20 dB difference is between the maximum
and minimum band levels not the maximum and minimum bands. A
more complete specification would also include a minimum signal-to-
noise ratio for the band containing the minimum signal level.
It should also be noted that, given the high degree of variability
in all of the parameters involved, circumstances may arise wherein
adequate signal-to-noise ratio or pre-emphasis may not be achieved
using standard flight test procedures. This possibility is recognized
by the EPA and, for these cases, a standard alternate flight test pro-
cedure has been recommended in a subsequent section of this report.
§A36. 2(c)(5) states:
"The equipment must be acoustically calibrated using
facilities for acoustic free-field calibration and elect-
ronically calibrated as stated in paragraph (d) of this
section. "
This paragraph does not provide a system or equipment per-
formance specification. However, it does indicate a requirement for a
procedural specification, specifically, calibration. Being procedural
in nature, the essential information in this paragraph and that portion
of paragraph (d) referenced in this paragraph should be inserted in
more appropriate section of the Appendix, §A36.2(e), Noise Measure-
ment Procedures.
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§A36.2(c)(6) states:
(6) A windscreen must be employed with the micro-
phone during all measurements of aircraft noise when
the wind speed is in exc'ess of 6 knots. Corrections for
any insertion loss produced by the windscreen, as a
function of frequency, must be applied to the measured
data and the corrections applied must be reported.
Again, as in the previous paragraph, the information in this para-
graph does not provide a performance specification for a windscreen.
It does however, cover a procedural matter, specifically, under
certain conditions a windscreen must be used and insertion losses
accounted for and reported. Being procedural in nature, the infor-
mation in this paragraph should be inserted in a more appropriate
section of the Appendix. However, since a windscreen is required
under certain circumstances, the characteristics of acceptable wind-
screens for this purpose should be provided in this section.
In view of the above discussions on §A36. 2(c)(l) through §A36. 2(c)
(6), the paragraph requires reorganization and an expansion to include
the essential performance characteristics for the equipment indicated
in §A36. 2(b)(i)and (iii). The following wording is recommended for the
entire paragraph.
§A36.2(c) Sensing, recording and reproducing equip-
ment. (1) Minimum equipment required to sense the
aircraft sound and transform the sound into an electrical
signal suitable for recording on a magnetic tape recorder
will include, a microphone, a microphone support, a
microphone windscreen, a microphone preamplifier and
a microphone ealibrator.
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(i) The variation of microphone sensitivity in the
plane of the diaphragm may not exceed + 0.5 dB,
relative to the sensitivity at 1000 Hertz, over the fre-
quency range of 40 to 12, 500 Hertz.
(ii) The variation of sensitivity of the microphone and
microphone preamplifier combination may not exceed
+_ 2 dB, relative to the sensitivity at 1000 Hertz, within
the angles of 70 to 110 degrees from the axis normal to
the diaphragm (+ 20 degrees about grazing incidence)
over the frequency range of 40 to 12, 500 Hertz.
(iii) The overall free-field frequency response at 90
(grazing incidence) of the combined microphone (including
incidence corrector, if applicable), preamplifier, wind-
screen, andmicrophone support shall be determined using
pure tones at each preferred one-third octave frequency
from 40 Hz to 12, 500 Hz. The frequency response of the
system shall be flat within the following tolerances:
44-3550 Hz + 0. 25 dB
3550-7100 Hz +0.5 dB
7100-11200 Hz +1.0 dB
(iv) Specifications concerning the microphone and
microphone preamplifier sensitivity to environmental
factors such as temperature, temperature gradients,
relative humidity, shock and vibration must be in accord-
ance with those of International Electrotechnical Com-
5 A-2 3
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mission (IEC) Publication 179. The text and specifica-
tions of IEC Publication No. 179 entitled: "Precision
Sound Level Meters", which is incorporated by reference
into this Part, are made a part thereof as provided
in 1 CFR Part 51. This publication was published
in 1965 by the Bureau Central de la Commission
Electrotechnique Internationale located at 1, rue de
Varembe, Geneva, Switzerland, and copies may be
purchased at that place. Copies of this publica-
tion are available for examination at the DOT Library,
the FAA Office of Environmental Quality and at the FAA
Regional Offices.
(v) The microphone windscreeen must be properly
fitted to the microphone, be preferably of plastic foam
or nylon mesh material, and have a diameter not less
than 0. 09 meter (0. 295 feet).
(vi) The microphone/preamplifier combination must
be of such construction as to allow tests and calibrations
to be performed by applying an electrical signal to the
preamplifier and to allow self-noise tests to be per-
formed by substituting an equivalent electrical impe-
dance for the microphone.
(vii) The microphone support and holder must be
of such construction as to provide a minimum of inter-
ference (physical and acoustical) with the microphone
5A-24
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system, tests and calibrations. The holder and support
should be of such construction as to allow easy adjust-
ment to the microphone height and orientation. The
stand should provide steady and secure support for
interconnecting cables in order to minimize noise caused
by wind induced cable motion and vibration.
(viii) A battery powered pistonphone calibrator which
provides a known sound pressure level at a known fre-
quency on the diaphragm of the microphone is required.
Adjustable audio signal generating equipment suitable for
system tests is suggested.
(2) Minimum equipment required to record and reproduce
the transformed aircraft noise signal and aircraft
position synchronization signals will include a multiple -
channel magnetic tape recorder, the aircraft noise
signal preconditioning equipment and, possibly, synchro-
nization signal preconditioning equipment. Depending upon
the particular recorder design, the aircraft noise signal
preconditioning equipment may include pre-emphasis
networks, amplifiers or attenuators.
(i) The magnetic tape recorder amplitude response
at a recording level 10 dB below the 3% distortion level
will be a constant + 0. 50 dB at all band center frequencies
in the one-third octave bands from 180 to 12, 500 Hertz,
and that constant +_ 1. 5 dB at all band center frequencies
in the one-third octave bands from 40 to 163 Hertz.
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(ii) The magnetic tape recorder amplitude stability
of a 1000 Hertz sinusoidal signal recorded at a level
10 dB below the 3% distortion level must remain constant
+ 0. 5 dB throughout the recording of any reel of mag-
netic tape.
(iii) The magnetic tape recorder background noise
level in any one-third octave band shall be 45 dB below
the recording level which causes a 3% distortion.
(iv) Amplifiers or attenuators used to precondition
the aircraft noise signal shall operate in equal integral
decibel steps and the error between the indicated gain
or loss and the actual gain or loss for any setting shall
not exceed 0. 2 dB.
(v) If limitations of the dynamic range of the equip-
ment make it necessary, high frequency pre-emphasis
may be used. Pre-emphasis and de-emphasis networks,
if used, and applied to the aircraft noise signal record-
ing and subsequent playback shall be matched such that
the two networks serially combined shall be constant
+_ 0. 5 dB at each of the band center frequencies for all
one-third octave bands from 40 to 12, 500 Hertz.
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(D4) Analysis Equipment
§A36.2(d) provides specifications for equipment to be used in the
frequency analysis of the recorded airplane noise levels. When FAR
36 was originally drafted, no single referenceable national or interna-
tional standard or specification was available. This situation exists
today. The most recent effort to produce an internationally acceptable
specification for the analysis equipments is incorporated as part of a
draft IEC Document (Ref. 108). This part, as well as other previously
mentioned parts, of that publication are still being reviewed and
evaluated as part of the proposed changes to ICAO Annex 16. On a
national basis, the A-21 committee of the Society of Automotive En-
gineers (SAE)is developing an Aerospace Recommended Practice (ARP
1264, Reference 109) to provide recommended characteristics for the
analysis system. Until the IEC or the SAE documents have gained
further acceptance, neither may be used, by direct reference, in FAR
36. However, selected portions may be extracted and used where it
can be shown to provide an improved definition or specification of the
analysis equipments. Individual paragraphs (specifications) included in
this section are discussed below.
§A36.2(d)(l) and (2), combined, specify that; (1) a one-third octave
band spectral analysis of the acoustic signal must be performed, (2) the
range of the analysis shall include the twenty-four (24) consecutive
one-third octave bands starting at a geometric mean frequency of 50 Hz,
and (3) the filters used for the analysismust comply with the recommen-
dations given in the International Electrotechnical Commission (IEC)
Publication 225.
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The draft IEC publication provides the following specification for
the filters:
"The 1/3-octave band filters shall satisfy the requirements
of IEC Publication 225 and additionally have less than 0.5
dB ripple. In each case the correction for effective band-
width relative to the centre frequency response shall be
determined by measuring the filter response to sine-wave
signals at a minimum of twenty equally spaced frequencies
between the two adjacent preferred 1/3-octave frequencies."
The draft SAE document provides the following specification for
the filters and the performance test of the filters:
"2. 1 Specifications
A set of one-third octave filters to be used for a noise anal-
yzer should contain twenty-four consecutive filters. The
first filter of the set should be centered at 50 Hz, and the
last at 10 kHz. The intermediate center frequencies should
be those specified in the American National Standard SI. 6-
1967, 'Preferred Frequencies and Band Numbers for Acou-
stical Measurements. '
2. 2 Test
It should be demonstrated that the filters in the set meet
the requirements of the following specification:
American National Standard SI. 11, 1966 (Class III)
'Specification for Octave, Half-Octave, and Third-
Band Filter Sets. ' "
A modification to bring FAR 36 in conformance with the draft IEC
publication could be accomplished by changing §A36. 2(d)(2) to include
a statement that each filter shall satisfy the requirements of IEC Pub-
lication 225 and additionally have less than 0.5 dB ripple. This
modification would eliminate undesirable "notches" or low response
in any selected portion of a one-third octave band.
The balance of §A36. 2(d)(3) through §A36. 2(d)(9), provides the per-
5A-28
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formance specifications for the one-third octave band output signal
analyzer. These performance specifications were written to allow the
continued use of a wide variety of analog, digital or combination of
both types of equipments for this purpose. In addition, there is a stated
preferred, but not mandatory, sequence of analyzer operations. This
preferred sequence is; squaring of the one-third octave filter output,
then averaging or integrating, and finally, converting from a linear to
a logarithmic measure of the level.
To continue to allow a wide variety of processes and processors to
be used for this purpose allows the possibility of having a systematic
difference (error) of as much as 1. 5 dB between instrumentation sys-
tems for a constant noise source. With a time varying noise source,
as experienced in aircraft flyovers, the magnitude of the difference
between instrumentation systems is dependent, in part, upon the rate
of change of the level in any sampling period.
Most recent efforts by organizations preparing performance re-
quirements for equipment have not concentrated on the variability
arising from the use of different types of data processors, but appear
to be continuing to try to develop performance specifications and
demonstration tests for a variety of analyzer equipment and processes.
If aircraft flyover measurements and analysis taken at different
test sites and processed by different equipment are expected to be
reliably related to each other, more stringent and restrictive analysis
equipment specifications than currently exist in FAR 36 and any of
the other drafts being considered by SAE or IEC must be developed.
Until these specifications can be developed, improvement in the
5A-29
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FAR 36 specifications related to the analyzer can be achieved by ex-
tracting certain portions of the draft publications on this subject
(Refs. 108, 109 and 65).
In consideration of the above, the recommended wording for
§A36.2(d)(l) through (8) is as follows:
(d) Analysis equipment.
(1) A frequency analysis of the acoustical signal shall be performed
using a set of 24 consecutive one-third octave filters. The first
filter of the set must be centered at a geometric mean frequency
of 50 Hz and the last filter at a geometric mean frequency of 10
kHz. Each filter shall satisfy the requirements of IEC Publica-
tion 225 and additionally, have less than 0. 5 dB ripple.
IEC Publication 225 entitled "Octave, Half-Octave and
Third-Octave Band Filters Intended for the Analysis of Sounds
and Vibrations" is incorporated by reference herein and made a
part of this regulation. This publication is also available at those
places referred to in §A36. 2(c)(l)(iii).
(2) Each of the filtered output signals must be processed to obtain an
indication of the true root-mean-square signal level. The required
sequence of signal processing is squaring of the filter output sig-
nal, then averaging or integrating over a period of time, and then
determining the signal level by converting the averaged or inte-
grated value to a decibel (logarithmic) form.
(3) The indicated output of the signal processor shall be the true root-
mean-square value of the signal level within atolerance of+1.0 dB.
5A-30
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The within tolerance output level may be indicated either directly
or by use of conversion factors derived from calibrations using
nonsinusoidal, time varying signals over the full dynamic range
of the processor.
(4) The analyzer detector or detectors shall operate over a minimum
dynamic range of 60 dB and shall perform, within the specified
tolerances, as true mean square devices for sinusoidal tone bursts
having crest factors of up to 3. Over the range from 0 to 30 dB
below full scale the accuracy shall be within +_ 0. 5 dB; from
greater than 30 to 40 dB below full scale the accuracy shall be
within + 1. 0 dB; at greater than 40 dB the accuracy shall be within
+ 2.5 dB.
(5) If other than a true integrator is used, the standard deviation
of a sample of the detected and integrated output levels of each
detector-integrator shall be 0. 48 +_ 0. 06 dB at a 95 percent con-
fidence level. To demonstrate compliance with this performance
specification the input test signal shall consist of white noise fil-
tered by a one-third octave band filter at a center frequency of
200 Hertz with a statistical bandwidth of 46 + 1 Hertz, and the
detected-integrated output level shall be sampled at intervals of
no less than 5 seconds.
(6) If other than true integration is used, the rise and decay response
to a burst of constant sinusoidal signal at the respective one-
third octave filter center frequencies shall be:
(a) For the rise response the detected-integrated level
5A-31
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shall be -4.00 + 1.00 dB and -1.75 + 0.75 dB below the
steady state level at 0. 50 and 1. 00 seconds after the onset
of the input signal, respectively.
(b) For the falling response the detected-integrated level shall
be such that the arithmetic sum of the decibel reading
(below the steady state level) and the corresponding rise
response reading is -6. 50 + 1. 00 dB at both 0. 50 and 1. 00
seconds after the interruption of the input signal, respec-
tively.
(7) An analyzer using true integration cannot meet the requirements
of paragraphs (5) and (6) of this section. Furthermore, when using
true integration some dead-time may occur during which read-out
and integrator re-setting takes place; in such cases, no more than
5 percent of the total sample time shall be used for this purpose.
(8) The amplitude resolution of the analyzer output must be 0.25 dB
or less.
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(D5) Noise Measurement Procedures.
In addition to those procedures which are currently specified under
§A36.2(e) there are procedural matters in §A36.2(b), (c) and (d), all
of which are system or equipment performance specifications. The
EPA believes that all procedural matters, especially those dealing
with required calibration procedures, should be properly placed in the
regulation; that is, under a section having a procedural title. There-
fore, the EPA should propose to amend §A36.2(e) to include those
matters currently in other sections. Recommended wording for these
additional sections is:
(e) Noise Measurement Procedures.
(1) The microphone must be oriented so that the diaphragm
of the microphone is in the plane defined by the nominal flight
path of the aircraft and the measuring position; that is, with
the aircraft noise arriving at grazing incidence. The micro-
phones must be placed so that their sensing elements are 4. 0
+0.1 feet (1.22 + 0.033 meters) above the ground.
(2) Immediately before and immediately after each series of
test runs and each day's testing, a recorded acoustic calibra-
tion of the system must be made in the field to check the
acoustic reference level for the analysis of the sound level data.
The ambient noise, including both the acoustical background and
the electrical background of the measurement systems, must
be recorded during the period beginning at least 20 seconds
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before and ending at least 20 seconds after each recorded
measurement. During that period, each component of the
system must be set at the gain-levels used for aircraft noise
measurement.
(3) The mean background noise spectrum must contain the
sound pressure levels, which, in each preferred third octave
band in the range of 50 Hz to 10, 000 Hz, are the averages of
the energy during at least 20 seconds of the sound pressure
levels in every preferred third octave. When analyzed in PNL,
the resulting mean background noise level must be at least 20
PNdB below the maximum PNL of the aircraft.
(4) Within the five days before the beginning of each test
series, the complete data acquistion system (including cables)
must be electronically calibrated for frequency and amplitude
by the use of a pink noise signal of known amplitude covering
the range of signal levels furnished by the microphone. For
purposes of this section, a "pink noise" is defined as a noise
whose noise-power/unit-frequency is inversely proportional to
frequency at frequencies within the range of 45 Hz to 11, 200
Hz. The signal used must be described in terms of its average
root-mean-square (rms) values for a nonoverload signal level.
This system frequency response calibration must be repeated
within five days of the end of each test series.
5A-34
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(5) Immediately before and after each day's testing, a re-
corded acoustic calibration of the system must be made in the
field with an acoustic calibrator to check the system sensitivity
and provide an acoustic reference level for the analysis of the
sound level data. The performance of equipment in the system
will be considered satisfactory if, during each day's testing,
the variation does not exceed 0. 5 dB.
(6) For the purpose of minimizing equipment or operator er-
ror, immediately before and immediately after recording air-
craft noise data, field calibrations must be supplemented with
the use of a device to place a known electrical signal at
the input of the microphone.
(7) A normal incidence pressure calibration of the combined
microphone/preamplifier must be performed with pure tones
at each preferred one-third octave frequency from 50 Hz to
10, 000 Hz. This calibration must be completed within the 30
days before the beginning of each test series.
(8) Each reel of magnetic tape must -
(i) Be pistonphone calibrated; and
(ii) At its beginning and end, carry a calibration signal
consisting of a 30 second burst of pink noise, as defined
in paragraph (c)(l) of this section.
(9) Data obtained from tape recorded signals will be considered
reliable if the difference between the pink noise signal levels,
5A-35
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before and after the tests in each one-third octave band, does
not exceed 0. 5 dB.
(10) The one-third octave filters must have been demonstrated
to be in conformity with the recommendations of IEC Publica-
tion 225, dated 1966, during the six calendar months preceding
the beginning of each test series. The correction for effec-
tive bandwidth relative to the center frequency response must
be determined for each filter by measuring the filter response
to sinusoidal signals at a minimum of twenty frequencies
equally spaced between the two adjacent preferred one-third
octave frequencies.
(11) A performance calibration analysis of each piece of cali-
bration equipment, including pistonphones, reference micro-
phones, and voltage calibration devices, must have been
made during the 12 calendar months preceding the beginning
of each day's test series. Each calibration must be traceable
to the National Bureau of Standards.
(12) The analysis equipment required under paragraph (d) of this
section must be subjected to a frequency and amplitude electrical
calibration by the use of sinusoidal or broadband signals at fre-
quencies covering the range of 45 to 11, 200 Hz, and of known
amplitudes covering the range of signal levels furnished by the
microphone. If broadband signals are used, they must be des-
cribed in terms of their average andmaximum rms values for a
nonoverload signal level.
5A-36
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E. Reporting and Correcting Measured Data (§A36. 3 of FAR 36).
(El) General
§A36. 3(a) provides a general statement requiring that all data ac-
quired from physical measurements be provided in permanent form
and appended to the certification records. It also requires that an
estimate of "individual errors inherent in each of the operations em-
ployed in obtaining the final data" be made. Neither the purpose,
extent, nor methodology for this last requirement are explicit. If the
purpose is to provide a qualitative assessment of the overall accuracy
of the test procedures, then a more explicit statement of the items
or operations to be evaluated and the allowable tolerances on their
measurement should be specified. If no specific use of this assess-
ment is to be made, then the requirement should be deleted.
5A-37
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(E2) Data Reporting
§A36. 3(b) provides a specific list of noise data, aircraft param-
eters, and meteorological data to be supplied in the certification test
report. With the exception that it does not require EPNL values to be
reported (in this section, at least) the existing text is satisfactory in-
sofar as its inclusion of basic parameters is concerned. It does not
require reporting of reference flight paths to be used in A36. 3(d), and
should be amended to do so.
A more serious deficiency is the lack of a requirement to report
data that can be used to derive information for noise produced at other
than the specified three measurement locations or for other than
maximum aircraft weight conditions. Further, these data need to be
supplied in a format suitable for planning purposes.
The Administrator of the EPA, under authority granted in the Noise
Control Act of 1972 (Public Law 92-574), has announced to all federal
agencies (Reference 112) his intention of specifying a standard measure
to be used to describe the magnitude of community noise exposure lev-
els. In his announcement the Administrator indicated that the Agency
intends to specify the use of either the Equivalent Sound Level (Leq)
or, as appropriate, the Day-Night Level (Ldn).
In view of this announced intention, it is assumed that where
measurements or estimates of community noise exposure levels are
required for planning or regulatory purposes one or both of these
measures will be required. Both measures are based upon the time-
integrated mean square A-weighted sound level. Where direct meas-
5A-38
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urements of community noise exposure levels resulting from existing
operations are concerned, no extraordinary problems are expected.
However, where estimates or predictions of community noise exposure
levels resulting from future, or otherwise hypothesized, operations
are concerned, reliable results may not be obtained without a reason-
able knowledge of each individual source's noise characteristics.
These characteristics include the source noise level (appropriately
weighted) as a function of the source's operational mode, the distance
between the source and the community, and the intervening sound
propagation path. For aircraft, because of the wide variation in each
of these influencing parameters, this requirement represents a com-
prehensive set of noise tables and related operational data. However,
previous and on-going programs within the USAF, FAA, NASA, and
EPA to develop aircraft noise estimating methods have resulted in
some methods which can be used to derive the required comprehensive
set of tables from a fairly small and simple set of noise measure-
ments and aircraft performance characteristics. All of the necessary
basic information and data are either used or obtained in the ordinary
conduct of a noise certification program as currently prescribed by
FAR 36. However, in order to make the basic information and data
routinely available and more useful to the public, the reporting
requirements of §A36. 3(b) will require modification.
Aircraft noise and operating data should be reported for the fol-
lowing three flight conditions:
1. Certification takeoff conditions, as measured at 3.5
nautical miles from the start of takeoff roll on the
5A-39
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extended centerline of the runway, or alternate (a)
below. Alternate (a) must be used if the aircraft height
at the 3. 5 nautical mile point exceeds 2000 feet.
(a) Horizontal flight, with aircraft height of 1000 feet,
takeoff thrust, and V2 +10 knots airspeed at maximum
takeoff weight.
2. Horizontal flight, with aircraft height of 1000 feet,
maximum climb thrust, V2 + 10 knots airspeed, at max-
imum takeoff weight.
3. Certification approach conditions, as measured at a
point 1 nautical mile from the runway threshold on the
extended centerline of the runway.
Data should be obtained from certification tests but are to be ad-
justed to reference day conditions (77 degrees F, and 70% relative
humidity at sea level).
For each of the three conditions specified above, the following data
are to be provided:
1. Aircraft height, ft.
2. Engine net thrust, Ibs. (Note 1).
3. Airspeed, knots.
4. Flap settings, degrees.
5. Ratio of Lift to Drag Coefficients (Cl/Cd). (Note 2).
6. Effective perceived noise level (EPNL), EPNdB.
7. Sound exposure level (SEL), SEdB (Note 3).
8. Maximum perceived noise level (PNLM), PNdB.
5A-40
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9. Maximum tone-corrected perceived noise level (PNLTM), PNdB.
10. Maximum A-level (ALM), ALdB.
11. Angle of noise radiation from aircraft at time of PNLM, (i),
degrees (Note 4).
12. Angle of noise radiation from aircraft at time of ALM, (412 ),
degrees (Note 4).
13. One-third octave band sound pressure levels (SPL) on ground
at time corresponding to i, dB.
14. One-third octave band SPL on ground at time corresponding to
2, dB.
Note 1. In order to interpret aircraft operational procedures executed
by pilots using cockpit instrumentation, information is to be provided
to relate engine power or thrust with the primary power setting para-
meter used by the pilot. For turbojet or turbofan aircraft, this re-
quirement can be met by charts or tables showing the relation between
net thrust and engine pressure ratio (EPR) or fan speed (N).
Note 2. Ratio of lift to drag coefficients for zero flap and all other
flap positions certified for takeoff, approach and /or landing with and
without gear down should be reported.
Note 3. The sound exposure level (SEL), in dB, is the level of the
time-integrated mean square A-weighted sound pressure for an event,
with a reference time of one second:
SEL = 10 log ant(AL/10)dt (1)
5A-41
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For planning purposes the aircraft noise evaluation unit, SEL, is to be
computed from A-levels sampled at discrete intervals of 0. 5 seconds
or less over the time interval d (in seconds) during which theA-level is
within 10 dB of the maximum A-level (ALM). Thus the working express-
ion for SEL becomes:
SEL = 10 log } ant[AL(k)/10] (2)
L — i
k=l
where At is the time interval (in seconds) between noise level samples.
Note 4. Directivity angles, 1 and 4>z, are to be determined by taking
into account both aircraft speed and sound propagation speed. The
angles may be calculated by:
sin 4> = h(l-v2/c2) cos Y
~[K COS Y)2ll-V2/C2)+(vT)2]l 2-V^tTc (3)
where h = aircraft height, ft.
v = aircraft true airspeed, ft/sec
c = speed of sound, ft/sec
9 = climb angle, degrees
t = interval between time of aircraft passing overhead and time of
maximum noise level (PNLM and ALM), sec.
5A-42
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§A36. 3(c) defines the reference conditions to which all test results
must be corrected. §A36. 3(c)(l) defines the meteorological reference
conditions and there is no need to change those which are specified.
§A36. 3(c)(2) defines the aircraft reference weight conditions for take-
off and landing and the reference approach flight path and there is no
need to change those which are specified.
5A-43
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(E4) Data Corrections
§A36. 3(d) provides for the process of correcting test conditions to
reference conditions in accordance with §A36. 6.
§A36. 3 (d)(3) specifies that corrections in measured sound
pressure levels shall be made if they do not exceed the background
(ambient) levels by at least 10 decibels. A number of possible methods
for making these corrections have been advanced by different technical
groups, including the ICAO CAN working groups. No method has
achieved general acceptability at this time. It seems appropriate that
the existing text be retained until such time as a generally acceptable
method has been adopted by an appropriate technical body or standards
activity.
5A-44
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F. Symbols and Units (§A36. 4 of FAR 36).
(P1) General.
§A36. 4 of Appendix A of FAR Part 36 provides a listing of all
symbols, the physical units and meaning of all symbols used in Appendix
A and B of "Part 36. Additional symbols, units and definitions will be
required in order to accommodate a discussion or specification of the
additional reporting requirements and/or approved alternative proce-
dures. These will be extracted from this report and tabulated as a
proposed revision to §A36.4.
5A-45
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G. Ajmospheric Attenuation of Sound (§A36. 5 of FAR 36).
(Gl) General.
Corrections to sound spectra are required when atmospheric con-
ditions differ from the specified reference conditions. §A36.5 provides
two methods of determining the atmospheric attenuation of sound for a
variety of ambient temperature and relative humidity conditions. One
method is that provided by reference to certain portions of the Society
of Automotive Engineers (SAE) Aerospace Recommended Practice (ARP)
866; the other, a simplified method, is presented in detail in §A36. 5.
The simplified method was introduced as an alternative in cases or
situations where computer assisted computations were not practicable
or feasible. This situation however has proven to be rare and has
rendered the simplified method, for practical purposes, of no value.
The SAE ARP 866 has recently undergone substantial revision to make
itmore useful, especially in computer assisted processes and analyses.
In view of the above, consideration should be given to specifying
only one method of determining the atmospheric attenuation; that is,
the method provided in SAE ARP 866A as revised in March 1975. This -
will require changing §A36.5(a) and the elimination of paragraphs
§A36.5(b) and (c) including the referenced Figure therein.
The recommended rewording of §A36. 5(a) is as follows:
(a) General. The atmospheric attenuation of sound must be
determined using the atmospheric absorption coeffecients
5A-46
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for one-third octave bands of noise as presented in
Table 2 of Appendix B of SAE ARP 866A as revised in
March 1975. SAE ARP 866A is an Aerospace Recom-
mended Practice published by the Society of Automotive
Engineers entitled: "Standard Values of Atmospheric
Absorption as a Function of Temperature and Humidity".
The recommended atmospheric attenuation coeffecients
as provided therein are incorporated by reference into
this Part and are made a part hereof as provided in
1 CFR Part 51. This publication is published by
the Society of Automotive Engineers, Inc. located
at 400 Commonwealth Drive, Warrendale, Pa. , 15096,
and copies may be purchased at that place. Copies of
this publication are available for examination at the
DOT Library, the FAA Office of Environmental Quality
and the FAA Regional Offices.
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H. Detailed Correction Procedures (§A36. 6 of FAR 36).
If the noise type certification test conditions are not equal to the
noise type certification reference conditions, corrections must be
made to the value of EPNL calculated from the measured data. The
type of corrections and the methods of applying these corrections are
detailed in §A36. 6 of Appendix A of Part 36.
The present text of §A36. 6(a) provides a general discussion of
corrections for atmospheric absorption, flight paths different from
reference, and test weights less than maximum. No discussion is
provided for the effect of test day thrust being different than
reference thrust, or the effect of test airspeed being different than
reference airspeed. Further, the discussion of the effect of weight
corrections is not easily related to the physical situation and ex-
perience has shown it to be impractical to implement. Therefore,
modifications to certain parts of §A36. 6 are required in order to
provide practical and meaningful methods of accounting for differences
in reference and test conditions; not only for atmospheric absorption,
flight paths and weights, but also for thrust and airspeed.
The proposed modifications include: (1) changing the general dis-
cussion of §A36. 6(a) which is introductory and explanatory in nature,
(2) changing the discussion and method of atmospheric absorption
correction procedures in §A36. 6(d) to provide for corrections to be
made by either one or two methods, depending upon test atmospheric
conditions, (3) changing the discussion and method of duration cor-
rections provided in §A36. 6(e) to provide for a correction in duration
5A-48
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due to differences in reference and test airspeeds and (4) deleting
the discussions and methods of providing weight and approach angle
corrections of §A36. 6(f) and (g), respectively, and (5) substituting a
discussion and method of applying corrections for differences in
reference and test thrust.
Paragraphs A36. 6(b) and (c) discuss the structure of takeoff and
approach profiles, respectively, and the geometrical relationships
between reference and test profiles for each of these operations.
These paragraphs include references to Figures A2 through A7. The
text and nomenclature in these sections and figures are clear and
unambiguous and there appears to be no need for any change in either
paragraph.
A36. 6(e) describes a correction for effective duration based on the
difference in slant distance to the aircraft from the ground position
between test and reference conditions. In addition to this correction,
allowance for difference in true airspeed, V, between test and
reference conditions (Vt and Vr) should be applied. The modified
expression for A 2 under takeoff conditions should be:
A 2 = -10 log (KR/KRc). (4)
For approach conditions, the expression should be:
A 2 = -10 log (NT/369). (5)
No duration correction is presently specified for the sideline measure-
ment. An airspeed correction should be made in the same manner as
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for takeoff and approach. The appropriate expression is:
A 2 = 10 log (Vt/Vr) (6)
Note that the reference true airspeeds for takeoff and sideline meas-
urements are likely to be slightly different in that they will most
likely occur when the aircraft is at different heights. It is accepted
practice to perform tests at a constant indicated airspeed, which thus
results in a difference in true airspeed as a function of height due to
the decrease in atmospheric density with height.
A36.6(f) states that corrections for aircraft weight are to be ap-
plied, based on "approved data... as indicated in Figures A8 and A9. "
No discussion is provided as to how such data are to be obtained. A
similar form of correction is specified in A36.6(g) for approach angle
corrections. In practice neither of these corrections, as specified,
is really useful.
There is no question that corrections need to be made for the ef-
fect of different aircraft weights. Just as clearly, a correction for
the effect of thrust different than reference thrust needs to be made.
From an acoustical viewpoint, the noise on the ground is specified by
distance to the aircraft, aircraft height, airspeed, and engine power/
thrust. Similarly from a performance viewpoint, variation in the posi-
tion of the aircraft (in a fixed configuration) with time is a function
of weight, net thrust, airspeed, and lift/drag ratios.
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The geometric effects on sound pressure levels due to weight,
power, and airspeed are completely accounted for in the corrections
made for differences in flight paths and in duration corrections due
to airspeed differences. The remaining acoustical effect is the
variation in acoustical power radiated at different engine power
settings. This correction can be derived from noise measurements
obtained from a series of level flyovers in which EPNL is determined
as a function of engine power (described in terms of referred net
thrust or referred fan rotor speed) when normalized to reference air-
speeds and heights.
It is recommended that A36.6(f) and (g) be replaced with a correc-
tion procedure that properly accounts for variations between test and
reference power/thrust conditions, based on data derived from speci-
fied flight tests.
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I. Aircraft Noise Evaluation Under Section 36.103 (§B36.1 of FAR 36)
I. General.
Appendix B specifies the detailed procedures and standards to
be used to determine a single-number, noise evaluation quantity
designated as Effective Perceived Noise Level (EPNL). This measure
is derived from analysis of a specified portion of each of the
filtered and corrected time-data samples of the noise. The required
procedure includes the following, where the symbol "(k)" refers to
the k-th time data sample:
"(a) The 24 one-third octave bands of sound pressure level are con-
verted to perceived noisiness by means of a noy table. The
noy values are combined and then converted to instantaneous
perceived noise levels, PNL (k).
(b) A tone correction factor, C(k) is calculated for each spectrum
to account for the subjective response to the presence of the
maximum tone.
(c) The tone correction factor is added to the perceived noise level
to obtain tone corrected perceived noise levels, PNLT(k), at
each one-half second increment of time. The instantaneous
values of tone corrected perceived noise level are noted with
respect to time and the maximum value, PNLTM, is determined.
PNLT(k) = PNL(k) + C(k)
(d) A duration correction factor, D, is computed by integration
under the curve of tone corrected perceived noise level versus
time.
(e) Effective perceived noise level, EPNL, is determined by the
algebraic sum of the maximum tone corrected perceived noise
level and the duration correction factor.
EPNL = PNLTM + D"
Each step in the above described process, including a mathematical
formulation of the noy tables, is detailed in a separate paragraph of
5B-1
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Appendix B. Under 1 CFR Part 51, information such as this detailed
computational procedure and the associated tables and formulas may
be provided by reference to a readily available and maintained docu-
ment. Referenceable sources of the material covered in Appendix B
might include either the appropriate sections of Appendix 1 of the
International Civil Aviation Organization's (ICAO) Annex 16 or the
appropriate Aerospace Recommended Practices (ARPs) of the Society
of Automotive Engineers (SAE) or an appropriate recommendation or
standard of the American National Standards Institute (ANSI).
On July 10, 1973, the ANSI approved, as S6. 4-1973, the June 1972
version of the SAEARP1071 entitled "Definitions and Procedures for
Computing the Effective Perceived Noise Level for Flyover Aircraft
Noise". The June 1972 issue of SAE ARP 1071 was later edited and
revised in October 1973.
Therefore, the detailed material provided in Appendix B could
be eliminated entirely by inserting the necessary reference to SAE
ARP 1071. Such a proposed amendment to Part 36 would not only
simplify the regulation but provide specific reference to a nationally
accepted standard and practice. The recommended wording to ac-
complish this change is as follows:
§B36.1 General.
The physical properties of the noise measured and
corrected as prescribed by Appendix A of this Part are to
be used to determine the noise evaluation quantity designated
as effective perceived noise level, EPNL. The definitions
5B-2
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and procedures for determining EPNL shall be those pro-
vided in the Society of Automotive Engineers' Aerospace
Recommended Practice (SAE ARP) 1071 as revised in October
1973. This publication entitled: "Definitions and Procedures
for Computing the Effective Perceived Noise Level", and
other SAE publications by reference therein, are incorpor-
ated by reference into this Part and are made a part thereof
as provided in 1 CFR Part 51. This publication was
published in October 1973, by the Society of Automotive
Engineers, Inc., located at 400 Commonwealth Drive,
Warrendale, Pa. , 15096, and copies may be purchased at
that place. Copies of this publication are available
for examination at the DOT Library, the FAA Office of
Environmental Quality and the FAA Regional Offices.
Additional comments on subdivisions of Appendix B material as
it currently exists in FAR 36 and improvements incorporated in SAE
ARP 1071 are provided in the following paragraphs of this report.
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J. Perceived Noise Level (§B36. 2 of FAR 36).
The general principles of an internationally accepted three-step
method of determining the perceived noise level, PNL, from a set of
24 one-third octave band sound pressure levels are outlined in FAR 36,
§B36.2; in Appendix I, ICAO Annex 16, Paragraph 4.2; and in SAE
ARP 865A.
Step 1 of the method presented in each of the documents refers
to tabulated perceived noisiness (noy) values which are, in turn, based
upon referenced formulations. Further discussion of the differences
in the referenced noy tables and the formulas upon which they are
based is provided in Section "O" of this report. Except for matters
concerned with presentation of noy formulas or tables, the only
material difference between the three documents is in the third step
of the method. Both FAR 36 and ICAO Annex 16 state:
"Step 3. Convert the total perceived noisiness, N(k), into
perceived noise level, PNL(k), by the following formula:
PNL(k) = 40. 0 + 33. 3 log N(k)".
The method outlined in ARP 865A for Step 3 states:
"N is converted into perceived noise level (PNL) in PNdB
by the following expression:
PNL = 40 + 33.22 log N".
The most recent report of the ICAO Committee on Aircraft Noise
(CAN 4) recommends that the formula in Step 3 of Paragraph 4. 2 of
Appendix I to Annex 16 be changed to read as follows:
"PNL(k) - 40. 0 + [(10/log 2)log N(k)j".
5B-4
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Since the quantity 10/log 2 - 33.22, to the nearest one-hundreth, it
appears that is what was intended in ARP 865A, and that Step 3 of
FAR 36 §B36. 2 will also require modification.
To correct the above discussed error, the following formula for
Step 3 under §B36. 2 is recommended:
PNL(k) = 40.0 + 33. 2 log N(k). (7)
This error would also be corrected by replacing the entire Appen-
dix B material with SAE ARP 1071, since this ARP makes use of ARP
865A for the computation of PNL and is included by reference therein.
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K. Correction for Spectral Irregularities (§B36. 3 of FAR 36).
The presence of tonal components in aircraft and other sources of
noise has been determined to have the effect of increasing the annoyance
caused by the noise. A 10-step method of determining the possible pre-
sence of tonal components by examination of a one-third octave band
spectrum of the noise and an adjustment to the corresponding PNL was
developed and the details are provided in §B36. 3 of FAR 36. This
method, which was essentially duplicated in Appendix 1 of ICAO
Annex 16, was derived from a working draft of SAE ARP 1071. Experi-
ence with this method 'has shown that its use can produce anomalous
"pseudotones" in certain cases, and can not properly account for tonal
components that appear in contiguous frequency bands. For these
reasons the SAE, after the promulgation of FAR 36, continued work to
develop an improved method. This effort resulted in the 7-step pro-
cedure of ARP 1071 which was approved by the SAE and first issued
in June 1972. These procedures were revised by SAE and submitted
to the American National Standards Institute. The document was
subsequently published as ANSI S6.4-1973 (Ref. 110). The EPA was
notified of these actions by the SAE A-21 Committee on Aircraft
Noise in July 1974 (Ref. 111).
The method of accounting for spectral irregularities currently in-
corporated in FAR 36 and Annex 16 and the method approved by the
SAE and ANSI differ in two ways. One is the method of smoothing
and examining the spectrum to identify irregularities, and the other
is in the tone penalty for Level Differences (F) of less than 3 dB.
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Recently, during the fourth meeting of the ICAO Committee on
Aircraft Noise (CAN/4), Working Group D recommended a modifica-
tion in the Annex 16 method which would have incorporated one of
the features of the SAE/ANSI procedure. The recommended change
would eliminate the Annex 16 practice of ignoring the Level Differ-
ences (F) of less than 3 dB when determining the Tone Correction
factor (C). The practice was originally incorporated in order to avoid
extraordinary difficulties with what are known as "psuedo-tones" (spec-
tral, discontinuities caused by phenomena other than, or in addition
to, tones in the source noise, particularly, those caused by ground
plane reflections). The Working Group D recommendation to change
Annex 16 met with considerable opposition by some delegates,
including the United States. An ICAO Ad Hoc Working Group has
been formed to resolve the issue on this recommendation and re-
port back to the committee.
The latest report of the ICAO Committee on Aircraft Noise
(Ref. 35 )indicates that the committee is recommending a modification
of Annex 16 which will incorporate the treatment of Level Differences
of less than 3 dB as provided in the SAE/ANSI procedure.
Since the ICAO CAN 4 meeting, the SAE A-21 Committee, at the
specific request of the FAA Office of Environmental Quality, has
begun a reexamination of its ARP 1071.
However, on the basis that the new and improved method has been
scrutinized within several standards groups, representing the aircraft
industry as well as a wide segment of other opinions, it is unlikely
5B-7
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that the SAE and ANSI will either: (1) find substantial technical
reasons to retrogress and approve the method as currently provided
in FAR 36 or (2) easily or quickly, develop a further improved method
for this purpose.
In view of the above, it is concluded that (1) the 7-step procedure
of SAE ARP 1071 (ANSI S6. 4-1973) provides a more efficient analysis
of the tonal components in aircraft noise, and (2) there are no signi-
ficant differences between the 7 and 10-step procedures in evaluating
annoyance (or any other health and welfare effects) caused by the
tonal components. It is recommended, therefore, that §B36. 3 of
FAR 36 be amended to incorporate SAE ARP 1071 (ANSI S6. 4-1973) by
reference.
5B-8
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L. Maximum Tone Corrected Perceived Noise Level
(§B36.4 of FAR 36).
§B36. 4 defines the maximum tone corrected perceived noise level
as the maximum value of the tone corrected perceived noise level cal-
culated in accordance with the procedure of the previous section,
§B36. 3, of this Appendix. An illustrated example of the determination
of the maximum tone corrected perceived noise level is also provided
in this paragraph. There is no need to change this section of Appendix
B if it is retained.
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M. Duration Correction (§B36. 5 of FAR 36).
The duration of a noise event has been demonstrated to be one of
the characteristics of noise associated with annoyance. Therefore, a
measure of the noise duration is included in the computation of EPNL.
The method by which the duration correction factor, D, of EPNL is
currently determined is specified in §B36. 5 of Part 36, Appendix B.
The method is dependent upon a determination of the time period,
d, during which the tone corrected perceived noise level (PNLT) is
within 10 decibels of the maximum tone corrected perceived noise
level (PNLTM). This method appears to be reasonable except that
the method also states: "if the value of PNLT (k) at the 10 dB-down
point is 90 PNdB or less, the value of d may be taken as the time
interval between the initial and the final times for which PNLT(k) equals
90 PNdB. " By so allowing a 90 PNdB limit (or "floor") to be used in
determining the duration factor, a false and misleading measure of
the duration of the noise, and therefore, a false and misleading meas-
ure of the EPNL is determined and reported. This deficiency in
determining the duration correction factor may be corrected by simply
eliminating the 90 PNdB floor.
In practice, other relatively minor difficulties in determining the
proper duration correction factor using the currently specified method
have been noted. For instance, the duration time, d, is specified to be
the "time interval to the nearest 1.0 second." Since PNLT(k) values
are calculated for time increments of 0. 5 second, no apparent purpose
is served by restricting the duration to an even number of half-seconds.
5B-10
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The more appropriate duration could be determined to the nearest 0. 5
second. Also, the method specifies that if the 10 dB-down points fall
between calculated PNLT(k) values, the applicable time history limits
must be chosen from the PNLT(k) values "closest" to the 10 dB-down
threshold. When this requirement is combined with the foregoing re-
striction to an even number of samples, a rather inexact determination
of the real duration may be made.
The "significant noise time history" is defined as that portion of
flyover during which PNLT(k) is within 10 dB of PNLTM. Values
below the 10 dB-down threshold could reasonably be considered insig-
nificant, and always be excluded. Or, since, in fact, these points
contribute only slightly to the calculated duration correction factor,
the closest point below the threshold at each end of the flyover noise
recording could always be included. Sample calculations indicate
that, on the average, the latter procedure provides a closer approxi-
mation to the real answer than the former. It is probable that, at
a slight increase in complexity, an even closer approximation to the
real answer can be obtained by using both of the foregoing rules -
one at each end of the time history. For example, at the initial thres-
hold crossing, the point at or immediately below the threshold would
be used as the initial value, while at the final threshold, the
point at or immediately above the threshold would be used as the
final value. Appropriate language might be: "if a 10 dB-down point
falls between two calculated PNLT(k) values (the usual case), the value
preceding the threshold crossing should be chosen as the limit for
the duration time. "
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Also, there appears to be a need to clarify the method and pro-
cedures to be used when the noise time history of PNLT contains more
than one excursion above the 10 dB-down threshold. This is a situation
that can occur often with moving sources having both forward and aft
noise directive characteristics.
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N. Effective Perceived Noise Level (§B36. 6 of FAR 36).
§B36. 6 defines the effective perceived noise level as being the
algebraic sum of the maximum tone corrected perceived noise level
and the duration correction as calculated under §B36.4 and §B36. 5,
respectively. There is no need to change this section of the Appen-
dix B if it is retained.
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O. Mathematical Formul'ation of Noy Tables (§B36. 7 of FAR 36).
§B36. 7 provides a method of computing the perceived noisiness
or noy, n, values listed in Table Bl (referred to in §B36. 2). Except
for some errors and a slight rearrangement of some of the material,
Paragraph 7 of ICAO Annex 16, Appendix 1 is identical to this section
of FAR 36. Both the FAR 36 and the ICAO material appear to have
been derived as limited cases (noy, n""1.0 and level, SPI>150) of
the more general case (noy, n?0.1 and level, SPL-150) provided in
ARP 865A.
In considering changes to this part of Annex 16, the most recent
report of the ICAO Committee on Aircraft Noise (CAN 4) recommends;
(1) correcting the errors inherited from FAR Part 36, (2) correcting
the errors in the original Paragraph 7, and (3) expanding the noy tables
to provide noy values below 1. 0 and those noy values for SPL — 140
and frequencies above 1000 Hertz which were not included in any of the
original (ARP 865A, FAR 36 and Annex 16) tables. However, while
the ICAO CAN-4 recommendation provides expanded noy tables, the
recommended modifications to Paragraph 7 do not include the com-
putational method for the additional values where O.l£ n < 1. 0. Since
the tabulated noy values for 0.1 ± n < 1. 0 and the method to be used
to calculate these values are provided in ARP 865A, this document
remains the most complete and error free reference for tabulated noy
values and procedures for computing these values.
A rather major modification would be required to provide this same
information in §B36. 7. It would include providing the equations and
expanding the table of constants (Table B4 of §B36. 7) to allow the
5B-14
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computation of noy values when 0.1 £ n £ 0. 3 and 0. 3 <. n <. 1.0 and
providing the additional noy values in Table Bl of § 36. 2.
All of the above can be accomplished most simply by incorporating
SAE ARP 865A by reference, either directly or through the use of SAE
ARP 1071 (ANSI S6. 4-1973) as a substitute for the entire Appendix B.
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P. Noise Measurement and Evaluation (§C36. 1 of FAR 36).
Appendix C of FAR 36 specifies the noise measuring points and the
airplane takeoff and approach test conditions that must be maintained
to achieve the compliance noise levels. §C36. 1 of FAR 36 simply
states that:
" Compliance with this Appendix must be shown with
noise levels measured and evaluated as prescribed, re-
spectively, by Appendix A and Appendix B of this Part
or under approved equivalent procedures".
The above wording is not clear in regard to approved equiv-
alent procedures applicable to Appendix C. Approved equivalent test
procedures (including location of measuring points and takeoff and
approach test conditions) have at times been necessary or convenient
to the Government and type certificate applicant. Therefore, the word-
ing of §C36. 1 should clearly indicate that approved equivalent proce-
dures are permitted in Appendix C when demonstrated to be necessary.
The recommended wording for §C36. 1, therefore, is as follows:
Compliance with this Appendix must be shown with
noise levels measured and evaluated as prescribed, re-
spectively, by Appendix A and Appendix B of this Part,
or under approved equivalent procedures. Approved
equivalent procedures may also be permitted for compli-
ance with the procedures of this Appendix.
In order to insure consistent results, amendments made to this appendix
5C-1
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should include specifications which would standardize equivalent test
procedures wherever the need can be identified.
Furthermore, this appendix should be amended so far as feasible
to insure that results of the noise certification testing would be useful
for analyzing community noise impact and for land use planning.
Takeoff and approach test procedures should yield results that are
compatible with normal safe airplane operations. This requirement
does not mean that the test procedures specified in Appendix C (or
approved equivalent) may not deviate from normal operations for spe-
cific airplanes. Standards (including test procedures) applicable to
a wide variety of airplanes, having a large range of noise levels, are
designed to insure that all airplanes are tested in a consistent and
fair manner. The standards in FAR 36 cannot be expected to (and
need not) duplicate exactly the preferred or normal operating conditions
for each airplane, nor yield the exact noise levels for those normal
conditions. However, the standards should include correction techni-
ques so that the measured noise levels, if not directly applicable,
can be adjusted to be representative of normal operating conditions.
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Q. Noise Measuring Points (§C36. 3 of FAR 36).
§C36. 3 of FAR 36 specifies that the compliance noise levels must
be achieved at the following measuring points:
"(a) For takeoff, at a point 3. 5 nautical miles from the start
of the takeoff roll on the extended centerline of the
runway;
(b) For approach, at a point 1 nautical mile from the thresh-
old on the extended centerline of the runway; and
(c) For the sideline, at the point, on a line parallel to and
0. 25 nautical miles from the extended centerline of the
runway, where the noise level after liftoff is greatest,
except that, for airplanes powered by more than three
turbojet engines, this distance must be 0. 35 nautical
miles. "
5C-3
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(Ql) Takeoff
Experience as a result of noise certification since 1969 has shown
that the measuring point for takeoff (3. 5 nautical miles from brake
release) is satisfactory for determining noise levels which are pro-
duced by relatively noisy airplanes. However, for airplanes which
have substantial applications of noise control technology and/or have
relatively large takeoff climb angles, significant portions of the spec-
trum of the noise signal received at the 3.5 nautical mile point may
be masked by normal background noise at the test site. For these
cases FAR 36 permits FAA approved "equivalent procedures" which
generally have been those proposed by the manufacturer and approved
on a case-by-case basis. This practice has merit, but an approved
equivalent procedure which may be reasonable for a particular airplane,
may not permit valid comparisons to be made with other airplanes
and/or other procedures.
To insure consistent results, an equivalent test procedure should
be standardized for those airplanes whose noise measured at the takeoff
point would not be reliable because signal to noise ratios (S/N) are too
small. Such an amendment to FAR 36 would be particularly appropriate
at this time because application of current, available, and future
technology should result in significantly lower noise levels for new
type design airplanes.
Two procedures would solve the S/N problem and could be standard-
ized. The first would be to have an alternate noise measuring point
located nearer to the runway. The microphone, therefore, would be
nearer to the airplane flight path thus increasing the signal to noi^e
5C-4
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ratio. The second procedure would be to retain the standard dis-
tance (3. 5 nm from brake release or approved equivalent) but change
the flight procedure so that the airplane flight path would be nearer
to the microphone. Both procedures have merit but the second one
has a precedent established for propeller driven small airplanes and
is the preferred "equivalent procedure" for the reasons identified
below. Also, both procedures would require additional analyses of
the data and the development of correction techniques.
Small propeller airplanes are now required to demonstrate com-
pliance with the noise level requirements of Reference 15 by means
of horizontal flights over a noise measuring station at a height of 1000
ft. The noise levels determined by means of the 1000 ft horizontal
flight procedure are corrected for climb performance. The correction
formula yields a level in decibels which, when added algebraically to
the measured noise level at 1000 ft (horizontal flyover), approximates
the noise level at a specified reference distance from brake release.
The EPA proposal (References 117 and 118) to amend the current pro-
peller noise regulations (Reference 15) supports the 1000 ft horizontal
flight procedure, but proposes a revised correction formula based
upon both climb performance and speed. Since the precedent has been
established, it is reasonable to extend the horizontal flight procedure
to all airplanes which cannot be measured reliably at the 3. 5 nm
point.
Another reason for using the horizontal flight procedure (as op-
posed to an alternate measuring point) is that it is more convenient.
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The preferred test procedure for demonstrating compliance with the
takeoff noise level requirement is for an airplane to execute its nor-
mal takeoff and climbout procedures with the microphone at 3.5 nm
from brake release. All airplanes should perform this procedure at
least once. In most cases the signal to noise ratio can be judged
satisfactorily during the flyover. If the S/N is adequate, the airplane
should continue the testing by executing additional normal takeoffs.
If the S/N is not adequate, the airplane should conduct the remainder
of the testing by flying horizontally over this or any other approved
microphone for the required number of tests. No delay would be
required for moving the microphone and setting up at a new station.
In principal, the noise levels at an alternate takeoff measuring
point could be corrected to approximate the levels at the 3. 5 nm ref-
erence distance. However, in practice the results for some applica-
tions would be less reliable than those derived from the horizontal
flight procedure. The reason is that airplanes generally are not
stabilized with respect to configuration, speed, and climb angle un-
til they have reached a height above airport of at least 400 ft and
that it is not considered safe to execute thrust cutback for noise
abatement below about 700 ft. Consequently, the use of an alternate
measuring point, located nearer to the climb path than the 3.5 nm
point, might result in noise levels that have been significantly in-
fluenced by the airplane climb performance below heights of 400 and
700 ft, contrary to the intent of the takeoff test procedure.
Another consideration is that as successful experience is acquired
5C-6
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with the use of the horizontal flight procedure, both as the only
procedure for propeller driven small airplanes and as an equivalent
takeoff procedure for all other airplanes, a decision might be made
to replace the currently specified takeoff and approach procedures
with horizontal flyovers. Such a decision would result in more con-
venience and less cost to the manufacturers and offer the potential
for the acquisition of a wide range of data suitable for community
noise impact studies.
It is recommended, therefore, that the noise measuring point for
takeoff be retained at 3.5 nm from the start of takeoff roll and that
the use of alternate measuring points, for the purpose of increasing
signal to noise ratios, not be permitted. A 1000 ft horizontal flyover
procedure should be required for all cases where the S/N is not ade-
quate. A correction formula should be developed which yields a level
in decibels which, when added to the noise level determined by means
of the 1000 ft horizontal flight procedure, approximates the noise
level at 3.5 nm from brake release. The correction formula should
be based upon both climb perfomance and speed.
In accordance with the above recommendation, the wording des-
cribing the takeoff measuring point in §C36.3(a) of FAR 36 is clear
and precise and changes are unnecessary. Details of the 1000 ft
horizontal flight procedure and the correction formula are included
under Section 5S, "Takeoff Test Conditions", of this Project Report.
5C-7
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(Q2) Approach
Experience as a result of FAA noise certification tests since 1969
has shown that the measuring point for approach (1 nautical mile from
threshold) is satisfactory for determining airplane noise levels that
result from stabilized approach operations conducted along a single
segment constant glide angle. However, if other approach procedures
such as a two-segment approach are standardized, then an additional
measuring point (or points) farther from the runway should be
specified for noise certification testing. The wording describing the
approach measuring point in §C36. 3(b) of FAR 36 is clear and precise
and changes are unnecessary until other than single segment stab-
ilized approaches are required.
(Q3) Sideline
Experience as a result of FAA noise certification tests since 1969
has shown that the sideline measuring point, on a line parallel to and
0.25nautical miles from the extended centerline of the runway, is
satisfactory for all airplanes regardless of number of engines.
Consequently, it is recommended that the alternative distance of 0. 35
hautical miles, applicable to airplanes powered by more than three
engines, be eliminated. The recommended wording for §C36. 3(c),
therefore, is as follows:
(c) For the sideline, at the point, on a line parallel to and 0. 25
nautical miles from the extended centerline of the runway,
where the noise level after liftoff is greatest.
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R. Noise Levels (§C36. 5 of FAR 36)
§C36. 5(a) of FAR 36 specifies that flight tests must show that the
noise levels of an airplane, measured at the measuring points des-
cribed in §C36. 3 of FAR 36, do not exceed the following values:
"(1) For approach and sideline, 108 EPNdB for maximum
weights of 600,000 Ibs. or more, less 2 EPNdB per
halving of the 600, 000 Ibs. maximum weight down to
102 EPNdB for maximum weights of 75, 000 Ibs. and
under."
(2) For takeoff, 108 EPNdB for maximum weights of
600, 000 Ibs. or more, less 5 EPNdB per halving of the
600, 000 Ib. maximum weight down to 93 EPNdB for
maximum weights of 75, 000 Ibs. or under. "
§C36. 5(b) of FAR 36 permits the noise levels specified above to
be exceeded (traded off) at one or two of the measuring points if:
"(1) The sum of the exceedance is not greater than 3 EPNdB;
(2) No exceedance is greater than 2'EPNdB; and
(3) The exceedances are completely offset by reduction at
other required measuring points. "
§C36. 5(c)of FAR 36 permits a greater exceedance for special prior
applications as follows:
"For applications made before December 1, 1969, for air-
planes powered by more than three turbojet engines with
bypass ratios of two or more, the value prescribed in (b)(l)
of this section may not exceed 5 EPNdB and the value pre-
scribed in paragraphs (b)(2)of this section may not exceed
3 EPNdB. "
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(Rl) Tradeoff and Prior Applications
The tradeoff provisions of §C36. 5(b) were justified in the preamble
of FAR 36 as follows:
"However, the trade-off feature is maintained since the
total noise exposure created by an airplane is related to
the noise transmitted to all three measuring points (side-
line, approach, and takeoff). It would, therefore, not be
rational to deny a type certificate to an aircraft that only
slightly exceeds the required noise levels at one or two
points if theexceedances can, in fact, be made up or offset
at the remaining measuring point(s), so that the net result
is an aircraft whose total noise exposure is no worse than
that of an aircraft that barely met the requirements at all
three measuring points. "
Experience as a result of FAA noise certification tests conducted since
1969 has shown no evidence that the above justification is not still
valid. The wording in §C36. 5(b), therefore, is clear and precise and
changes are unnecessary.
However, the provision that applications made before 1 December
1969 may have a greater exceedance is no longer needed. Therefore, it
is recommended that §C36. 5(c) be deleted.
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(R2) Compliance Noise Levels Proposed by FAA and ICAO
Experience as a result of FAA noise certification tests since 1969
has shown that current technology airplanes are capable of complying
with substantially lower noise levels than the requirements of
§C36. 5(a) listed above. The FAA has recognized this fact and pro-
posed lower compliance noise levels in Reference 28 (hereafter
designated FAA WP/39). Also, the ICAO Committee on Aircraft Noise
(ICAO CAN/4 ) in Reference 35 (hereafter designated ICAO WP/64)
has proposed lower compliance noise levels which, generally, are
less stringent than those of FAA WP/39.
Figures 2(a), (b), and (c) illustrate the compliance noise levels of
FAR 36 specified in §C36. 5 compared with the levels proposed in FAA
WP/39. The FAR 36 levels are designated 69 FAR 36 because they were
first effective in the year 1969 (and are effective to date). The FAA
WP/39 levels are dependent upon the number of engines required for
propelling the airplanes for sideline and takeoff, but are independent
of number of engines for approach. The FAA WP/39 levels represent
reductions from the 69 FAR 36 levels that are dependent upon airplane
weight and number of engines within the following ranges:
Sideline (5 to 9 dB),
Takeoff (1 to 10 dB), and
Approach (3 to 4 dB).
Figures 3(a), (b), and (c) illustrate the compliance noise levels of
69 FAR 36 compared with the ICAO WP/64 levels. The latter are in-
dependent of number of engines and agree with the FAA WP/39 levels in
only two cases (sideline four engines and approach). The ICAO WP/64
5C-11
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levels represent reductions from, the 69 FAR 36 levels that are depen-
dent upon airplane weight within the following ranges:
Sideline (5 to 6 dB),
Takeoff (2 to 4 dB), and
Approach (3 to 4 dB).
The formulae for the compliance noise level curves of all
three sets of requirements (69 FAR 36, FAA WP/39, and ICAO WP/64)
are listed in Table 2. It is interesting to note that the slopes of
the curves for 69 FAR 36 and ICAO WP/64 are identical for all three
measuring points. However, the slopes of the curves for FAA WP/39
agree with the other two sets of requirements only for sideline and
approach. The slope of the FAA WP/39 curve for takeoff is lower
(4 versus 5 dB per halving of weight) than that for 69 FAR 36 and
ICAO WP/64.
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(R3) Noise Levels of Existing Airplanes
Figures 4 (a) thru (g) show airplane noise levels, listed in Tables
3 (a) through (h), compared with the compliance noise level curves for
the three sets of requirements. The levels are plotted in terms of
number of engines relative to the sideline and takeoff measuring points
in order to facilitate comparisons with the requirements of FAA
WP/39. The data from Tables 3 (complied from the sources listed
in Ref 119) represent both certificated and estimated noise levels.
The data points shown in Figures 4 represent the noise levels of pre-
1969 technology airplanes as well as those for current technology air-
planes, the latter defined as those which can comply with 69 FAR 36.
The purpose of Figures 4 is to illustrate the wide range of noise
levels produced by the existing airplanes. The range for all of the
airplanes shown is over 40 decibels, varying from a low of about
78 EPNdB at takeoff to nearly 119EPNdB at approach. Many of the
data points are above the 69 FAR 36 curves but most are below.
Subsequent Figures will illustrate how the range for new aircraft can
be narrowed to levels substantially below 69 FAR 36 by application
of current and available technology.
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(R4) Current and Available Technology: Existing Airplanes
Figures 5 (a), (b), and (c) show the airplane noise levels listed in
Table 4 compared with the compliance noise level curves for 69 FAR
36. The 17 airplanes listed were chosen from Tables 3 on the basis
that they all meet the requirements of 69 FAR 36 by original design
and not with the use of retrofit hardware. Airplanes that can comply
with 69 FAR 36 are designated "current technology" airplanes and
those that cannot comply are designated "pre-1969 technology" air-
planes. The 17 current technology airplanes were selected, where
feasible, to include two models of each type; one at the low end and
one at the high end of their weight range. Hence, the sample of
current technology airplanes includes the influence of growth.
In order to be economically viable, most new aircraft (espe-
cially transport category) must have a certain and defined growth
potential. One reason for this is that the first models of airframe and
engine combinations may not be as efficient in terms of range, pay-
load, operating, costs, etc., as they can be after they have had the
opportunity to be tested and evaluated in service. Another reason is
that by the nature of the market, the first models are designed for
U.S. domestic operations for the anticipated level of traffic. Growth
versions are developed to satisfy the requirements of long-range in-
ternational operations. Generally, the most significant changes are
made in the engine in terms of increased thrust while maintaining an
adequate margin of safety. Increased thrust can be translated into
increased flight range with the same payload, increased payload for
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the same range, or some combination of both. Without growth
guaranteed by the manufacturers, most new aircraft types would have
such a limited market that, probably, they would not be developed.
The question has been asked that, from an environmental standpoint,
why should aircraft types be permitted to have new models (growth
versions) if those new models produce higher noise levels than the
original models? The answer is in two parts, one pertaining to econo-
mics and the other to environment.
The economics answer is based upon the fact that many, if not all,
airlines have need for aircraft which operate efficiently over various
ranges and with different payloads, and which allow for the desirable
growth in passenger and cargo traffic that is expected to occur with
time. Several models of a particular type would satisfy those requre-
ments while one model would not. One alternative for the airlines
would be to acquire additional types of aircraft (e.g., short, medium,
and long range). This alternative, however, would likely not be eco-
nomically reasonable because it would require more expensive main-
tenance and spare parts facilities to service several types of air-
craft, than would be required to service several models of a single
type of aircraft.
The environmental answer is based upon several considerations.
First, from a noise standpoint it makes little difference whether the
range and capacity requirements are met by a variety of types of air-
craft or by a variety of models of a given type. Second, if noise regu-
lations were to prohibit the noise of future models from exceeding the
5C-15
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levels of the initial model, the manufacturers probably would design
the initial models to comply with levels no lower than the maximum
permissible. This would be the only logical way of insuring that
noise regulations would not inhibit growth potential. The result, of
course, would be to produce greater noise than necessary from initial
models. Third, the airlines could operate only long range models of
a particular type of aircraft over all of their routes. This alternative
would not only be economically unreasonable but degrading to the en-
vironment as well. The result would be that the largest and noisiest
aircraft would be operating at many airports where smaller and less
noisy models would operate if they were available. Fourth, the airlines
could operate only short range models of a particular type over all of
their routes. Like the former, this alternative would be both econo-
mically unreasonable and degrading to the environment. Many of those
aircraft would be forced to refuel at some airports (hence produce noise)
which longer range models would overfly if they were available. Thus,
the number of exposures at a given airport would be greater than it
otherwise would be.
The 17 airplane sample does not include models of pre-1969 tech-
nology airplanes which can now comply with 69 FAR 36 by means of
retrofit applications of Quiet Nacelles (QN). The QN airplanes are not
current technology airplanes in the sense of original design, although
they can be and are being, in some cases, newly produced and may
continue to be for many years. Therefore, while the QN airplanes can
meet 69 FAR 36, they are not included in the 17 airplane sample
5C-16
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despite their potential for long term, existance.
Three curves are shown in Figures 5: the 69 FAR 36 requirements;
the least squares mean of the 17 airplane sample; and the mean less
three decibels. Note that the mean was determined over the range
of maximum aircraft weights from 10, 000 to 1,000,000 pounds. The
upper curves (69 FAR 36) are existing requirements and only pre-1969
technology airplanes cannot comply. In fact most current technology
airplanes can comply with substantially lower noise levels which
fact is indicated by the middle curves (mean). Consequently, if FAR
36 is to be amended for lower compliance noise levels representative
of current technology airplanes, the mean curves should be considered
as candidates along with those for FAA WP/39 and for ICAOWP/64.
The lower curves (mean -3 dB) represent a compromise choice of
compliance noise levels for available technology airplanes. It must be
understood that "available technology", as used here and defined pre-
viously, includes techniques and procedures which have been used ef-
fectively by some manufacturers for some applications. Consequently,
some set of curves through the lower range of the data scatter would
satisfy the above definition. The problem is to determine a rea-
sonable set of curves taking into consideration the fact that the various
types of airplanes do not all have the same purpose or mission. In
other words, available noise abatement technology which may be appro-
priate for one type of airplane may not be appropriate for another.
5C-17
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Mean
-1 dB
9
9
5
Mean
-2 dB
7
7
3
Mean
-3 dB
3
5
2
Mean
-4 dB
0
2
0
Mean
-5 dB
0
1
0
In arriving at the lower curves of Figures 5 as the compromise
choices for available technology, consideration was given to the num-
ber of airplanes of the seventeen that could comply with the mean,
the mean less one decibel, the mean less two decibels, etc. , tabulated
as follows:
Mean
Sideline 9
Takeoff 10
Approach 11
It is seen from the above listing that the majority of the 17 airplanes
could comply with the mean and only one with the mean less five dec-
ibels. The most reasonable set of curves for which some airplanes
could comply is the mean less three decibels which was chosen as the
compromise between the mean and the mean less five decibels, for
which only one airplane could comply.
Note that the airplane complying with the mean-5dB is the initial
model of the A300 B which has a relatively high thrust to weight (T/W)
ratio for a transport category airplane. In general, for a given weight,
the airplane with the largest T/W ratio would reach the greatest height
over the takeoff measuring point and have the greatest thrust reduc-
tion when power cutback is utilized. Both of these effects help reduce
noise levels at the takeoff measuring point. The A300 B illustrates
two important points. First, the initial version is substantially less
noisy than other airplanes in its weight class which probably would
not be the case if noise were not permitted to increase at a reasonable
5C-18
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rate with increase in maximum airplane weight. Second, a greater
than usual T/W ratio is an accessible technique for controlling air-
craft noise at takeoff and may not necessarily be wasteful of energy.
An important consideration that influenced the choice for the lower
curves (mean -3 dB) of Figures 5 was that the airplanes which could
comply should represent as much of the full weight range as possible.
For example, for takeoff one airplane can comply with the curves for
the mean less five decibels and two airplanes with the mean less four
decibels. However, both of these airplanes are in the moderately high
weight range and there is no representation in the lower weight range.
On the other hand, of the five airplanes which can comply with the
curves for mean less three decibels, two are in the low weight range
and three in the moderately high weight range. The fact that the
middle and highest weight ranges are not represented is unnecessary.
The lowest and moderately high weight ranges are adequately far apart
and the missions and purposes of the airplanes sufficiently disparate
to be indicative of the availability of the noise control technology for
the entire weight range.
It should be pointed out that ten airplanes can comply with the mean
-3dB curves on an individual measuring point basis. That does not
mean that ten of the seventeen control group airplanes can comply
with the mean-3dB curves collectively. Nevertheless, the data of
Figures 5 show that six airplanes have noise levels less than the
mean at all three measuring points, and two more airplanes can
comply with the aid of the 3/2 dB tradeoff provision. Therefore, it
5C-19
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is not unreasonable to assume that technology is available to "fine
tune" the noise control of these existing airplanes for a maximum of
three decibels more noise reduction, at each of the three noise mea-
suring points, by the use of such techniques as sound absorption ma-
terial (SAM\. thrust cutback, increased thrust/weight ratios, improved
lift/drag ratios, reduced approach flaps, etc. Consequently, with
available noise control technology capability, new type design airplanes,
that is airplanes that are not constrained to existing airframes or en-
gines, should be able to comply with noise levels at least three decibels
lower than existing airplanes such as the Cessna, Learjet, Falcon,
Airbus, Corvette, DC-10, L-1011, and B-747.
The formulas for the mean curves of the 17 airplane sample, for
the range of maximum weights from 10, 000 to 1, 000, 000 pounds, and
the reduction in noise levels from the 69 FAR 36 levels are as follows:
Formulas Reduction, dB
Sideline: EPNL = 7 Log (W) + 59: 7 to 15 (8a)
Takeoff: EPNL = 12 Log (W) + 32: 3 to 13 (8b)
Approach: EPNL = 7 Log (W) + 63: 3 to 11 (8c)
The constants of the above formulas have been rounded off so that the
equations will yield levels within a fraction of a decibel of the exact
mean.
An additional discussion on the mean concept for the development
of compliance noise levels representing current and available noise
control technology is given in Reference 120.
5C-20
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(R5) Comparisons of Proposed Compliance Noise Levels
Figures 6 (a), (b), and (c) compare the mean curves of the 17
airplane sample with the curves of FAA WP/39. It is apparent that the
mean curves are more stringent (have lower levels) than those of FAA
WP/39, except for the following:
Sideline. The mean curve has levels slightly higher (one
decibel or less) than the 3 engine curve for aircraft
weights above about 200, 000 pounds and the 2 engine
curve for aircraft weights above about 75, 000 pounds.
Takeoff. The mean curve has levels up to four decibels
higher than the 2 engine curve for aircraft weights
above about 40, 000 pounds and up to one decibel higher
than the three engine curve for aircraft weights above
about 75, 000 pounds.
Figures 7 (a), (b), and (c) compare the mean curves of the 17
airplane sample with the curves of ICAO WP/64. Coinciding curves
of FAA WP/39 are also shown for reference. It is seen that the mean
curves have lower levels than ICAO WP/64 in all cases except for
takeoff at a range of weights from about 75, 000 to 150, 000 pounds
where the mean curve is up to one decibel greater.
Three sets of curves have been considered as candidates for com-
pliance noise levels, namely, FAA WP/39, ICAO WP/64, and the mean
of the 17 airplane sample. Each of these candidates has merit. Sup-
port for FAA WP/39 and ICAO WP/64 are given in References 28 and
35, respectively, and support for the mean has been presented in the
5C-21
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previous discussion and in Reference 120. For the most part, the
mean curves are the most stringent of the three.
In some cases, however, the levels of the mean are less stringent
than those of FAA WP/39 and ICAO WP/64. Consideration should be
given, therefore, to the concept of proposing compliance noise levels
which would be the most stringent combination of the three candidate
sets of curves. The results of the most stringent combination of noise
levels represented by the curves for FAA WP/39, the curves for the
mean of the 17 airplane sample and the mean -3dB are shown in
v
Figures 8 (a), (b), and (c) and Figures 9 (a), (b), and (c). The curves
representing ICAO WP/64 were disregarded on the basis that, except
for a very small portion of the airplane weight range, they were less
stringent and the exception was not significant.
Consequently there is one set of curves representing pre 1969 tech-
nology (69 FAR 36); four candidates sets of curves representing cur-
rent technology (ICAO WP 64, FAA WP/39, mean, and modified mean);
and two candidate sets of curves representing available technology
(mean -3dB and modified mean -3dB). The applicability is recom-
mended as follows:
1. Newly produced airplanes of older type designs, which are
69 FAR 36 requirements in accordance with Reference 13.
2. New type designs applied for on or after 1 January 1975, which
are current technology requirements.
3. Airplanes with "major acoustical changes" to older type de-
signs which are newly produced on or after 1 January 1975,
which are current technology requirements.
5C-22
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4. New type designs applied for on or after 1 January 1980, which
are available technology requirements.
The choice of the mean levels for current technology requirements
would have in its favor, simplicity and the fact that the levels represent
known and demonstrated noise control technology. In other words,
the state of the art includes efficient, high performance airplanes such
as the B-747, L-1011, DC-10, Corvette, Airbus, Falcon, Learjet,
and Cessna, all of which can comply with the mean levels.
However, any one of the four candidate sets of curves for current
technology has merit in the sense that the compliance noise levels for
new type design airplanes would be significantly lowered from those of
69 FAR 36. There is not a great deal of difference in stringency be-
tween any of the candidates except for the lower weight range which
corresponds mainly to general aviation aircraft. Therefore, any one
of the four candidates would be acceptable provided they are applicable
only to current technology airplanes. In other words, any one of the
four sets of curves (or a compromise among them) would not be un-
reasonable choices for immediate implementation considering that the
available technology requirements would follow after the lapse of
several years. Furthermore, the current technology levels would be
applicable to major acoustical changes of older type designs.
Major acoustical changes to older type design airplanes would in-
clude new type engines or radically modified existing type engines such
as the JT8D "Refan" included on newly produced existing type air-
planes. However, a major acoustical change would not include
5C-23
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modifications to existing type airplanes such as "Quiet Nacelles", up-
rated or growth versions of original equipment engines, and existing
type engines different from the original equipment engines.
In regard to available noise control technology, the modified mean
-3dB set of curves are more stringent than the mean -3dB set only
for two engine takeoff where they are one decibel or less more strin-
gent over part of the weight range. Considering the convenience of the
single line to outweigh any possible benefits due to one decibel or less
stringency, it is recommended that the compliance noise levels for
available technology be represented by the mean -3dB curves. The
formulas and reductions in noise levels from the 69 FAR 36 levels, for
the range of maximum weights from 10, 000 to 1, 000, 000 pounds, are
as follows:
Formulas Reduction, dB
Sideline: EPNL = 7 Log(W) +56: 10 to 18 9(a)
Takeoff: EPNL = 12 Log(W) +29: 6 to 16 9(b)
Approach: EPNL = 7 Log(W) +60: 6 to 14 9(c)
5C-24
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(R6) Alternate Schemes for Current Technology
Two sets of noise levels, represented by the curves shown in
Figures 5, have been proposed as modifications to 69 FAR 36. The
development of these proposed noise level modifications was based
upon a scheme where a control group of seventeen 2, 3, and 4 turbojet
engine airplanes, all of which can comply with 69 FAR 36, were chosen
as typical examples of the application of current noise abatement
technology.
A least squares mean set of curves was derived for the 17 airplane
sample and denoted as candidates, along with the curves for FAA WP/
39 and ICAO WP/64, for compliance noise levels representing current
noise control technology. Further analysis indicated that the mean
-3dB set of curves would be suitable choices for compliance noise
levels representing available noise control technology. Comparison
of the curves for the mean, FAA WP/39, and ICAO WP/64 show that,
for the most part, the mean curve is the most stringent of the three.
Minor exceptions occur for takeoff, for part of the weight range and
only for 2 and 3 engines.
Alternate schemes to the above for modifying the compliance noise
levels of 69 FAR 36 have been proposed in addition to the specific
recommendations of FAA WP/39 and ICAO WP/64. Other schemes or
philosophies, are discussed in References 121 thru 125. A general
concept that is emphasized in those references is that noise is more
closely related to thrust and thrust/weight ratio than to weight for
turbojet propelled airplanes. In particular, some contend that, for
5C-25
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takeoff, maximum climb thrust (as opposed to maximum takeoff
thrust) is the more important variable.
In addition, the point is made that various airplane design require-
ments (such as safety regulations pertaining to engine performance
during climb, wing loading, lift/drag ratios, and range/ payload)
which affect the choices of size of engine, number of engines,
and thrust/weight ratio, are more influential parameters governing
aircraft noise than maximum aircraft weight. Consequently, it is
claimed (e.g., References 122 and 125) that a scheme which relates
compliance noise levels for turbojet airplanes to maximum weight
only is an over-simplification which may be more stringent for some
airplanes than for others.
There is no doubt that aircraft are very complex sound sources and
that many interrelated parameters strongly influence the generation
and radiation of noise. The control of aircraft noise, therefore, is
most effective when planned in the design stage and when as many as
possible of those influential parameters are identified and controlled.
However, it is not reasonable, nor expected, that noise standards
should be equivalent to design procedures. The noise standards
should be as simple as possible without inequities. Each aircraft/
engine manufacturer has his own design procedures suited to his equip-
ment, professional skills, and aircraft mission. One set of aircraft
noise standards could not possibly satisfy the design requirements
of all manufacturers and aircraft missions.
Furthermore, since aircraft noise is a very important public is-
sue, attempts should be made, to the maximum extent reasonable, to
5C-26
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base the standards upon easily understood and readily obtainable
parameters. The public has a right to be informed on this issue with
a minimum of confusion. This is not to say that the standards should
be compromised in order to inform the public but, on the contrary,
the standards should not be complicated in order to provide a design
service to the manufacturer which at the same time might be confusing
to the public.
In view of the preceding discussion, effort was devoted to analyzing
the available noise data in terms of maximum thrust, thrust/weight
ratio, and number of engines. The purpose was to determine whether
those parameters would lead to significantly better correlations with
noise than does maximum aircraft weight. The intent was that if the
correlation would be substantially better with those parameters, then
perhaps, more fundamental design characteristics (climb thrust, lift/
drag, wing loading, etc. ) should be evaluated as well.
The analysis began with the 17 airplane sample representing typ-
ical examples of 2, 3, and 4 engine airplanes which can comply with
69 FAR 36. These airplanes, to various degrees, have applications of
current noise control technology. Furthermore, these airplanes are
relatively new, competitive, and can be operated at a profit. There
is no reason why new type design airplanes (or major acoustical
changes to older type designs) should be permitted to produce greater
noise.
Figure 10(a) shows the relationship between maximum airplane
thrust and maximum airplane weight for the 17 airplane sample. The
equation of the least squares mean through the data points is given by:
5C-27
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Log (T) = 0. 923 Log (W) - 0. 107 (10)
where T and W are given in pounds.
It is seen that the correlation between maximum thrust and maximum
weight is excellent, indicating that if noise correlates well with thrust,
it would, for all practical purposes, correlate equally well with weight.
Figure 10(b) shows the relationship between the thrust/weight ratio
(maximum value in each case) and maximum aircraft weight for the 17
airplane sample. The equation of the least squares mean is given by:
Log (T/W) =-0.077 Log (W) - 0.107 (11)
The correlation is good but not as good as for thrust versus weight.
It is seen that there is a modest trend for thrust/weight ratio to de-
crease with increasing weight. However, it cannot be concluded that
lighter airplanes always have greater thrust/weight ratios than heav-
ier airplanes. Nor can it be concluded that thrust/weight ratios always
decrease with increasing number of engines.
Figures 11 (a), (b), and (c) show the relationship between noise
level and maximum aircraft thrust for the 17 airplane sample. The
equations of the least square mean are given by:
Sideline: EPNL = 7 Log (T) + 63 (12a)
Takeoff: EPNL = 13 Log (T) + 33 (12b)
Approach: EPNL = 7 Log (T) + 67 (12c)
The constants of the above formulas have been rounded off so that the
equation will yield levels within a fraction of a decibel of the exact
mean. It is seen by comparing Figures 5 and 11 that the correlation
between noise and maximum thrust is no better than between noise
and maximum weight.
5C-28
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The slopes of the relationship between noise and thrust are given by:
Sideline: 2. 107 dB per double thrust
Takeoff: 3.913 dB per double thrust
Approach: 2. 107 dB per double thrust
The values for the slopes compare favorably with the views expressed
by others (e.g., References 122 and 125) that noise increases about
three decibels for each doubling of thrust.
Figure 12 (a1* shows the relationship between noise levels normal-
ized for weight and the number of engines. The normalization was
performed in conformance with Equations (8a), (8b), and (8c) which
are the formulas for the mean curves in terms of weight. It is seen
from Figure 12(a) that some 3 and 4 engine airplanes have lower
normalized levels than some 2 engine airplanes. Also, some 4 engine
airplanes have lower normalized levels than some 3 engine airplanes.
It can be concluded, therefore, from analysis of the 17 airplane sample
that there is no indication that the stringency of compliance noise levels
should increase for decreasing number of engines. That is, 2 engine
airplanes should not be required to meet lower noise levels than 3
engine airplanes, etc.
Figure 12 (b) shows, in a similar manner, the relationship be-
tween noise levels normalized for thrust and the number of engines.
The normalization was performed in conformance with Equations (12a),
(12b), and (12c) which are the formulas for the mean curves in terms
of thrust. The same observations can be made from Figure 12(b)
that were made from Figure 12(a). That is, there is no indication
that the stringency of compliance noise levels should increase for de-
creasing number of engines. Furthermore, the correlation of number
5C-29
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of engines with respect to noise is about the same whether normalized
with respect to thrust or to weight.
Figure 13 shows the relationship between thrust/weight ratio and
number of engines for the 17 airplane sample. This is simply another
way of illustrating the conclusions reached from Figure 10(b). That
is, although there is a trend for thrust/weight ratio to decrease with
increasing number of engines, it cannot be concluded that airplanes
with fewer engines always have higher thrust/weight ratios.
The foregoing analysis examined the 17 airplane control sample
for evidence that noise could be correlated better with more basic
air plane/engine parameters than weight. Thrust, thrust/weight ratio,
and number of engines were considered and the correlation was no
better than for weight alone. It must be understood that maximum
thrust and maximum weight were used in the analysis, and the possi-
bility exists that the correlation might be better if the actual thrusts
and weights for each operational mode were considered. For example,
if actual thrust for sideline (based upon thrust lapse rate), climb thrust
for takeoff, and landing thrust and weight for approach were used
instead of the maximum values, the correlation with noise might have
beenbetter.
However, more basic parameters than maximum aircraft weight
are performance data which are not readily available and, in some
cases, might be proprietary. The extra effort needed to acquire that
data does not appear to be warranted because if significantly better
correlation would result, some evidence of that trend should have been
indicated by the maximum values. Any such trend, if it exists, is
not very strong.
5C-30
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(R7) Future Technology
The substantial achievements in noise reduction, such as mani-
fested by the mean curves, has encouraged predictions that aircraft
noise at the FAR 36 measuring points can be reduced ten decibels
or more (e.g., the CARD Study, Reference 126). These achievements
came as a result of research, development, and demonstration (RD&D)
initiated before the promulgation of 69 FAR 36. Noise control RD&D,
funded both by Government and industry, are continuing and their re-
sults should be included in the designs of new aircraft types some
time in the future, probably beyond 1985.
The National Aeronautics and Space Administration is the single
largest contributor to RD&D on aircraft noise control. A compre-
hensive report on the NASA noise reduction technology programs and
plans, as of March 1973, is given in Reference 127. Although that
report has not been revised in the past three years, the material is
pertinent and the NASA programs and plans discussed therein should
have a strong influence on future aircraft design. Reference 128, pub-
lished subsequent to the NASA report, provides a brief summary of
the large amount of information available on air transport noise
control and future needs and research trends. Reference 129 contains
a status report on propulsion noise RD&D conducted by NASA. These
later references, therefore, serve a function of partially updating the
earlier NASA report.
The noise reduction accomplishments to date and the extensive
programs in progress do indeed hold promise for further substantial
5C-31
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gains. Nevertheless, there has to be a limit, or floor, beyond which
it is technologically impractical, or even impossible to proceed. The
following three sources of noise have been identified as potential noise
floors which may be relatively near at hand: jet exhaust stream,
engine core, and flow surface interactions (References 5, 121, 125,
127 through 131).
Noise from the jet engine exhaust stream mainly results from the
mixing of the high velocity gas discharge with the ambient air. The
noise sources are usually defined as acoustical quadrupoles whose
overall strength is proportional to the relative jet stream velocity
to the eighth power. The absolute noise level for any given velocity
is dependent upon various factors such as exhaust nozzle size and shape
and various influences upstream of the nozzle such as geometry,
roughness, turbulence scale, etc. Current methods of jet noise
reduction involve the use of exhaust noise suppressors which break
up the main jet and, in effect, change the manner in which it mixes
with the ambient air. Such suppressors have been most effective at
the higher jet velocities, where the noise is greatest, but are accom-
panied with significant penalties in thrust, drag, fuel consumption,
and airplane empty weight.
The most effective procedure to control jet stream noise without
excessive penalties is to reduce the jet velocity but maintain thrust by
increasing the mass flow. The technique used for turbofan engines is
to increase the bypass ratio. Incidentally, high bypass ratio turbofan
engines which are efficient for subsonic airplanes were not developed
originally, nor specifically, for noise control but rather to improve
5C-32
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fuel economy. The noise levels at the lower jet exhaust velocities
are higher than would be expected based on jet mixing noise only.
There is evidence that other sources of noise are important in this
velocity range. For example, sources generated inside the engine,
commonly referred to as core engine noise, may dominate.
Core engine noise is defined (Reference 5) as the noise produced by
the gas generator portion of the gas turbine engine, either solely, or
as influenced or amplified by the fan discharge, tail pipe, and any
other portion of the exhaust system. Core engine noise is assumed to
radiate only in the aft quadrant of the engine, and its sources are
generated upstream of the tail pipe exit plane. Core engine noise does
not include compressor-generated noise radiating from the engine in-
let nor fan-generated noise radiating from either the engine inlet or
exhaust ducts. It may, however, include compressor-generated noise
transmitted downstream through the engine flow passages or fan-gen-
erated noise enhanced by interaction with the core engine noise or with
the gas stream.
Flow surface interaction noise is produced by the interaction of
flows with solid surfaces of the aircraft, and can result from propul-
sive and nonpropulsive sources. An example of a propulsive source
is a powered-lift aircraft where the interaction of the jet engine ex-
haust with the wing and flap surfaces can be significant noise sources.
Nonpropulsive noise is produced by aerodynamic boundary layers or
the turbulence produced by air passing over and around the airframe
and its various components, such as flaps, landing gear, landing gear
5C-33
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cavities and doors, and other protuberances or cavities that tend to
disrupt smooth flow.
It is becoming more apparent that nonpropulsive noise (also re-
ferred to as airframe, aerodynamic, or selfnoise) must be considered
in the design of future aircraft if significant further noise reduction is
to result. Airframe noise is that which would be radiated by an air-
craft in flight with the engines inoperative. Of the three FAR 36
measuring points, it would be most noticeable at approach because
engine power and distance to the microphone are least. There is
evidence that aircraft noise is approaching the level which would limit
the feasibility of further engine noise control. There would be no
point in new and expensive engine noise control programs if airframe
noise is the limiting factor.
Figure 14 shows the estimated range of nonpropulsive noise at the
approach measuring point for typical airplanes. The range is con-
structed from the ranges given in References 128 and 130. It is
interesting to note that the upper limit of the range is less than one
decibel below the mean-3dB compliance noise level curve and has
the same slope. Reference 131(a) reports the results of an analysis of
about ten commercial and military airplanes which substantiates the
validity of that range of levels, including the slope. The conclusion of
Reference 131(a) is that the trend of the data is a line which has a
slightly greater slope than the 69 FAR 36 minus 10 dB curve. Such a
line would lie within the range shown whose limits have a slope equal
to 2. 107 dB per doubling of weight which is slightly greater than the
5C-34
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2. 000 dB per doubling of weight of the 69 FAR 36 curve for approach.
It is apparent from Figure 14 that the compliance noise levels for
approach, defined by the mean-3dB curve, have nearly reached the
upper boundary of the airframe noise floor. Further reductions in
the compliance noise levels for approach are contingent upon the de-
velopment of technology for reducing the nonpropulsive noise sources.
Note that the range of Figure 14 pertains to typical airplanes which
contain a substantial number of protuberances or cavities that tend
to disrupt smooth flow and generate noise. A reasonably clean air-
plane would be expected to have an airframe noise floor lower than
the upper boundary shown. The development of compliance noise levels
representative of future noise control technology, would, therefore,
be dependent upon the ability to identify and predict the lower limits
of airframe noise for all three measuring points.
Figures 15 (a), (b), and (c) show predictions for nonpropulsive
noise floors of aero dynamic ally clean airplanes. The predictions were
derived from data presented in Reference 131(b) based upon calculated
noise spectra radiating from aero dynamic ally clean wings sized for
600, 000 Ib airplanes. Of course, no real airplane can ever be equiv-
alent to a clean wing and the predictions shown simply represent ideal
minimum levels. The slopes of the curves for the ideal noise floors
are assumed to be the same as shown in Figure 14, that is, the same
as the slope of the mean-3dB approach curve. Also, the distance from
the clean airplane to the microphone was assumed constant for the full
weight range which is reasonable for the sideline and approach meas-
5C-35
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uring points. The assumption of a constant height of 1000 feet for the
takeoff measuring point is reasonable for the 600, 000 Ib airplane but
probably not for lighter weight airplanes. The height of an airplane
above the microphone is dependent upon airplane climbout performance
which, generally, is inversely related to airplane weight. Thus, a
10,000 Ib airplane would be expected to have a greater height at 3.5
nautical miles from brake release than a 600, 000 Ib airplane.
The development of compliance noise levels representing future
noise control technology is dependent upon determining the limiting
levels resulting from the three likely floor sources (jet exhaust stream,
engine core, or airframe). It appears at this time that airframe noise
is the limiting source in the sense that there is no demonstrated tech-
nology which will permit noise levels lower than the self noise genera-
ted by a reasonably clean airframe. Although it is possible that the
levels of jet stream or core engine noise may bottom out before air-
frame noise, the technological capability for substantially lowering
the levels of the jet and core sources appears to be more promising
than for the airframe source. Consequently, the following development
of future noise control technology curves will pertain to estimated
limits for airframe noise.
In the development of the noise predictions for the aerodynamically
clean wing included in Reference 131(b), about five decibels was esti-
mated to account for the noise effects of the normal cavities and pro-
tuberances (Haps, landing gear, etc.) during approach operations. For
sideline and takeoff operations, the difference in noise levels between
5C-36
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clean and dirty configurations would be expected to be about the same
or slightly greater than for approach. The reason is that airframe
noise is a function of airspeed and the magnitude of the protuberances;
the speed being greater for sideline and takeoff operations than for
approach and the effect of protuberances being slightly less. The
above statement is based upon the assumption that takeoff flaps and
landing gear would be fully deployed when the noise is measured at
the sideline and takeoff measuring points. Rapid cleanup (gear and
flap retraction as soon as feasible) would reduce the level of the es-
timated airframe noise at the sideline and takeoff measuring points.
If rapid cleanup is eventually included as part of the FAR 36 flight
test procedures, the above assumptions may need to be revised.
The specific incremental levels chosen for representing the differ-
ences between a clean wing and a reasonably clean airframe cannot be
established with absolute certainty at this time. Nevertheless, the
values chosen are logical choices based upon available data and are
adjusted to yield round numbers at the maximum aircraft weight
limits. The assumed incremental levels are:
(a) Sideline, 7.5 dB;
(b) Takeoff, 7.5 dBj
(c) Approach, 5.5 dB.
The increment for approach is approximately five decibels in accor-
dance with the recommendation of Reference 131 (b). The increments
for sideline and takeoff have been assumed to be equivalent because
the airplane speeds and configuration should be about the same. A
5C-37
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two decibel difference between the increments for sideline and takeoff
and for approach appears reasonable considering the differences in
speed and configuration.
Figures 16 (a), (b), and (c) show the proposed compliance noise
level curves representing available and future noise control technol-
ogy derived from the mean -3dB of the 17 airplane sample and the
foregoing analysis for future technology. The two curves are further
identified as 80 FAR 36 and 85 FAR 36 to indicate representative time
periods for implementation.
The future technology curves for sideline and approach require
little explanation; they are the curves of Figures 15 (a) and (c) with
the levels adjusted linearly upwards by 7. 5 and 5. 5 decibels, respec-
tively. The curve of 85 FAR 36 for takeoff requires a more detailed
explanation because the modifications to Figure 15(b) include a slope
adjustment as well as a linear level adjustment.
The slope of the noise floor curve shown in Figure 15 (b) results
from the assumption that the airplane has a constant 1000 feet height
above the takeoff measuring point. As discussed previously, this
assumption is not realistic because a 10, 000 pound airplane would be
expected to be substantially higher than a 600, 000 pound airplane at
3. 5 nautical miles from brake release. Probably, the lighter airplane
would be two to four times as high as the larger airplane depending
upon climbout performance. Since the estimated levels of airframe
noise are tenuous, especially for levels applicable to airplanes about
ten years in the future, the slope of the 85 FAR 36 curve for takeoff
was chosen for convenience to be the same as for the 80 FAR 36
5C-38
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curve. This assumption resulted in a slope adjustment equivalent
to nine decibels difference between the 10, 000 and 600, 000 pound air-
planes. A noise level difference of nine decibels would result from
a height ratio of about 2. 82, assuming an inverse square relationship.
Therefore, if the height of a 600, 000 pound airplane is assumed to
be 1000 feet, the 10, 000 pound airplane would be at a height of 2820
feet. This is a reasonable assumption and greater refinement
probably is unnecessary.
It must be emphasized that the future technology noise compliance
curves shown in Figures 16 represent airframe noise floors predicted
at this time. The predictions are, admittedly, rough and it is con-
ceivable that the results of RD&D within the next ten years could lead
to even lower noise levels. For example, it was assumed, based upon
rather simple predictions, that the ultimate lower limit would be the
noise levels produced by an aerodynamically clean wing. In addition,
a further assumption was made that noise levels of practical air-
frames could approach those of clean wings by only 7. 5 dB for sideline
and takeoff and 5. 5 for approach. Therefore, RD&D should be con-
ducted with objectives which include the determination of airframe
noise levels for clean airframes and the development of design data
for practical airframes which would narrow the airframe noise gap
between clean and practically clean airframes.
5C-39
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(R8) Compliance Curves Compared with CARD Study Goals
The 1970-1971 Civil Aviation Research and Development (CARD)
Policy Study (Reference 126) conducted "...a comprehensive review
of policies affecting civil aviation, of the problems confronting it, and
of the potential it possesses for future contributions to the Nation."
The CARD Study determined that there are a number of serious aviation
related problems that are rapidly growing more severe, including the
impact of civil aviation on the environment. The impact, according
to the CARD Study, was evident in the public concern regarding noise,
air pollution, water pollution, esthetics, ecological disturbances, and
meterological changes. Of these effects, the CARD Study judged noise
to be most important and a critical constraint to the future growth
of civil aviation.
The CARD Study recommended that "Research goals should be es-
tablished on the basis of the desired end result; that is, the achieve-
ment of noise levels permitting the introduction of new systems
compatible with future environmental goals. This will require the ac-
ceptance of these systems by local communities so airports can be
located, and suitable operations conducted, where they will satisfy the
transportation needs in an optimum way. " The objectives for meeting
these goals, according to the CARD Study, ". . . should be aircraft
operations in which the observed noise levels, at or beyond the airport
boundaries, are compatible with ambient or background levels for
specified land use. "
The specific noise level research goal recommendations of the
CARD Study for 1981 are shown in Figure 17 (a) compared with the
5C-40
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levels for 69 FAR 36. The top line of the CARD Study recommenda-
tions pertains to compliance noise levels at the FAR 36 measuring
points for sideline, takeoff, and approach. No distinction is made,
however, between the levels at each of the three measuring points.
The bottom line of the recommendations represent the maximum
noise levels of aircraft perceived at airport boundaries when operating
in accordance with optimum approach and climbout procedures. Thus,
v the two lines represent a range or envelope of levels that should not
be exceeded by new aircraft by 1981. However, the full width of the
range is not necessarily relevant to type certification of aircraft as
represented by FAR 36 or modifications thereto. For comparison
purposes, the 69 FAR 36 levels are shown as a range also. It is seen
that the CARD Study recommendations are that, by 1981, noise from
all new airplanes should be reduced at least 10 decibels below 69 FAR
36 and possibly as much as 22 decibels, depending upon the measuring
point and the airplane weight.
The CARD Study research goal recommendations for 1981 are
shown compared with the range of mean levels of the 17 airplane sam-
ple in Figure 17(b). The range of levels for each case, as explained
previously, is the envelope of levels pertaining to the three measuring
points except for the lower limits of the CARD Study range which rep-
resent noise levels at airport boundaries. It is seen that part of the
range of the mean includes part of the range of the CARD Study.
Specifically, the upper limits of the CARD Study are bettered by as
much as 3 decibels for aircraft weights below 18, 000 pounds. Com-
paring the two ranges, the CARD Study recommendations are that,
5C-41
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by 1981, the noise from all new airplanes should be reduced by a
minimum of about 0 to 8 decibels below the mean and possibly as
much as about 18 decibels, depending upon the measuring point and
the airplane weight.
The CARD Study research goal recommendations for 1981 are
shown in Figure 17 (c) compared with the range of levels for 80 FAR
36. It is seen that part of the range of 80 FAR 36 is below the CARD
Study range. Specifically, the upper limits of 80 FAR 36 would better
the CARD Study recommendations by as much as 6 decibels for aircraft
weights below 32,000 pounds. Comparing the two ranges, the CARD
Study recommendations are that, by 1981, the noise from all new
airplanes should be reduced by a minimum of about 0 to 5 decibels
below 80 FAR 36 and possibly as much as about 15 decibels, depending
upon the measuring point and the airplane weight. It is apparent,
therefore, that implementation of available noise control technology
(represented by 80 FAR 36) would very nearly meet the minimum goals
recommended by the CARD Study.
Figure 17 (d) compares the ranges of 85 FAR 36 and the CARD
Study research goal recommendations for 1981. It is seen that the
CARD Study upper limits are bettered for all aircraft weights except
for less than one decibel at about 75, 000 pounds. Furthermore, the
CARD Study lower limits are bettered by as much as 7 decibels for
aircraft weights below about 40, 000 pounds. In summary, the CARD
Study goals can nearly be achieved by the 80 FAR 36 levels and can
be achieved fully by the 85 FAR 36 levels.
5C-42
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(R9) Predicted Noise Levels for Major Acoustical Change Airplanes.
As defined in FAR Part 21, changes in type design are classified
as minor and major. A "minor change" is one that has no appreciable
effect on the weight, balance, structural strength, reliability, opera-
tional characteristics, or other characteristics affecting the airworthi-
ness of the aircraft. All other changes are "major changes" which
may include an "acoustical change" which is a change in the type design
which may increase the noise levels created by the airplane. However,
as used here, a major acoustical change in older type design airplanes
is a special kind of acoustical change which consists of the application
of current noise control technology equipment to older type design air-
planes. It would not include, however, modifications such as "Quiet
Nacelles", updated or growth versions of original equipment engines,
and existing type engines different from original equipment engines.
It is important that a distinction be made between changes in type
designs that are a result of normal growth of older technology equip-
ment and those that are a result of the application of current technology
equipment. It is reasonable to expect that the latter should include
the noise reduction benefits inherent in the current technology, par-
ticularly if the current technology was funded and developed for the
purpose of noise control (e.g., NASA Refan). In this regard, growth
versions of the original JT8D-109 refan engine (specifically engine
models JT8D-209 or JT8D-217) should not be permitted to make more
noise than the initial JT8D-109 engine developed by NASA.
Figures 18 (a), (b), and (c) show the predicted noise levels for
the potential major acoustical change airplanes listed in Table 5 com-
5C-43
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pared with the mean curve of the 17 airplane sample representing
current technology. The levels of these eleven airplanes are given
in References 132.
By comparison of the sideline noise levels of the eleven airplanes
with the levels represented by the mean curve, it is seen that all
but three of the airplanes (Nos. 4, 10, and 11} comply. For takeoff,
only No. 10 cannot comply and for approach, all but four (Nos. 1,
3, 10, and 11) comply. However, of the eleven airplanes, only two
(Nos. 10 and 11) exceed the mean curve by more than two decibels,
while the remaining three (Nos. 1, 3, and 4) can comply by exercising
the 3/2 decibels tradeoff provision. Therefore only two (Nos. 10
and 11) of the eleven proposed airplanes that would correspond to the
major acoustical change classification have predicted noise levels that
could not meet the mean levels of the current airplane types.
The results shown in Figure 18, which indicate that airplane No. 10
(B-727-300B) would not be able to comply with the mean curve could
have significant environmental implications according to the manu-
facturer (Boeing). If, for example, a new rule pertaining to major
acoustical change airplanes was too stringent for the B-727-300B,
that airplane would not be produced. Instead, newly produced air-
planes of older type designs, which would be required to comply only
with the 69 FAR 36 curve, might be produced as alternatives. The
alternative airplanes, according to Boeing, would have a greater ne-
gative impact on the community noise environment although the noise
levels at the FAR 36 measuring points would be approximately the
same.
*
5C-44
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It should be recognized that, while Boeing has a vested interest in
marketing the B-727-300B, their point may be valid. Therefore, the
following statement, quoted from Reference 132(e\ is included to in-
sure that the manufacturer's position is presented correctly and com-
pletely.
"The 727-300B is in the final design stages and will incor-
porate the noise reduction advantages of the NASA refan
program. The design makes use of the technology de-
veloped on the refan program, but within the practical
constraints of adopting a modified engine to an existing
design. Limitations on the refan installation include num-
erous configuration as well as performance and economic
considerations, all of which must be traded to arrive at
a practical airplane design incorporating community noise
reduction.
Based on full scale ground static JT8D-109 and -115 test
data, and a comprehensive 727 - JT8D flight data base,
community noise reductions relative to today's operational
727-200 of nominally 4 to 6 at high power and 6 to 8 on
landing are expected. These anticipated operational noise
reductions have been obtained in conjunction with an in-
crease in airplane capacity that is probably adequate to
result in a saleable product.
Technology advances planned to be incorporated into the
-300B installation include advanced inlet lining, a low
noise rotor / stator system, engine / rotor / stator lining,
maximum fan case lining, nacelle fan/turbine/core lining,
a jet exhaust noise mixer and a core noise plug suppressor.
In addition, aerodynamic changes have been made that im-
prove noise - performance including a wing tip extension
and leading edge high lift devices. Comparing noise levels
of current operational 727-200 airplanes with the -300B
shows a reduction in noise under the flight path on takeoff
and approach, reduced sideline noise, and reduced foot-
print area at all noise levels. The airplane will comply
with FAR-36 and has the longer term potential of com-
pliance with reduced FAR-36 requirements. These ad-
vances are the result of the NASA refan technology dev-
elopment program, as well as agressive noise reduction
efforts at The Boeing Company and at Pratt & Whitney
Aircraft. "
However, in opposition to Boeing's position, it must be emphasized
5C-45
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that of the eleven airplanes shown in Figure 18, only the B-727-300B
and the BAC-111-700 cannot comply. Therefore, it is not a foregone
conclusion that alternative airplanes must be those which can comply
only with the 69 FAR 36 curve. It is reasonable to assume that com-
petition will insure the development of major acoustical change air-
planes which can comply with any one of the four candidate sets Of
requirements for current technology airplanes.
Note, at this date, the 727-300 B program is no longer active and
the foregoing discussion concerning that airplane is academic. Never-
theless, the 727-300 B illustrates the concept of a major acoustical
change and the need for establishing requirements to insure that new
airplanes are implemented with current noise control technology to
the maximum feasible extent.
5C-46
-------
(RIO) Predicted Noise Levels for New Type Airplanes
Figures 19 (a), (b), and (c) show predicted noise levels for new
type design airplanes listed in Tables 6(a) and (b) compared with the
mean curves and the two sets of compliance noise level curves rep-
resenting available and future noise control technology. The data for
the thirty three listed airplanes are given in References 133.
The significance of the comparisons shown in Figures 19 is that
the data represent predicted noise levels of new types of airplanes
and two of the curves represent proposed requirements that must be
met after the indicated dates of application. First, airplanes whose
type certificates are applied for on or after 1980 and before 1985 would
be required to meet 80 FAR 36. Second, airplanes whose type certi-
ficates are applied for on or after 1985 would be required to meet
85 FAR 36 which is the estimated noise floor. That is, as perceived
at this time, noise levels lower than 85 FAR 36 are not feasible for
practical airplanes.
By comparison of the sideline noise levels of the airplanes with
the levels represented by the curves, it is seen that sixteen airplanes
comply with the mean, eight comply with 80 FAR 36, and three with
85 FAR 36. Similarly for takeoff; twenty airplanes comply with the
mean, eleven with 80 FAR 36, and seven with 85 FAR 36. And for
approach; ten airplanes comply with the mean, seven with 80 FAR 36,
and three with 85 FAR 36. Considering all three measuring points,
and exercising the 3/2 decibels tradeoff provision, nine airplanes can
comply with the mean, five with 80 FAR 36, and three with 85 FAR 36.
5C-47
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It is interesting to note by comparing Figures 5 and 19, that some
of the airplanes proposed as new type designs are predicted to pro-
duce noise levels greater than those of existing airplanes of compar-
able weight. For example, the four engine airplanes listed as new
type designs, but with existing type engines (Nos. 13 thru 16) have
predicted noise levels that exceed the levels of the B-747 airplanes
(powered by the same engines) listed in Table 4. Similarly, the
three-engine airplanes listed as new type designs, but with existing
type engines (Nos. 9 thru 12), exceed the levels of the DC-10 and
L-1011 airplanes listed in Table 4. These proposed new type design
airplanes obviously were not considered with full application of current
and available noise control technology.
The previous discussion clearly indicates that unless FAR 36 is
amended to require new type airplanes to be designed to include the
results of noise control RD&D, some manufacturers will continue to
be constrained only by the 69 FAR 36 levels. In other words, a volun-
tary program of noise reduction cannot be counted on to effect
significant source noise control. This does not rule out, however,
fortuitous noise reductions that result from efficient design practices.
This has occured in the past (e.g., high bypass ratio engines) and
no doubt will occur in the future. It only points out that noise control
and performance are not necessarily counteractive.
An explanation for the apparent noise floor violations (Nos. 7,
18, 26, 27, 28, 29, 30 and 33) is that the sources of the data may have
based their predictions on engine noise control technology and over-
looked or ignored the airframe noise floor. For example, airplane.
5C-48
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No. 7 represents the orginal NASA goal for the "Quiet Engine" which
was established before significant studies and tests were conducted on
the airframe noise floor concept. It is interesting, however, that
NASA has predicted that the propulsive noise floor will not "bottom
out" below the nonpropulsive noise floor. Furthermore, it should be
pointed out that airplane No. 8 is similar to the Airbus (A-300B),
listed as airplane No. 7 in Table 4, which has been certificated for
v noise in conformance with Annex 16. The tal eoff noise level of the
Airbus would lie approximate!; on the curve representing future
noise control technology. It may be that the initial model of the Air-
bus, with its high thrust to weight ratio and with the use of a substan-
tial amount of thrust cutback before reaching the 3.5 nautical mile
measuring point, has indeed reached the airframe noise floor during
a noise certification test demonstration for takeoff operations.
Another explanation, of course, is that the 85 FAR 36 (future tech-
nology) curve is simply too high. More definitive information should
be on hand for the next quinquennial review, at which time, the com-
pliance noise levels representing future technology can be adjusted.
5C-49
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(Rll) Recommendations for Noise Levels
In view of the previous discussion on noise levels, it is recom-
mended that §C36. 5 of FAR 36 be modified as appropriate to in-
clude the following requirements for complaince noise levels.
(a) Pre-1969 Technology Airplanes.
The compliance noise levels defined as 69 FAR 36, which are
existing requirements applicable to newly produced airplanes of older
type designs, are adequate, except for some acoustical changes, and
need not be modified.
(b) Current Technology Airplanes.
Compliance noise levels, applicable to new type design airplanes
for which an application for a type certificate is made on or after the
date this NPRM is issued, shall be chosen from the following four
options:
(1) ICAOWP/64 (Figures 3),
(2) FAAWP/39 (Figures 2),
(3) Mean (Figures 5),
(4) Modified Mean (Figures 8).
The above four sets of compliance noise levels are listed in order of
overall increasing stringency, although for some portions of the air-
plane maximum weight range this would not be true. However^ there
is not a great deal of difference in stringency between any one of the
candidates except for applications to general aviation aircraft. Any
one of the candidates (or a compromise among them} would effect sig-
nificant improvement and, therefore, would be an acceptable choice
for immediate application to current technology airplanes.
5C-50
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(c) Available Technology Airplanes.
Compliance noise levels, applicable to new type design airplanes
for which an application for a type certificate is made on or after
1 January 1980 and before 1985, shall be represented by the set of
curves in Figures 16 identified as "available" or 80 FAR 36.
(d) Future Technology Airplanes.
Compliance noise levels, applicable to new type design airplanes
for which an application for a type certificate is made on or after
1 January 1985, shall be represented by the set of curves in
Figures 16 identified as "future" or "85 FAR 36".
(e) Major Acoustical Change Airplanes.
Compliance noise levels and their effective dates, applicable to
airplanes with major acoustical changes to older type designs, shall
be equivalent to those prescribed for current technology airplanes.
5C-51
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S. Takeoff Test Conditions (§C36. 7 of FAR 36).
§C36. 7 of FAR 36 specifies takeoff test conditions relative to (1) the
power or thrust which must be maintained to a specific height above air-
port (HAA), (2) the permitted power or thrust cutback, (3) the airplane
speed, and (4) the airplane configuration. Experience as a result of
FAA noise certification tests since 1969 has shown that changes should
be made to items (1) and (2) above and that additional requirements
should be provided.
(SI) Power or Thrust
FAR 36 requires takeoff power or thrust be used from the start
of takeoff roll to 1000 feet HAA for two and three engine powered air-
planes and to only 700 feet HAA for airplanes powered by four or more
engines. The FAA noise certification tests show that it is both prac-
ticable and reasonable (as well as safer and less noise polluting) for
four engine current technology airplanes to reach 1000 feet HAA over
the takeoff measuring point. Therefore, the EPA believes that there
is no longer need for such discrimination. Consequently, it is rec-
ommended that the alternative height of 700 feet HAA, applicable to
airplanes powered by more than three engines, be eliminated. The
recommended wording for §C36. 7(b), therefore, is as follows:
(b) Takeoff power or thrust must be used from the start of
takeoff roll to the point at which a height of at least
1000 feet above the runway is reached.
5C-52
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(S2) Reduction of Power or Thrust
FAR 36 permits a power or thrust cutback to specified limits. The
original purpose for such a reduction was to establish a safe operating
procedure (and associated noise levels) for minimizing the noise im-
pact on near-downrange noise sensitive communities. However, that
particular procedure was never used to any significant extent in nor-
mal airline operations. The FAR 36 cutback procedure became little
more than a subterfuge to meet the required noise levels for some
airplanes that could not otherwise comply.
Several standard takeoff procedures, other than that of FAR 36
but suitable for safe operation of civil turbojet airplanes, are being
investigated by the EPA for use, as appropriate, to minimize the noise
exposure of noise sensitive communitites. The FAR 36 cutback pro-
cedure provides substantial thrust and noise reduction before the take-
off noise measuring point (3. 5 nautical miles) is overflown. Other
cutback procedures, however, with less thrust reduction may be more
effective in reducing the noise impact beyond 3. 5 nautical miles,
particularly in far-downrange noise sensitive communities and even
provide greater overall noise reduction.
The FAR 36 cutback procedure should remain as a compliance op-
tion in Takeoff Test Conditions (§C36. 7) until takeoff operating pro-
cedures are required by regulation for routine line operations. At
the very least, the FAR 36 cutback procedure approximates the max-
imum noise reduction that can be expected close to the airport by
safe operating procedures. However, since the FAR 36 cutback
procedure is not now used for routine takeoff operations nor antici-
5C-53
-------
pated for such use, it has little direct value for analyzing community
noise impact and for land use planning. Nevertheless, the FAR 36
cutback procedure will permit noise to be related to thrust and distance
which information is valuable for determining community noise impact
and for land use planning.
Consequently, it is recommended that the noise levels of airplanes
should be measured at the takeoff measuring point with the engines at
takeoff power or thrust for the purpose of providing information. If
the airplanes can comply with the noise level requirements at takeoff
power or thrust, then the cutback procedure would not be necessary.
If the airplanes can comply only with the cutback procedure, then addi-
tional testing at takeoff power or thrust should be required in order
to provide official and reliable information for use in analyzing com-
munity noise impact and for land use planning. The recommended
wording for §C36. 7(c), therefore, is as follows:
(c) Upon reaching the height specified in paragraph (b) of this
section, the power or thrust may not be reduced below that
power or thrust that will provide level flight with one engine
inoperative, or below that power or thrust that will main-
tain a climb gradient of at least 4 percent, whichever power
or thrust is greater. If compliance with the noise levels of
§C36. 5 is met with power or thrust reduction, additional
takeoff tests must be conducted without power or thrust re-
duction for information purposes.
5C-54
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(S3) Airplane Speed
FAR 36 requires the airplane minimum speed to be V2 + 10 knots
which must be attained as soon as practical after liftoff and maintained
throughout the takeoff noise test. Experience as a result of FAA
noise certification tests since 1969 has shown that this requirement
permits too wide a variation in the duration correction inherent in
EPNL. Also, for some airplanes, the all engines operating speed is
greater than V2 + 10. Therefore, it is recommended that §36. 7 (d)
be amended to read as follows:
(d) A speed of V2+10 knots or the all-engines-operating speed at
35 feet (for turbine engine powered airplanes) or 50 feet (for
reciprocating engine powered airplanes) whichever speed is
greater must be attained as soon as practicable after liftoff
and must be maintained throughout the takeoff noise test.
These tests must be conducted within tolerance speeds of +_ 3
knots and the noise values measured at the test day speeds
must be corrected to the acoustic day reference speeds.
(S4) Airplane Configuration
FAR 36 requires a constant takeoff configuration which must be
maintained throughout the takeoff noise test except that the landing
gear maybe retracted. There is no reason to change this requirement
at this time. However, if standard takeoff procedures for routine
operations become mandatory, this requirement may need revisions
in order to be compatible with the configurations used in the standard
procedures.
5C-55
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(S5) Horizontal Flight Procedures
If an airplane is relatively quiet, and/or has relatively good climb
performance, the airplane noise received at the sideline and takeoff
measuring points may be masked by the normal background noise.
That is, the signal to noise ratio (S/N) may be too small in one or
more of the required one third octave bands for satisfactory identifi-
cation and analysis of the airplane noise. In this event, a horizontal
flyover procedure at 1000 feet HAA should be conducted in lieu of the
requirements of §C36. 7(b) and (c) of FAR 36. The result usually
will be an adequate S/N, thus permitting satisfactory description of
the airplane noise. However, for the noise measurements to be
meaningful for certification and for community noise impact, they must
be related to the reference distance of 3. 5 nautical miles from brake
release and be corrected for both climb performance and speed.
A measure of the community noise impact caused by an airplane
is the population residing on the land contained within the boundary of
a specified equal noise level contour (the locus of points on the ground
which are exposed to a particular level of noise). The size of the
contour area is dependent upon both the noise energy and the perfor-
mance of the aircraft. The noise energy generated will be constant
for a given engine power or thrust setting («uch as takeoff or maxi-
mum climb) but the noise radiated to the ground also is dependent upon
the airline climb path and speed. At a given point on the extended
centerline of the runway, the steeper the climb, the higher the air-
plane, and the lower the noise level. Likewise; the greater the climb
speed, the shorter the duration of the noise, and the lower the Effec-
5C-56
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tive Perceived Noise Level.
The horizontal flight noise certification test, by itself, will not
provide sufficient information to make a judgment on the relationship
between airplane climb performance and noise exposure on the ground.
Two airplanes with the same engines at the same power setting would
be expected to produce about the same noise level over the measuring
station at a height of 1000 feet, even though the total weight of one
airplane might be substantially greater than the other. However, the
higher performance airplane (e.g., greater thrust/weight ratio) would
be expected, by virtue of its superior climb capability, to produce
smaller contour areas and, hence, less community noise impact.
This deficiency in the horizontal flyover procedure can be remedied
by a correction formula with factors relating to airplane performance
(both climb and speed) and the reference distance (3. 5 nautical miles
or 21266 feet). The development of the correction formula for climb
performance, applicable to turbojet - engine propelled airplanes, is
given in Figure 20. The resulting expression is:
C = 60 - 20 log [ (21266 - D35) sin ex + 35 ] (13)
where
o< = arcsine [ (R/C) / (VY) ] . (14)
The climb correction C is the value in decibels which, when added
algebraically to the measured noise level at 1000 feet (horizontal fly-
over), approximates the noise level at the 3.5 nautical miles (21266
feet) reference distance. The climb angle ex in degrees is dependent
upon the rate of climb (R/C) in feet per minute corresponding to the
airplane climb speed (VY) in feet per minute equivalent toV2+ 10 knots,
5C-57
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or the all-engines-operating speed whichever is greater.
The takeoff distance D35 (or D50 for propeller-driven airplanes) in
feet is the horizontal projection from brake release to a p\>int on
the runway at which the airplane is at a height of 35 feet above the
runway. The climb correction formula is based upon the assumption
that the angle of climb is relatively small which is appropriate for
all FAR 36 airplanes (the error is less than 0.5 dB at 12 degrees).
The climb correction C adjusts the measured noise level under
test conditions to the expected noise level at the reference distance
(3. 5 nm) from start-of-roll. In addition, under test conditions (hor-
izontal flight, maximum thrust at 1000 feet height above the test site)
the aircraft may accelerate over the test site at speeds greater than
the takeoff climb speed. Therefore, the duration of the sound (a
factor to be considered in human subjective reaction to noise and in-
cluded in EPNL), would be less under the horizontal flight path than
under the climb path. In order to make a proper assesment of the
noise measured under the simplified test conditions, the noise level
corrected for climb performance must be further corrected to account
for the change in speed which results in a change in noise duration.
The speed correction formula appropriate for this purpose is:
S - 10 log (VH / VY) "^ (15)
VH is the speed, averaged for all test flights, at the aircraft posi-
tion for which the tone corrected perceived noise level is maximum
with the aircraft operating at takeoff thrust and in horizontal flight
1000 feet over the measuring point. S is the speed correction in deci-
5C-58
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bels to be added algebraically to the measured noise level. The speed
correction S corrects the measured noise level to the EPNL levels
that would result from the actual climb speed.
In summary, the resulting performance correction, expressed in
dB, which should be added algebraically to the noise levels, expressed
in EPNdB, measured 1000 feet below a turbojet airplane in horizontal
flight at maximum thrust is:
P = C + S (For turbojet airplanes)
= 60-20 log[ (21266 - D35) sino:+ 35 ] + 10 log (VH / VY^ (16)
For propeller driven airplanes, the only change in the performance
correction P is the takeoff distance included in the climb correction C
as follows:
P = C + S (For propeller airplanes)
= 60-20 log [ (21266 - D50) sine* + 50 ] + 10 log (VH / VY^ (17)
The takeoff distance D50 in feet is the horizontal projection from
brake release to a point on the runway at which the airplane is a height
, of 50 feet above the runway. All other symbols have been defined
previously.
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T. Approach Test Conditions (§C36. 9 of FAR 36)
§C36. 9 of FAR 36 specifies approach test conditions relative to
(I1) the airplane's configuration, (2) the glide angle, (3) the approach
speed, and (4) the power or thrust. Experience as a result of FAA
noise certification tests conducted since 1969 has shown that the ap-
proach test conditions are satisfactory except for the configuration
requirements.
(Tl) Airplane Configuration
FAR 36 requires that the airplane's configuration used in showing
compliance with the noise levels of §36. 5 must be the same as used in
showing compliance with the airworthiness requirements. If more than
one configuration is certified for airworthiness, the configuration that
is most critical from a noise standpoint must be used. There is no
longer any purpose for determining the maximum noise levels on ap-
proach. On the contrary, it makes sense to require compliance for
one flap position less than the maximum landing flap setting certifi-
cated for airworthiness. The reason is that some airplanes now con-
duct normal landing operations at reduced flap setting for both noise
reduction and fuel conservation. All airplanes should be encouraged
to do so except when safety considerations dictate otherwise. Further-
more, the EPA has proposed the reduced flap setting procedure to the
FAA for promulgation as a regulation.
In consideration of the above, the recommended wording for
§C36.9(b) is as follows:
(b) The airplane's configuration must be that used in
5C-60
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showing compliance with the landing requirements in the
airworthiness regulations constituting the type certifica-
tion basis of the airplane. If more than one flap setting
is used in showing compliance with the landing require-
ments in the airworthiness regulations constituting the
type certification basis of the airplane, one flap position
less than the maximum certified must be used.
(T2) Glide Angle
FAR 36 requires that the approaches must be conducted with
a steady glide angle of 3 +_ 0. 5 degrees and must be continued to a
normal touchdown with no airframe configuration change. The wording
in §C36. 9{c) is clear and precise and changes are unnecessary.
(T3) Approach Speed
FAR 36 requires that a steady approach speed of not less than 1. 30
Vs + 10 knots must be established and maintained over the approach
measuring point. The wording in §C36. 9(d) is clear and precise and
changes are unnecessary.
(T4) Power or Thrust
FAR 36 requires that all engines must be operating at approxi-
mately the same power or thrust. The wording in §C36. 9(e^ is clear
and precise and changes are unnecessary.
5C-61
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6. HEALTH AND WELFARE AND COST CONSIDERATIONS
A. General
Fundamental to EPA's mandate, under the Noise Control Act of
1972, is the objective of attaining and maintaining a noise environment
that is consistent with public health and welfare requirements. In
striving for this objective, the agency is cognizant of FAA's require-
ment under Section 7 of the Act to take into account the availability of
technology and cost of compliance in arriving at the balance of judgment
as to the degree of noise suppression required.
The Noise Control Act of 1972 defines environmental noise as "the
intensity, duration, and the character of sounds from all sources". The
EPA has chosen the equivalent A-weighted sound pressure level (Leq)
as its basic measure for environmental noise (References 1, 4, 8, and
9). There are two time intervals of interest in the use of Leq for noise
impact assessment. The smallest interval of interest is one hour
usually considered the "design hour" of a day. The primary interval
of interest for residential land uses is a twenty four hour period, with
a weighting applied to nighttime noise levels to account for the in-
creased sensitivity with the decrease in background noise at night.
This twenty-four hour weighted equivalent level is denoted the Day-
Night Level (Ldn).
In its report to Congress (Reference 1) the EPA recognized that
the direct readily quantifiable effects of noise on public health and
welfare are: the potential for producing a permanent loss in hearing
acuity, interference with speech communications, and the generation of
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annoyance. The Levels Document (Reference 9) specifically identified
two long-term average levels of cumulative noise exposure as those
levels which should not be exceeded in order to protect the public
health and welfare with an adequate margin of safety:
A Day-Night Level (Ldn) no greater than 55 dB, to protect
against annoyance (including interference with speech com-
munication) and
An Equivalent Noise Level (Leq) no greater than 70 dB, to
protect against significant adverse effects on hearing.
Although the potential of indirect effects of noise exists, there are
not sufficient data to quantify them at this time.
The foregoing effects of noise can adversely influence an exposed
person's daily activity schedule and enjoyment. Typical results of the
primary adverse effects of noise are:
The relative attractiveness of real estate is degraded,
The delivery of public services is disturbed, e.g., interrup-
tions of educational instruction,
Interpersonal relationships are aggravated,
Continual or repetitive annoyance is manifested as tension
and stress, and
On the job performance, i.e., productivity, is diminished.,
These results demonstrate the insidious nature of noise in a person's
or community's physiological, social, and economic well-being.
The underlying concept for noise impact assessment is to express
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the change in human response expected from the people exposed to the
environmental noise exposure being considered. Three steps are in-
volved: (a) definition of initial acoustical environment; (b) definition of
final acoustical environment; (c) definition of the relationship between
the specified noise environment and the degree of its "impact" in
terms of i'ts expected human response.
The first two components of the assessment are entirely site or
system specific, relating to either estimates or measurement of the
environmental noise before and after the action being considered. The
same approach is used, conceptually, for the examination of a house
near a proposed road, the entire highway system, or the totality of
the nation's airports. The methodology for estimating the noise en-
vironment will vary widely with the scope and type of problem, but
the concept remains the same.
In contrast to the widely varying methodologies that may be used
for estimating the noise environment in each case, the relationships to
human response can be quantified by a single methodology for each site
or noise producing system considered in terms of the number of people
in occupied places exposed to noise of a specified magnitude. This
does not mean that individuals exhibit the same susceptibility to noise;
they do not. Even groups of people may vary in response depending on
previous exposure, age, socio-economic status, politicalcohesiveness
and other social variables. In the aggregate, however, for residential
locations the average response of groups of people is quite stably re-
lated to cumulative noise exposure as expressed in a measure such as
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the average yearly Ldn. The response considered is the general ad-
verse reaction of people to noise which consists of a combination of
such factors as speech interference, sleep interference, desire for a
tranquil environment, and the ability to use telephones, radio, or TV
satisfactorily. The measure of this response is related to the percen-
tage of people in a population that would be expected to indicate a high
annoyance to living in a noise environment of a specified level of ex-
posure.
The foregoing considerations permit the specification of numerical
values for noise levels in spaces devoted to various types of uses
which, if not exceeded, would provide entirely acceptable acoustical
environments. Thus, if those values are not exceeded, it could be
assumed that there would be no impact from environmental noise.
Specific noise criteria level values for those land uses or occupied
spaces generally encountered in noise impact assessments are pro-
vided in Table 7. Each of the levels provided in the table is speci-
fied as an outdoor noise level, even though the use of many of the
spaces is usually indoors. The noise reduction for typical building
construction has been used to arrive at an outdoor noise level that
would provide an acceptable indoor environment, since in any general
environmental impact study it is only an outdoor noise level that can
be predicted in any practical application. Also, it has been assumed
in the table that industrial and commercial applications are zero
impacted at any environmental noise level.
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Reduction of the noisiness of the environment will reduce the mag-
nitude of adverse effects such as those listed above. However, the
costs of these adverse effects are not well defined so that the benefits
of noise reduction cannot be readily related to compatible cost reduc-
tions. For example, Figure 21, taken from References 134 and 135,
is an estimate of the number of people on a national basis
impacted by aircraft noise. Population is presented as a function
of Ldn and Noise Exposure Forecast (NEF) but there is no accurate
quantification of the relative reduction in costs that would accrue in
removing one person from an Ldn 80 environment vis-a-vis removing
two persons from an Ldn 70 environment. That is, sufficient research
to quantify the cost benefits of noise reduction has not been performed
to date. Consequently, as in many environmental situations, not
having quantitative estimates of the benefits of noise reduction pre-
cludes analysis of the amount of environmental noise reduction that is
justified on a cost-benefit basis; therefore, the subsequent analyses
will use a cost-effectiveness framework.
A cost-effectiveness analysis can, however ^ yield valuable infor-
mation on the merits of the noise control options. To begin with,
it is necessary to consider the reduction in noise levels and the cor-
responding reduction in land areas exposed to specific noise levels.
Protection to the public health and welfare from aircraft noise
can be realized by combinations of reducing source noise and pro-
tecting noise sensitive receivers. Reduction of noise can be accom-
plished by replacing noisy aircraft with less noisy types, retrofitting
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existing aircraft with source noise abatement hardware, implementing
noise abatement takeoff and landing procedures, and exercising
airport operational control such as preferential runways, restric-
tions on flight frequencies, etc. Protection of noise sensitive receivers
can be accomplished through the soundproofing of residential and
other sensitive structures or through the relocation of existing incom-
patible land uses.
The technological practicability for the reduction of noise by
source and flight procedures control is limited. It should be
recognized also, that there exists a limit to the effectiveness of
soundproofing. For those receivers exposed to noise which cannot
be effectively reduced to compatible levels by soundproofing, the only
remaining alternative is relocation. The technological limitations of
soundproofing and the estimated costs are discussed in Reference 5.
The cost of achieving any given Ldn is defined as being the
cumulative costs of implementing noise source and flight procedures
control, airport restrictions, and the resource requirements for
soundproofing or relocating those noise sensitive receivers which
remain after the other options have been employed. The economic
problem to be solved is what combinations of these options result in
the most efficient or cost-effective, approach to realize several values
of Ldn (e.g., 80, 70, 60) around the nation's airports.
To implement a noise controlled airplane or modified airplane into
the existing fleet requires time to demonstrate acoustical and flight
performance, to certify the aircraft for safety, and to fabricate and
6-6
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install production kits. The time element plays an important role
in the dynamics of noise level achievement in that the total costs
of a noise control program, the fleet mix, levels of operations, and
urban growth vary with time. As an example, by the 1985 time period,
fleet noise levels are expected to be lower than those produced by
today's fleet because not as many, if any, pure turbojet-powered
aircraft will be operating in the fleet and the capacity represented
by these aircraft, and all other retired aircraft, will have been re-
placed by less noisy current technology aircraft. Lower fleet noise
levels translate into reductions in the areas of Ldn contours around
airports which in turn imply smaller impacted populations, if and
only if, land use development around airports does not result in
increased population densities surrounding the airport.
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B. Indicators of Noise Impact
Two single one-way runway airports were chosen to be indicators
of the noise impact resulting from the implementation of the various
options for compliance noise levels. The first runway pertains to
large air-carrier airports and the second to general aviation airports
as shown in Figure 22. The air-carrier airport is represented by
a runway 15, 000 ft in length enclosed by an imaginary rectangle whose
dimensions are 27,000 x 3,000 ft(2. 91 sq mi). The general aviation
airport is represented by a runway 6,000 ft in length enclosed by an
imaginary rectangle whose dimensions are 18, 000 x 3, 000 ft(l. 94 sq
mi). These dimensions were chosen to be compatible with the FAR 36
measuring points except that the takeoff point for the general aviation
airport was reduced from 3. 5 nautical miles to 2.0 nautical miles
to provide symmetry and to be more representative of the smaller land
areas characteristic of those airports.
The rectangles enclosing the airports can be considered as indica-
tors of land areas that, typically, suffer substantial noise impact.
Land areas which are noise impacted by aircraft operations should be
owned or controlled by airport authorities for airport functional pur-
poses; or the land should be used and can reasonably be expected to
continue to be used in a way which is compatible with the noise levels
to which it is exposed; or the development rights of such land should
be purchased such that only development compatible with the airport
noise levels is allowed.
It is generally agreed that a Ldn level of 75 dB is an unacceptable
6-8
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exposure level for people in normally constructed homes. A Ldn level
of 65 dB is a reasonable objective for airport neighborhood communi-
ties because present limited data indicate that, at some airports, a
Ldn contribution of noise from aircraft of less than 65 dB is difficult
to distinguish from other ambient noise, given the environmental noise
levels (other than from aircraft) around those airports. However, as
indicated in the Levels Document, effects from noise occur at Ldn
levels below 65 dB and further analysis is needed in the future to
refine further practical objectives for airport noise abatement.
The indicator rectangles serve the purpose of providing a standard
fence within which the effectiveness of the compliance noise level op-
tions may be compared in a meaningful and consistent manner. The
particular dimensions of the rectangles are significant because they
are compatible with the FAR 36 measuring points. Thus, the volumi-
nous amount of noise data, such as contained in Tables 3, can be
utilized directly without the need for lengthy computations. Further-
more, the rectangular dimensions are large enough to enclose
meaningful noise exposure contours and small enough to implement
noise control through compatible land use without experiencing un-
reasonable costs.
Many airports, of course, have more than one runway with mixed
directional operations and a single one-way runway airports may not
be a realistic representation of those airports. Nevertheless, for
airports with more than one runway, appropriate rectangles could be
superposed on each of the runways with the composite perimeter in-
dicative of a standard fence.
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Figures 23(a) through (e) permit comparisons to be made of the
effectiveness of the eight compliance noise levels in terms of specific
Ldn contours lying within the rectangle enclosing the air-carrier run-
way. For example, Figure 23(a) shows that, for 420 takeoffs and land-
ings each per day of a mix of aircraft containing 33. 3 percent 4-engine
aircraft, if all aircraft complied with the 69 FAR 36 levels, the Ldn
80 contour would lie within the rectangle. If all aircraft complied with
the future levels, the Ldn 70 contour would lie within the rectangle. On
the other hand, for the same number of operations per day of a mix of
aircraft containing no 4-engine aircraft, if all aircraft com-
plied with the 69 FAR 36 levels, the Ldn 78 contour would lie
within the rectangle. And, if all aircraft complied with the future
levels, the Ldn 67 contour would lie within the rectangle.
Figures 24(a) through (d) permit comparisons of the effectiveness
of the eight compliance noise levels to be made for cases of constant
percentage aircraft mix and variable operations per day. For example,
Figure 24(a) shows that if all aircraft complied with the levels of
1 69 FAR 36, 441 takeoffs and landings each per day would result in the
Ldn 80 contour lying within the rectangle. On the other hand, for the
Ldn 55 contour to lie within the rectangle, all aircraft would have to
comply with the future levels and the takeoff and landing operations
each per day would have to be reduced to 14.
Figures 25 (a) through (e) permit similar comparisons to the
foregoing to be made for general aviation aircraft. For example,
Figure 25(a) shows that if all aircraft complied with the levels of
69 FAR 36, 400 takeoffs and landings each per day would result in the
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Ldn 75 contour lying within the rectangle. On the other hand, for the
Ldn 55 contour to lie within the rectangle, the takeoff and landing opera-
tions per day would have to be reduced to 4. If, however^ all air-
craft could comply with the future levels, the number of operations
per day would not have to suffer as much of a reduction in order for
the Ldn contour to lie within the rectangle. Slightly less than 127
takeoffs and landings each per day would achieve that result.
Table 8 summarizes the relationships between the number of oper-
ations per day and the noise exposure contour levels that would lie
within the rectangles, for both air carrier and general aviation air-
ports, resulting from the implementation of each of the eight sets
of compliance noise levels. In regard to air carrier airports, Table
8(a) shows that for 420 takeoffs and landings, no proposed compliance
noise levels would permit the Ldn 65 contour to lie within the rec-
tangle. In other words, the Ldn 65 contour would lie outside the
rectangle and more than 3 square miles would have to be directed
to noise compatible land use. On the other hand, Table 8 (b) shows
that compliance with the future technology noise levels would result
in the Ldn 65 contour lying within the indicator rectangle when the
number of operations has been reduced from 441 to 141. For most
air carrier airport runways, 441 takeoff and landing operations each
per day are too large, while 141 or less are realistic. Certainly
having the Ldn 70 and Ldn 65 contours lying within three square
miles, due to 441 and 141 operations, respectively, are noteworthy
achievements especially since that accomplishment would result ex-
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clusively from source noise control. Additional noise abatement for
the same number of operations can be achieved by implementing
noise abatement approach and departure procedures.
In regard to general aviation airports, Table 8 (c) shows that
compliance with the available and future technology noise levels would
result in the Ldn 65 contours lying within the indicator rectangle for
all numbers of operations listed. Furthermore, for future technology
compliance, the Ldn 55 contour would almost lie within the indicator
rectangle when the number of operations per day has been reduced
from 400 to 127. For most general aviation airport runways, 127
takeoff and landing operations each per day for turbojet powered
airplanes and large propeller driven airplanes are more realistic
than 400.
For the case of general aviation airports, most of which are sited
in suburban or rural locations, the Ldn 55 goal is not too stringent.
It should be understood that while the airport neighborhood population
is less dense for general aviation airports compared with large air-
carrier airports, there are many more of the former and their neigh-
bors are exposed, in general, to less ambient noise and, therefore,
expect less noise intrusion.
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C. Costs
It is difficult to identify the costs, if any, to the aircraft manu-
facturers resulting from regulatory actions such as the proposed
amendments to FAR 36. Nevertheless, it should be expected that the
manufacturers' position will be that substantial increased costs will
be incurred with the extent depending upon the particular amendment.
The fact that such claims may be made does not mean they are valid.
Not only may the estimated costs be overly conservative but they may
not be properly counter balanced by the benefits that may accrue.
For example, the compliance noise levels representing current and
available technology are capable of being met by many aircraft being
produced today. The industry may claim, however, that if noise was
of no consideration, those airplanes could be produced and operated
»
at less cost. The weakness in this argument is that, to some extent
the lower noise levels of those quieter airplanes coincide with improved
performance. It is a well known fact that noise represents wasted
energy and properly designed noise control can direct some or all
of that energy to performance. The problems, of course, are to
determine whether the wasted energy is of sufficient magnitude to
be worth recovering and the recovery costs.
In addition, there is another aspect that is somewhat intangible
and difficult to quantify. Since noise represents a small percent of
the total energy, until comparatively recently it has been considered
by the aircraft and engine designers to be a second order effect in
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optimizing performance and, therefore, was neglected. As noise
became important, and techniques were developed for its abatement
and control, the designers found that there were benefits beyond
those that could be attributed to the relatively small energy transfer
of noise to performance. In other words, there was a fallout of
performance improvement resulting from the increased knowledge
of aircraft and engine design which can be attributed to the require-
ments for noise control. This phenomenon is a recent development
which should become more effective with time. The effectiveness
will depend upon the extent of the pressures (requirements) for noise
control up to the point where the noise floor is conclusively identified.
The costs of noise control by compatible land use are very high
and, in general, are the least cost-effective method of all. Those
*
costs, therefore, will be minimized when the control of aircraft noise
at the source results in Ldn contours lying within the indicator rec-
tangles that are as low in level as can be accomplished by safe,
technologically practicable, and economically reasonable techniques.
In regard to the amendments related to noise measurement and
evaluation, the costs identified with the closing of loopholes should
be dismissed as irrelevant. Other possible costs related to the im-
provement of procedures and techniques may be counter balanced by
the benefits of simplification and repeatibility. In any event, they are
difficult to quantify and may be negligible.
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7- CONCLUSIONS AND RECOMMENDATIONS
Source noise control is the application of basic design principles
or special hardware to the engine/airframe combination which will min-
imize the generation and radiation of noise. The technology of source
noise control is time-dependent in the sense that it is based upon the
results of past, present, and future programs of research, develop-
ment, and demonstration (RD&D) which can be classified as (1) current,
(2) available, or (3) future noise control technology. The applications
of source noise control should be directed to the following classifica-
tions of aircraft; (l)existing, (2) new production of older type designs,
(3) new production with acoustical changes to older type designs, and
(4) new production of new type designs.
The capability exists today for producing new airplanes that have
significantly lower noise levels than those required by the existing
FAR 36 regulations (69 FAR 36). Furthermore, noise control tech-
nology is sufficiently advanced such that technologically practicable and
economically reasonable compliance noise levels can be proposed to
be effective at time periods five to ten years in the future. The
fact that this capability exists, however, does not mean that it will
be implemented. Some motivation is necessary to insure that the avia-
tion community will use the technology and to continue to develop new
technology for future use. Regulations can be an effective technique
for exploiting noise control technology and, if properly constructed and
implemented, can provide the necessary incentive to insure that con-
tinuing effort is directed to technological advancements.
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FAR 36, which is a type certification regulation applicable to cer-
tain kinds of airplanes designated as types, has the following three
purposes:
(1) to provide requirements which will influence the design of air-
craft to include implementation of source noise control techno-
logy to the maximum extent feasible,
(2) the setting of standards and recommended practices for the
acquisition and reduction of aircraft noise and flight perfor-
mance data, and
(3) to provide meaningful noise levels for specific types of aircraft
which will be useful in predicting the noise impact in airport
neighborhood communities.
Since the promulgation of FAR 36 in 1969, noise control technology
has advanced, noise measurement and analysis equipment has improved,
and noise certification experience h?s identified significant weaknesses
in the original requirements. The objectives of proposed modifica-
tions (or amendments) to FAR 36, therefore, are to strengthen the
foregoing purposes in accordance with increased technological capa-
bility.
The recommendations for the proposed modifications are very com-
prehensive and, as a consequence, are provided as supplements to the
discussions in the appropriate portions of this project report. Detailed
recommendations, therefore, will not be presented here. However,
it is recommended that two separate NPRMs be proposed, which for
simplicity can be denoted as NPRM(A) and NPRM(B). The former
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would provide ten amendments pertaining principally to Appendix C
of FAR 36 and the latter to fourteen amendments pertaining principally
to Appendixes A and B of FAR 36.
The ten amendments recommended for inclusion in NPRM(A) are
summarized as follows:
(1) Amendments are applicable to propeller driven large airplanes
(maximum weight greater than 12, 500 Ib),
(2) Acoustical and major acoustical change approvals are included
(preamble only),
(3) Approved equivalent procedures may be used,
(4) Sideline measuring point for airplanes with more than three
engines must be 0. 25 nautical mile.
(5) Noise Levels
. Available Technology effective on 1 January 1980
. Future " " " 1 January 1985
' (6) Thrust reduction height for airplanes with more than three
engines must not be less than 1000 feet above the runway,
(7) If compliance is met with thrust reduction, additional tests .must
be conducted without thrust reduction and the noise levels re-
ported for information purposes,
(8) The flight demonstration tests must be conducted at a speed of
V2 + 10 knots or the all engines operating speed at 35 feet for
turbine engine powered airplanes (or 50 feet for reciprocating
engine powered airplanes) whichever speed is greater, within
a tolerance of + 3 knots.
(9) If signal to noise ratios are too small for satisfactory identifi-
7-3
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cation and analysis of the airplane noise, a specified horizontal
flyover procedure must be conducted, and
(10) If more than one flap setting is used to show compliance with the
landing requirements for airworthiness, one flap position less
than the maximum must be used for noise certification.
The fourteen amendments recommended for inclusion in NPRM(B)
are summarized as'follows:
(1) Microphone ground plane (terrain surrounding mircophone spe-
cified to be highly reflective),
(2) Adequate clear space (larger viewing angle to reduce possibility
of interference with noise measurements),
(3) Temperature and humidity (weather test conditions modified to
eliminate ambiguities and prevent erroneous results),
(4) Aircraft position data (tracking requirements for aircraft flight
path modified to be more practical and less costly),
(5) Tape recorder (specifications provided), »
(6) Microphone (ppecifications updated),
(7) Pre-emphasis/de-emphasis (specifications updated),
(8) Calibration Procedures (specifications updated, expanded and
reorganized),
(9) Windscreen (specifications provided),
(10) Analysis equipment (specifications updated and expanded),
(11) Reporting data (requirements clarified and expanded),
(12) Atmospheric attenuation of sound (updated to include use of
current SAE practice and obsolete method deleted),
(13) Detailed correction procedures (updated to include corrections*
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for test versus reference airspeed and thrust), and
(14) Noise evaluation (updated to include use of current SAE/ANSI
practices and standards). »
Furthermore, it is recommended that FAR 36 be reviewed every
five years or oftener. Appropriate sections of FAR 36 should be up-
dated where feasible to reflect the technology options and measure-
ment standards, practices, and procedures that are practicable and
appropriate for the aircraft types at that time. Consideration should
be given at each quinquennial review to the inclusion of the benefits
of previous experience in noise certification and on such matters as
whether the noise control technology is sufficiently advanced to justify
retrofitting operational aircraft and requiring newly produced aircraft
of older type designs to comply with more stringent noise levels.
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8. REFERENCES & BIBLIOGRAPHY
1. "Report on Aircraft/Airport Noise", Report of the Administrator
of the Environmental Protection Agency in Compliance with
Public Law 92-574, Senate Committee on Public Works, Serial
No. 93-8, August 1973.
2. "Legal and Institutional Analysis of Aircraft and Airport Noise
and Apportionment of Authority Between Federal, State, and
Local Governments", Report of Task Group 1, EPA NTID 73-2,
27 July 1973.
3. "Operations Analysis Including Monitoring, Enforcement,
Safety, and Cost", Report of Task Group 2, EPA NTID 73.3,
27 July 1973.
4. "impact Characterization of Noise Including Implications of
Identifying and Achieving Levels of Cumulative Noise Expo-
sure", Report of Task Group 3, EPA NTID 73.4, 27 July 1973.
5. "Noise Source Abatement Technology and Cost Analysis
Including Retrofitting", Report of Task Group 4, EPA NTID 73. 5,
27 July 1973.
6. "Review and Analysis of Present and Planned FAA Noise
Regulatory Actions and their Consequences Regarding Aircraft
and Airport Operation", Report of Task Group 5, EPA NTID 73. 6,
17 July 1973.
7. "Military Aircraft and Airport Noise and Opportunities for
Reduction without Inhibition of Military Missions", Report of Task
Group 6, EPA NTID 73. 7, 27 July 1973.
8. "Public Health and Welfare Criteria for Noise", EPA Tech-
nical Document 550/9-73-002, 27 July 1973.
9. "information on Levels of Environmental Noise Requisite to
Protect Public Health and Welfare with an Adequate Margin of
Safety", EPA Technical Document 550/9-74-004, March 1974.
10. "Aircraft and Airport Noise Regulations", Notice of Public
Comment Period, Federal Register (39 FR 6142), 19 February 1974.
11. "Noise Standards: Aircraft Type Certification", Federal Aviation
Regulations Part 36, Federal Register (34 FR 18364), 18 November
1969.
12. "Civil Aircraft Sonic Boom", Federal Aviation Regulations Part
91.55, Federal Register (38 FR 8051), 28 March 1973.
8-1
-------
13. "Noise Standards for Newly Produced Airplanes of Older Type
Designs", Federal Aviation Regulations Part 21.183(e) and Part 36
Amended, Federal Register (38 FR 29569), 26 October 1973.
14. "Acoustical Change Approvals", Federal Aviation Regulations
Part 36 Amended, Federal Resigter (39 FR 43830), 19 Dec.
1974.
15. "Noise Standards for Propeller Driven Small Airplanes", Federal
Aviation Regulations Part 21 and Part 36 Amended, Federal Reg-
ister (40 FR 1029), 6 January 1975.
16. "Report of the Special Meeting on Aircraft Noise in the Vicinity of
Aerodromes", International Civil Aviation Organization (ICAO),
Doc 8857, NOISE (1969), Montreal, 25 November - 17 December
1969.
17. "Aircraft Noise: Annex 16 to the Convention of International Civil
Aviation", International Civil Aviation Organization (ICAO), First
Edition, August 1971, Amendment 1, April 1973, Amendment 2,
April 1974.
18. "Amendment of Paragraph 2.1.2 in Chapter 2, Part II of Annex
16," ICAO CAN/4 - WP/6, Secretary, 9 October 1974.
19. "Report of the Committee by Working Group D on Development of
Proposals for Updating of the Annex 16 Noise Certification Stand-
ards for Subsonic Turbojet Aeroplanes of the Conventional Take-
Off and Landing Type", ICAO CAN/4-WP/20, Working Group D,
18 December 1974.
20. "Review of Annex 16 Noise Certification Standards for Subsonic
Turbojet Aeroplanes", ICAO CAN/4-WP/24, AACC, 30 December
1974.
21. "Compatibility of the Noise Certification Schemes Adapted to Var-
ious Categories of Aircraft", ICAO CAN/4-WP/28, France, 31
December 1974.
22. "Need for Approved Methods to Evaluate the Noise Environment
of Airports and the Contribution to be Made by Noise Certifica-
tion", ICAO CAN/4-WP/29, France, 31 December 1974.
23. "Comments on the Need for Acoustical Data in Addition to Noise
Certification Data", ICAO CAN/4-WP/31, Australia, 31 Decem-
ber 1974.
24. "Reflections on Noise Certification", ICAO CAN/4-WP/32, France,
6 January 1975, Addendum 27 January 1975.
8-2
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25. "Reflections on the Validity of the Various Parameters which
Affectthe Noise Produced by Aeroplanes", ICAO CAN/4-WP/33,
France, 9 January 1975.
26. "Comparison of Different Noise Certification Schemes", ICAO
CAN/4-WP/34, France, 15 January 1975.
27. "Methodology of Aircraft Noise Certification", ICAO CAN/4-
WP/35, France, 1 7 January 1975.
28. "A Scheme for Modification of Annex 16 Noise Level Require-
ments", ICAO CAN/4-WP/39, United States, 20 January 1975.
Also, "Subsonic Transport Category Large Airplanes and Sub-
sonic Turbojet Powered Airplanes, Proposed Noise Reduction
Stages and Acoustical Change Requirements", FAA NPRM 75-
37, 40 FR 51476, 5 November 1975.
29. "Comparison of 100 EPNdB Contours at Current and Proposed
Annex 16 Noise Levels", ICAO CAN/4-WP/40, United States,
20 January 1975.
30. "Review of Annex 16 Noise Certification Standards for Subsonic
Turbojet Airplanes", ICAO CAN/4-WP/44, Sweden, 22 Janu-
ary 1975.
31. "Standard for Future Aircraft Types", ICAO CAN/4-WP/45,
Belgium, 23 January 1975.
32. "Proposed Revision of the Temperature - Relative Humidity
Envelope for Noise Certification Measurements", ICAOCAN/4-
WP/47, United States, 27 January 1975.
33. "The United States Environmental Protection Agency Propo-
sal to Modify Annex 16 and FAR 36", ICAO CAN/4-WP/48,
United States, 27 January 1975.
34. "ICCAIA Proposed Recommendation to Modify Annex 16", ICAO
CAN/4-WP/59, ICCAIA, 28 January 1975.
35. "Committee on Aircraft Noise: Fourth Meeting", ICAOCAN/4-
WP/64, Report of Fourth Meeting Submitted to the Council,
13 February 1975; also Formal Report, Doc 9133, CAN/4,
26 March 1975; "Recommendations of the Fourth Meeting of
the Committee on Aircraft Noise for Amendment to Annex 16",
ICAO Letter with Attachment, AN 1/54. 8-75/117, 4 July 1975.
36.
No
Courses of Action on Agenda Item 3", ICAO CAN/4-Flimsey
\Io. 1, Secretary, 27 January 1975.
37. "Comparison of Data Points between Working Paper No. 39 and
the United Kingdom Proposal", ICAO CAN/4-Flimsey No. 2,
and hoc Drafting Group, 29 January 1975.
80
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38. "Proposed Modification of Appendix I of Appendix C to CAN/4-
WP/20 (Pages C-9 to C-66)", ICAO CAN/4-Flimsey No. 3,
ad hoc Working Group, 29 January 1975.
39. "Proposed EPNL Curves for Lateral, Approach, and Flyover
Noise Measurements", ICAO CAN/4-Flimsey No. 4, Secre-
tary, 29 January 1975.
40. "Recommendation 3/X - Noise Data for Estimation of Noise
Contours", ICAO CAN/4-Flimsey No. 5, Secretary, 29 Janu-
ary 1975.
41. "Insertion of a New Paragraph Under the Applicability Clause
of the Proposed New Certification Scheme", ICAO CAN/4-
Flimsey No. 9, United States, 30 January 1975.
42. "Proposed Acoustical Change Clause", ICAO CAN/4-Flimsey
No. 13, ad hoc Working Group, 3 February 1975, Revised
5 February 1975.
43. "Quantities and Units of Acoustics", ISO Re commendation / R31 /
Part VIII-1965, 1st Edition, by the International Organization
for Standardization, November 1965.
44. "Expression of the Physical and Subjective Magnitudes of Sound
or Noise", ISO Recommendation/R131-1959, 1st Edition, by
the International Organization for Standardization, September
1959.
45. "Field and Laboratory Measurements of Airborne and Impact
Sound Transmission", ISO Recommendation/R140 - 1960, 1st
Edition, by the International Organization for Standardization,
January 1960.
46. "Normal Equal-Loudness Contours for Pure Tones and Normal
Threshold of Hearing Under Free Field Listening Conditions",
ISO Recommendation/R226-1961, 1st Edition, by the Interna-
tional Organization for Standardization, December 1961.
47. "Preferred Frequencies for Acoustical Measurements", ISO
Recommendation/R266-1962, 1st Edition, by the International
Organization for Standardization, August 1962.
48. "Expression of the Power and Intensity Levels of Sound or
Noise", ISO Recommendation/R357-1963, Supplemental to ISO
Recommendation/R131-1959, 1st Edition, by the International
Organization for Standardization, December 1963.
49. "Measurement of Noise Emitted by Vehicles", ISO Recommen-
dation/R362-1964, 1st Edition, by the International Organiza-
tion for Standardization, February 1964.
8-4
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50. "Relation Between Sound Pressure Levels of Narrow Bands of
Noise in a Diffuse Field and in a Frontally-Incident Free Field
for Equal Loudness", ISO Recommendation/ R454 - 1965, 1st
Edition, by the International Organization for Standardization,
November 1965.
51. "Procedure for Describing Aircraft Noise Around an Airport",
ISO Recommendation/R507-1970, 2nd Edition, by the Interna-
tional Organization for Standardization, June 1970.
52. "Method for Calculating Loudness Level", ISO Recommenda-
tion/R532-1966, 1st Edition, by the International Organization
for Standardization, December 1966.
53. "Test Code for the Measurement of the Airborne Noise Emit-
ted by Rotating Electrical Machinery", ISO Recommendation/
R1680-1970, 1st Edition, by the International Organization for
Standardization, July 1970.
54. "Monitoring Aircraft Noise Around An Airport", ISO Recom-
mendation/R1761-1970, 1st Edition, by the International Or-
ganization for Standardization, June 1970.
55. "Assessment of Noise with Respect to Community Response",
ISO Recommendation/Rl966-1971, 1st Edition, by the Interna-
tional Organization for Standardization, May 1971.
56. "Assessment of Occupational Noise Exposure For Hearing Con-
servation Purposes", ISO Recommendation/R1999-1970, 1st
E Jition, by the International Organization for Standardization,
May 1971.
57. "Acoustics - Guide to the Measurement of Airborne Acoustical
Noise and Evaluation of its Effects on Man", ISO International
Standard/ISO 2204-1973, 1st Edition, by the International Or-
ganization for Standardization, 1973.
58. "Description and Measurement of Physical Properties of Sonic
Booms", ISO International Standard/ISO 2249-1973, 1st Edi-
tion, by the International Organization for Standardization, 15
March 1973.
59. "Measurement of Noise Emitted By Aircraft", 3rd Draft Rec-
ommendation, Proposed by ISO/TC 43/W.G. 12 & 13 (Laubert)
62 of the International Organization for Standardization, date
unknown.
60. "D and N-Weighted Sound Levels", by ISO/TC 43 - Acoustics
Committee of the International Organization for Standardiza-
tion, July 1968.
8-5
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61. "Recommendations for Sound Level Meters", Publication 123,
by the International Electrotechnical Commission, 1961.
62. "Standard Atmospheric Conditions for Test Purposes", Publi-
cation 160, by the International Electrotechnical Commission,
1963.
63. "Precision Sound Level Meters", Publication 179, 2nd Edition,
by the International Electrotechnical Commission, 1973.
64. "Precision Sound Level Meters: Additional Characteristics for
the Measurement of Impulsive Sounds - First Supplement to
Publication 179 (1973)", Publication 179A, by the International
Electrotechnical Commission, 1973.
65. "Octave, Half-Octave and Third-Octave Band Filters Intended
for The Analysis of Sounds and Vibrations", Publication 225,
by the International Electrotechnical Commission, 1966.
66. "Direct Recording Electrical Measuring Instruments and Their
Accessories", Publication 258, by the International Electro-
technical Commission, 1968.
67. "Sound System Equipment - Part I: General", Publication 268-1,
by the International Electrotechnical Commission, 1968.
68. "International Electrotechnical Vocabulary: Electro-Acoustics",
2nd Edition, Reference No. 50 (08), by the International Elec-
trotechnical Commission, 1960.
69. "Noise Measurements for Aircraft Design Purposes Including
Noise Certification Purposes", CAP 335, by The London Board
of Trade, 1970.
70. "Acoustical Terminology (Including Mechanical Shock and Vi-
bration)", SI. 1-1960, Sponsored by the Acoustical Society of
America and Approved by American Standard Association, (cur-
rently ANSI), 25 May 1960.
71. "Method for the Physical Measurement of Sound", SI. 2-1962,
Sponsored by the Acoustical Society of America and Approved
by the United States of America Standards Institute (currently
ANSI), 20 Aug. 1962.
72. "Specification for Sound Level Meters", ANSI SI. 4-1971, by
the American National Standards Institute, 27 April 1971..
73. "Preferred Frequencies and Band Numbers for Acoustical Meas
urements", SI. 6-1967, Sponsored by the Acoustical Society of
America and Approved by the United States of America Stand-
ards Institute (currently ANSI), 17 March 1967.
8-6
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74. "Preferred Reference Quantities for Acoustical Levels", SI. 8-
1969, Sponsored by the Acoustical Society of America and the
American National Standards Institute (ANSI), 24 February 1969.
75. "Methods for Calibration of Microphones", SI. 10-1966, Spon-
sored by the Acoustical Society of America and approved by
the United States of America Standards Institute (currently
ANSI), 14 Mar. 1966.
76. "Octave, Half-Octave, and Third-Octave Band Filter Sets",
SI. 11-1966, Sponsored by the Acoustical Society of America
and Approved by the American Standards Association (cur-
rently ANSI), 4 May 1966.
77. "Specifications for Laboratory Standard Microphones", SI.12-
1967, Sponsored by the Acoustical Society of America and Ap-
proved by the United States of America Standards Institute
(currently ANSI), 5 Oct. 1967.
78. "Methods for the Measurement of Sound Pressure Levels",
SI. 13-1971, Acoustical Society of America - Secretariat, Ap-
proved by the American National Standards Institute (ANSI),
14 July 1971.
79. "USA Standard Procedure for the Computation of Loudness of
Noise", S3.4-1068, Sponsored by the Acoustical Society of
America, Approved by the United States of America Standards
Institute (currently ANSI), 26 March 1968.
80. "Letter Symbols for Acoustics", Y10. 11-1953, Sponsored by
the American Society of Mechanical Engineers and Approved
by the American Standards Association (currently ANSI), 21
Dec. 1953.
81. "Method for Specifying the Characteristics of Analyzers Used
for The Analysis of Sounds and Vibrations", Z24.15-1955, Spon-
sored by the Acoustical Society of America and Approved by
the United States of America Standards Institute (currently
ANSI), 4 Feb. 1955.
82. "Sound Level Meters", Draft proposal DOC/S1/169 to ANSI,
Sponsored by the Acoustical Society of America, Oct. 1969.
83. "Methods for the Measurement of Sound Pressure Levels",
Draft proposal DOC/LB/SI/175 to ANSI, Sponsored by the
Acoustical Society of America, 2 March 1970.
84. "Criteria for Background Noise in Audiometer Rooms", Draft
proposed revision of American Standard Criteria DOC/LB/S3/
175 to ANSI, May 1970 (app. ).
8-7
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85. "Test Code for the Measurement of Sound From Pneumatic
Equipment", First Edition, proposal sponsored by the Com-
pressed Air and Gas Institute (CAGI) and submitted to the
United States of America Standards Institute (currently ANSI),
1969.
86. "Measurement of Aircraft Exterior Noise in the Field", Draft
ARP 796, Society of Automotive Engineers, 24 April 1974.
87. "Definitions and Procedures for Computing the Perceived
Noise Level of Aircraft Noise", ARP 865A, prepared by Com-
mittee A-21-Aircrat Noise Measurement, Society of Automo-
tive Engineers, Revised 15 Aug. 1969.
88. "Standard Values of Atmospheric Absorption as a Function of
Temperature and Humidity for Use in Evaluating Aircraft Fly-
over Noise", ARP 866, prepared by Committee A-21-Aircraft
Exterior Noise Measurement, Society of Automotive Engineers,
31 Aug. 1964.
89. "Definitions and Procedures for Computing the Effective Per-
ceived Noise Level for Flyover Aircraft Noise", ARP 1071,
prepared by Committee A-21-Aircraft Noise Measurement,
Society of Automotive Engineers, June 1972.
90. "Frequency Weighting Network for Approximation of Perceived
Noise Level for Aircraft Noise", ARP 1080, prepared by Com-
mittee A-21-Aircraft Exterior Noise Measurement, Society of
Automotive Engineers, 1 July 1969.
91. "Recommended Procedure for Presenting and Measuring Air-
craft Noise in Testing of Human
of Automotive Engineers, (date)
craft Noise in Testing of Human Subjects", ARP 1157, Society
92. "Effective Perceived Noise Level Determination by Direct Sub-
ject Judgement Test", ARP 1158, Society of Automotive En-
gineers, (date).
93. "Use of Aircraft Noise Exposure Information in Land Use Plan-
ning", ARP 1164, Society of Automotive Engineers, (date).
94. "A Technique for Narrow Band Analysis of a Transient", AIR
817, prepared by Committee A-21-Aircraft Exterior Noise
Measurement, Society of Automotive Engineers, 28 Feb. 1967.
95. "Methods of Comparing Aircraft Takeoff and Approach Noise",
AIR 852, prepared by Committee A-21-Aircraft Exterior Noise
Measurement, Society of Automotive Engineers, 30 June 1965.
8Q
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96. "Jet Noise Prediction", AIR 876, prepared by Committee A-21-
Aircraft Exterior Noise Measurement, Society of Automotive
Engineers, 10 July 1965.
97. "Determination of Minimum Distance from Ground Observer to
Aircraft for Acoustic Tests", AIR 902, prepared by Committee
A-21-Aircraft Exterior Noise Measurement, Society of Auto-
motive Engineers, 15 May 1966.
98. "Method for Calculating the Attenuation of Aircraft Ground to
Ground Noise Propagation During Takeoff and Landing", AIR
923, prepared by Committee A-21-Aircraft Exterior Noise
Measurement, Society of Automotive Engineers, 15 Aug. 1966.
99. "Aircraft Noise Research Needs", AIR 1079, prepared by Com-
mittee A-21-Aircraft Noise Measurement, Society of Automo-
tive Engineers, May 19 72.
100. "House Noise-Reduction Measurements for Use in Studies of
Aircraft Flyover Noise", AIR 1081, prepared by Committee
A-21-Aircraft Noise Measurement, Society of Automotive En-
gineers, Oct. 1971.
101. "Procedures for the Measurement of Aircraft Noise and Air-
craft Noise Environments with Respect to Perceived Noisiness",
AIR 1094, Society of Automotive Engineers, (date).
102. "Procedures for Developing Aircraft Noise Exposure Contours
Around Airports", AIR 1114, Society of Automotive Engineers,
(date).
103. "Evaluation of Headphones for Demonstration of Aircraft Noise",
AIR 1115, prepared by Committee A-21-Aircraft Noise Meas-
urement, Society of Automotive Engineers, 1 Dec. 1969.
104. "Comparison of Ground-Runup and Flyover Noise", AIR 1216,
prepared by Committee A-21-Aircraft Noise Measurement,
Society of Automative Engineers, April 1972.
105. "Helicopter and V/STOL Aircraft Noise Measurement Prob-
lems", AIR 1286, prepared by Helicopter and V/STOL Noise
Subcommittee of Committee A - 21 - Aircraft Noise Measure-
ment Society of Automotive Engineers, April 1973.
106. "Qualifying a Sound Data Acquisition System", SAE Recommen-
ded Practice/J 184, Approved as ANSI S6.1-1973 by the Amer-
ican National Standards Institute, Sponsored by the Society for
Automotive Engineers (SAE), 18 October 1973.
8-9
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107. "Laboratory Measurement of Airborne Sound Transmission
Loss of Building Partitions", Standard Recommended Practice/
E90-70, American Society for Testing and Materials (ASTM),
6 November 1970.
108. "Electro-Acoustical Performance Requirements for Aircraft
Noise Certification Measurements", International Electrotech-
nical Commission (IEC) Document 29 C (Secretariat) 19, Draft,
1974.
109. "Proposed ARP 1264: Airplane Flyover Noise Analysis Sys-
tems Used for Effective Perceived Noise Level Computations"
(DRAFT) Society of Automotive Engineers, 11 January 1973.
110. "Definitions and Procedures for Computing the Effective Per-
ceived Noise Level for Flyover Aircraft Noise", Society of
Automotive Engineers, ARP 1071, October 1973; also American
National Standards Institute, ANSI S6.4-1973, 10 July 1973.
111. "Notification that SAE ARP 1071 has been Adopted as an ANSI
Standard", Letter from William J. Toth (SAE) to Russell Train
(EPA), 18 July 1975.
112. "Recommendation that all Federal Agencies Use Leq/Ldn as
Environmental Noise Descriptors", Letter from Russell Train
(EPA) to Heads of Federal Agencies, 16 August 1974.
113. "Technical Review of Federal Aviation Regulation Part 36-Noise
Standards: Aircraft Certification", Bolt, Beranek and New-
man, Inc., Report No. 2943, March, 1976.
114. "Type Certification, Agency Order 8110-4"; Chapter 8, Noise
Type Certification, FAA Office of Environmental Quality,
DRAFT, 11 July 1975.
115. J.B. McCollough and Harold C. True, "Effect of Temperature
and Humidity on Aircraft Noise Propagation", Federal Avia-
tion Administration Report No. FAA-RD-75-100, September
1975.
116. "Noise Type Certification Test and Data Correction Proce-
dures", Federal Aviation Administration, Undated Draft Re-
port on Project No. AEQ-75-5-R.
8-10
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117. "Noise Standards for Propeller Driven Small Airplanes", EPA
Recommended Notice of Proposed Rulemaking, Federal Register
(40 FR 1061), 6 January 1975.
118. "Noise Certification Rule for Propeller Driven Small Airplanes",
EPA Project Report, 25 November 1974.
119. Noise Levels for Existing Aircraft.
(a) "Aircraft Noise Levels", Department of Transportation,
Federal Aviation Agency, Advisory Circular AC No. 36-LA,
21 July 1975.
(b) J. Streckenbach, "Aircraft Noise Summary", Boeing Fold-
Up Card, November 1974.
(c) "Noise Standards for Civil Subsonic Turbojet Engine-
Powered Airplanes (Retrofit and Fleet Noise Level)",
Environmental Protection Agency Project Report, 16 De-
cember 1974.
(d) "Aircraft Noise Certification Rule for Supersonic Civil Air-
craft", Environmental Protection Agency Project Report,
24 January 1975.
(e) "Noise Levels for Lockheed L-1011 Airplanes", Briefing
Data Received 2 October 1975.
(f) "Design Changes Slow Falcon 50 Schedule", Aviation Week
and Space Technology, 5 May 1975.
(g) "Reengined Jet Star Investment Kept Low", Aviation Week
and Space Technology, 11 August 1975.
(h) "Specifications", Aviation Week & Space Technology", 17
March 1975.
(i) H. Pearson, Rolls-Royce (1971) Ltd., "The Development
of Propulsion Systems for Air Transport", SAE, AIAA,
ASME Conference Proceedings, Air Transportation Con-
ference, Washington, D. C. , May 31 - June 2, 1972.
(j) "Concorde Supersonic Transport Aircraft", Final Environ-
mental Impact Statement, September 1975.
(k) "VFW 614", Brochure by Fokker-VFW International
(1) "F28", Brochure by Fokker-VFW International
8-11
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120. W. C. Sperry, "Analysis of Noise Levels for Existing and Fu-
ture Airplanes in View of Modifications to Federal Aviation
Regulations Part 36", Proceedings 1975 International Conference
on Noise Control Engineering, Sendai, Japan, 27 August 1975.
121. J.O. Powers, "Future Noise Requirements for Commercial
Aircraft", AIAA Paper No. 73-1290, AIAA/SAE 9th Propulsion
Conference, Las Vegas, 5-7 November 1973.
122. J.R. Thompson, "A Constant Technology Approach to Noise Reg-
ulation", Lockheed-California Study, 30 May 1974, and Letter
from H. Drell (Lockheed) to W. C. Sperry (EPA), 17 February
1975.
123. A. L. McPike, "Possible Modifications to FAR Part 36 and
Annex 16", Informal Document presented to W. C. Sperry by
A. L. McPike on 14 February 1975, 28 October 1974.
124. A. L. McPike, "Maximum Air Transportation Service with Min-
imum Community Noise", AIAA Paper No. 73-796, St. Louis,
Missouri, 6-8 August 1973.
125. A. L. McPike, "Toward Reducing the Impact of Aircraft Noise-
A New Approach to Aircraft Noise Certification", Douglas Paper
6371, American Society of Civil Engineers, San Francisco, 24-
26 March 1975.
126. "Civil Aviation Research and Development Policy Study", Joint
DOT-NASA: Report, DOT-TST-10-4 and NASA SP-265; Sup-
porting Papers, DOT-TST-10-5 and NASA SP-266; March 1971.
127. "Aircraft Noise Reduction Technology", A Report by the National
Aeronautics and Space Administration to the Environmental
Protection Agency for the Air craft/Airport Noise Study, NASA
TMX-68241, 30 March 1973.
128. H.H. Hubbard and D. J. Maglieri, "A Brief Review of Air Trans-
port Noise", Noise Control Engineering, November-December
1974.
129. "Aeronautical Propulsion", Conference Proceedings, NASA
Lewis Research Center, 13-14 May 1975.
130. Progress in Aircraft Noise Reduction.
(a) V. L. Blumenthal et al, "Aircraft Community Noise Re-
search and Development: A Historical Overview", J.
Acoust. Soc. Am., July 1975.
(b) M.D. Nelson and V. E. Callaway, "Development of Noise
Reduction Concepts for 707 Airplane", J. Acoust. Soc. Am
July 1975. • '
8-12
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(c) C.L. Arctander et al, "Development of Noise Reduction
Concepts for 727 and 737 Airplanes", J. Acoust. Soc. Am.,
July 1975.
(d) R.L. Frasca, "Noise Reduction Programs for DC-8 and
DC-9 Airplanes", J. Acoust. Soc. Am., July 1975.
(e) C.A. Sekyra et al, "Validity of Aircraft Noise Data", J.
Acoust. Soc. Am., July 1975.
131. Aerodynamic Noise Analysis and Predictions.
(a) J. S. Gibson, "Non-Engine Aerodynamic Noise Technology
and Impact", Lockheed-Georgia Co. Information Brief
IB7301, 6 April 1973.
(b) J. S. Gibson, "The Ultimate Noise Barrier-Far Field
Radiated Aerodynamic Noise", Inter-Noise '72 Proceedings,
Washington, D. C., 4-6 October 1972.
(c) J. S. Gibson, "Non-Engine Aerodynamic Noise: The Limit
To Aircraft Noise Reduction", Inter-Noise 73 Proceedings,
Lyngby, Denmark, 22-24 August 1974.
(d) J. D. Revell, "The Calculation of Aerodynamic Noise Gen-
erated by L?rge Aircraft at Landing Approach", Acoustical
Society of America, New York, N. Y. , 26 April 1974.
(e) I.C. Cheeseman, "Airframe Noise", Flight International,
16 August 1973.
(f) H.G. Morgan and J. C. Hardin, "Airframe Noise-The Next
Aircraft Noise Barrier", AIAA Paper No. 74-949, Los
Angeles, CA., 12-14 August 1974.
(g) J. S. Gibson, "Recent Developments at the Ultimate Noise
Barrier", ICAS Paper No. 74-59, Haifa, Israel, 25-30
August 1974.
(h) J. C. Hardin et al. "Predictions of Airframe Noise", NASA
Technical Note, NASA TN D-7821, February 1975.
(i) P. Fethney, "An Experimental Study of Airframe Self-
Noise", AIAA Paper 75-511, Hampton, Va., 24-26 March
1975.
(j) G.J. Healy, "Aircraft Far-Field Aerodynamic Noise-Its
Measurement and Prediction", AIAA Paper 75-486, Hamp-
ton, Va., 24-26 March 1975.
8-13
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(k) T.W. Putnam et al, "Measurements and Analysis of Air-
craft Airframe Noise", AIAA Paper 75-510, Hampton, Va.,
24-26 March 1975.
(1) J.G. Shearin andP.J. Block, "Airframe Noise Measure-
ments on a Transport Model", AIAA Paper 75-509, Hamp-
ton, Va., 24-26 March 1975.
(m) D.J. Fratello and J. G. Shearin, "A Preliminary Investi-
gation of Remotely Piloted Vehicles for Airframe Noise
Research", AIAA Paper 75-512, 24-26 March 1975.
(n) H.S. Ribner, "Jet and Airframe Noise", AGARD Lecture
Series No. 77, AGARD-LS-77, June 1975.
132. Predicted Noise Levels for Major Acoustical Change Aircraft.
(a) "Predicted Noise Levels for Refanned Aircraft", Letter
fromW.H. Roudebush (NASA) to W. C. Sperry (EPA), 11
February 1975, Revised by Briefing Charts, 25 February
1975, and "Initial Report on DC-9 Refan Flight Test Pro-
gram", W. H. Roudebush, 26 June 1975.
(b) K. L. Abdalla and J. A. Yuska, "NASA Refan Program
Status", Society of Automotive Engineers, Air Transpor-
tation Meeting, SAE 750592, Hartford, 6-8 May 1975.
(c) "Noise and Performance Estimates", Letter from Ray E.
Bates, (Douglas) to J. C. Schettino (EPA), 16 April 1975,
and Letter from A. L. McPike (Douglas) to W.C. Sperry
(EPA), 25 July 1975.
(d) "Recommendation for Revised Annex 16 Scheme and Noise
Level Requirement", The Boeing Co., Draft 12 December
1974.
(e) "Information on 727-300B and 7X7 Airplanes", The Boeing
Co., Briefing to EPA on 14-15 May 1975, 5 June 1975,
and Letter from R. E. Russell and H. W. Withington
(Boeing) to W. C. Sperry (EPA), 4 June 1975, and 15 July
1975.
(f) "BAG One-Eleven 700 Series", British Aircraft Corpora-
tion Brochure TSW 2508, August 1974.
133. Predicted Noise Levels for New Type Design Aircraft.
(a) "Information on 727-300B and 7X7 Airplanes", The Boeing
Co., Briefing to EPA on 14-15 May 1975, 5 June 1975,
and Letter from R. E. Russell and H. W. Withington
(Boeing) to W. C. Sperry (EPA), 4 June 1975, and 15 July
Jty i o« ••
8-14
-------
(b) "BAG One-Eleven 800 Series", British Aircraft Corpora-
tion Briefing Paper Received 20 May 1975.
(c) "New Wide-Body Transport Plan Evolving", Aviation Week
& Space Technology, 13 October 1975.
(d) "DC-X-200 Melds DC-10, New Technology", Aviation Week
and Space Technology, 20 October 1975.
(e) "1977 NASA Authorization", Hearings before the Subcom-
mittee on Aviation and Transportation R&D of the Com-
mittee on Science and Technology, U. S. House of Repre-
sentatives, October 15, 16, November 3, 4, 5, and 10,
1975, No. 34, Volume II, Part 1.
(f) G.D. Brewer, "Liquid Hydrogen--A Logical Choice to Fuel
Future Commercial Airplanes", Lockheed California, Co.,
ICAO Bulletin, February 1976.
(g) "CFM 56 Briefings", CFM International, S.A., May 1976.
(h) "Canadair Sees Big Lear Star 600 Market", Aviation Week
and Space Technology, 26 July 1976.
134. C. Bartel et al, "Aircraft Noise Reduction Forecast Volume I
- Summary Report for 23 Airports", Department of Transpor-
tation, DOT-TST-75-3.
135. C. Bartel et al, "Airport Noise Reduction Forecast, Volume
II - NEF Computer Programs Description and Users' Manual",
Department of Transportation, DOT TST-75-4, October
1974.
136. C. Bartel et al, "National Measure of Aircraft Noise Impact
Through the Year 2000", Environmental Protection Agency
Report, EPA 550/9-75-024, June 1975.
8-15
-------
o
o
-
TO
a.
E
CD
20
40 60
Relative Humidity, %
100
FIGURE 1. COMPARISON OF ISO AND ICAO PROPOSALS FOR TEMPERATURE AND
RELATIVE HUMIDITY TEST CONDITIONS.
9-1
-------
120
110
co
z
a.
ill
>
s 10°
o
z
CO ID
ro >
LU
o
oc
LU
a.
LU
CJ
LU
96 FAA WP/39 (3 & 4 Engines)
Formulas Given in Table 2
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 2. COMPLIANCE NOISE LEVELS PROPOSED BY FAA.
_..- (a) SI-DELINE AT 0.35 NAUTICAL MILE.(463 METERS).
-------
120
cp
CO
m
a.
LU
_T
LU
LU
_l
UJ
00
O
z
a
LU
O
cc
LU
a.
LU
O
LU
110
FAA WP/39 (3 & 4 Engines)
FAAWP/39 (2 Engines)
Formulas Given in Table 2
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 L8
200 300
500
1000
FIGURE 2. COMPLIANCE NOISE LEVELS PROPOSED BY FAA.
(b) TAKEOFF AT 3.5 NAUTICAL MILES (6,482 METERS).
-------
9
m
O_
LLJ
to
O
z
Q
111
O
QC
111
O.
LLJ
o
111
111
120
110
100
90
80
70
I I IT
i- 102 69 FAR 36
98 FAA WP/39 (All Engines)
1 I I
I I IT
J I
I l I
II
Formulas Given in Table 2
I
I
108 -
I I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 2. COMPLIANCE NOISE LEVELS PROPOSED BY FAA.
' (c) APPROACH AT 1.0 NAUTICAL MILE (1,852 METERS).
-------
CD
Ul
120
110
CD
z
0.
LLJ
LLJ
LLJ
_l
$ 1°°
o
z
o
LLJ
o
QC
til
a.
CJ
111
90
80
70
I II T
-102 69 FAR 36
I I
I I IT
96 ICAO WP/64 (All Engines)
& FAA WP/39 (4 Engines)
I I I I
I
I I I I
I T
108 -
Formulas Given in Table 2
I I
I I I I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 3. COMPLIANCE NOISE LEVELS PROPOSED BY ICAO.
(a) SIDELINE AT 450 METERS (0.24 NAUTICAL MILE).
-------
120
110
CO
O5
0.
01
01
01
w 100
Q
LU
01
O
cc
01
a.
LU
o
Ol
90
80
70
93
89
I I IT
69 FAR 36
I I TT
ICAOWP/64 (All Engines)
I
_L
I I 1 l
Formulas <3iven in Table 2
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 3. COMPLIANCE NOISE LEVELS PROPOSED BY ICAO.
(b) TAKEOFF AT 6,500 METERS (3.5.1 NAUTICAL MILES).
-------
CO
m
•a
a.
LU
LU
HI
_l
HI
CO
O
z
Q
HI
LU
CJ
DC
LLJ
a.
CJ
120
110
100
90
80
70
- 102
98
I I IT
69 FAR 36
ICAO WP/64 (All engines)
& FAAWP/39 (All Engines)
I
I I IT
I
I
i I I I
I I IT
Formulas Given in Table 2
i 1 I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 3. COMPLIANCE NOISE LEVELS PROPOSED BY ICAO.
'' (c) APPROACH AT 2,000 METERS (1.08 NAUTICAL MILES).
-------
CD
03
00
-o
LU
LU
_J
LU
6
o
LU
>
LU
O
oc
LU
Q_
LU
O
LU
LL
LU
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 4. AIRPLANE NOISE LEVELS COMPARED TO FAA AND ICAO RECOMMENDATIONS.
(a) SIDELINE (2 ENGINES) AT 0.25 NAUTICAL MILES (463 METERS).
-------
120
CD
cb
CD
Z
o.
LU
LU
LU
o
z
0
O
-------
cp
o
CD
•o
a.
UJ
ui
LJJ
en
O
Z
UJ
o
CC
LJJ
a.
UJ
I
UJ
UJ
110
100
90
80
1 1 1 1
102 69 FAR 36
96 FAA WP/39
- & ICAO WP/64
1
1 1
o
16
15
1
1
1 1 1 1
Note:
Data Measured at 0.35 NM
Increased 3.5 dB for
0.25 NM Applicability.
I.D. Nos. Given in Tables 3
1 1 1
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 4. AIRPLANE NOISE LEVELS COMPARED TO FAA AND ICAO RECOMMENDATIONS.
(c) SIDELINE (4 ENGINES) AT 0.25 NAUTICAL MILE (463 METERS).
-------
120
CD
•o
o.
LU
LU
111
en
O
z
o
tO LU
^ >
~* LU
O
tr
o
LU
u_
110
100
I.D. Nos. Given In Tables 3
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 4. AIRPLANE NOISE LEVELS COMPARED TO FAA AND ICAO RECOMMENDATIONS.
(d) TAKEOFF (2 ENGINES) AT 3.5 NAUTICAL MILES (6,482 METERS).
-------
120
cp
Ni
m
T3
LU
>
HI
O
z
Q
LU
O
cc
LU
a.
LU
O
LU
110
90
80
70
I I I I
93 69 FAR 36
90 FAA WP/39
89 ICAO WP/64
1 I
I I IT
Q56
1
I
I
I I I l
41
I.D. Nos. Given in Tables 3
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 4. AIRPLANE NOISE LEVELS COMPARED TO FAA AND ICAO RECOMMENDATIONS.
(e) TAKEOFF (3 ENGINES) AT 3.5 NAUTICAL MILES (6,482 METERS).
-------
120
110
QD
T3
z
Q.
LLJ
LJU
>
LLJ
100
CO
CO
LLJ
U
cc
LLJ
Q.
LLJ
U-
U.
LLJ
90
80
70
1 I IT
93 69 FAR 36
h- 90 FAA WP/39
89 ICAO WP/64
I I I I
1 I
I IT
O16
15
O
I I I
I I I I
D. Nos. Given in Tables 3
J I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300 500
1000
FIGURE 4. AIRPLANE NOISE LEVELS COMPARED TO FAA AND ICAO RECOMMENDATIONS
(f) TAKEOFF (4 ENGINES) AT 3.5 NAUTICAL MILES (6,482 METERS).
-------
CD
T3
Q.
Ill
111
LU
C/5
O
z
Q
111
>
111
O
tr
LLI
a.
O
iii
LL
LL
Ill
120
110
100
90
80
70
98
1 1 1 1
- 102 " 69 FAR 36
FAA WP/39
& ICAO WP/64
1 1
©29
017
1
1
1
1 1 1 1
"
I.D. Nos. Given in Tables 3
0 2 Engines
CD 3 Engines
<£> 4 Engines
108 -
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 4. AIRPLANE NOISE LEVELS COMPARED TO FAA AND ICAO RECOMMENDATIONS.
(g) APPROACH (2, 3, and 4 ENGINES) AT 1.0 NAUTICAL MILE (1,852 METERS).
-------
120
cp
01
CD
T3
110
o
z
Q
LU
O
cc
LU
O.
O
LU
LU
I.D. Nos. Given in Table 4
O 2 Engines
(T) 3 Engines
4 Engines
70
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 5. NOISE LEVELS VS WEIGHT FOR CURRENT TECHNOLOGY EXISTING AIRPLANES.
(a) SIDELINE AT 0.25 NAUTICAL MILE (463 METERS).
-------
120
DQ
TJ
Q.
LLJ
LLJ
Q
111
>
LLJ
O
110
90
Q_
111
0
111
80
70
I I I I
93 69 FAR 36
80 Mean
77 Mean -3dB
1111
1 I
0
I
I
I I IT
I I 1 l
I I
I.D. Nos. Given in Table 4
0 2 Engines
(j] 3 Engines
<0> 4 Engines
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURES. NOISE LEVELS VS WEIGHT FOR CURRENT TECHNOLOGY EXISTING AIRPLANES.
(b) TAKEOFF AT 3.5 NAUTICAL Ml LES (6,482 METERS).
-------
120
m
TJ
a.
LU
LU
>
OT
O
O
QC
LU
a.
LU
O
110
100
- 102 69 FAR 36
I.D. Nos. Given in Table 4
Q 2 Engines
3 Engines
4 Engines
70
20 30 50 100
MAXIMUM AIRCRAFTWEIGHT, 1000 LB
200
300
500
1000
FIGURE 5. NOISE LEVELS VS WEIGHT FOR CURRENT TECHNOLOGY EXISTING AIRPLANES.
(c) APPROACH AT 1.0 NAUTICAL MILE (1,852 METERS).
-------
120
9
00
CO
•o
a.
ill
UJ
_l
UJ
O
Z
Q
UJ
>
UJ
o
tr
UJ
Q.
UJ
o
UJ
UJ
110
100
90
80
70
I I TT
>- 102 69 FAR 36
96 FAA WP/39 (3 & 4 Engines)
93 FAA WP/39 (2 Engines)
87 Mean
84 Mean -3dB
I I
I
I
I
Formulas Given in Table 2
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 6. COMPARISON OF FAA LEVELS WITH MEAN LEVELS OF CURRENT TECHNOLOGY AIRPLANES.
(a) SIDELINE.
-------
120
CD
CO
T3
Q.
Ul
>
ULJ
CO Z.
111
o
-------
120
m
1
Q.
110
100
cp
ro
o
Q
ill
O
-------
to
120
CO
T3
z
CL
110
CO
O
z
Q
LU
O
CC.
O
LLJ
LL
LL
111
100
90
80
70
I IT
^ 102 69 FAR 36
96 ICAO WP/64 (All Engines)
1 & FAAWP/39 (4 Engines)
87 Mean
84 Mean -3dB
1 I I
I I
I
I I
I I I I
I I
I I I I
108 -
Formulas Given in Table 2
I
I
1 1 I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 7. COMPARISON OF ICAO LEVELS WITH MEAN LEVELS OF CURRENT TECHNOLOGY AIRPLANES.
(a) SIDELINE.
-------
120
c
co
•o
a.
LU
a
in
>
LU
CJ
cc
LU
a.
LU
O
LU
LU
LL
LU
110
100
90
80
70
I I IT
93 69 FAR 36
89 ICAO WP/64
80 Mean
77 Mean -3dB
I i I 1
I I
I I I
I I
I I 1 l
I I
Formulas Given in Table 2
I
I I
L,
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 7. COMPARISON OF ICAO LEVELS WITH MEAN LEVELS OF CURRENT TECHNOLOGY AIRPLANES.
(b) TAKEOFF.
-------
120
cp
ro
m
-a
LU
>
UJ
t/5
O
z
Q
LU
O
-------
120
LU
W
O
LU
O
DC
LU
a.
LU
o
LU
LL
LL
LU
110
100
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 8. MODIFIED MEAN NOISE LEVELS FOR CURRENT TECHNOLOGY AIRPLANES.
* (a) SIDELINE.
-------
120
CO
(0
CD
T3
O.
Ill
111
_l
ID
C/5
O
O
111
O
tr
m
a.
O
LL
111
110
100
90
80
70
I I I
93
69 FAR 36
80
Modified
Mean
1111
I I IT
I
I
I I I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 8. MODIFIED MEAN NOISE LEVELS FOR CURRENT TECHNOLOGY AIRPLANES.
(b) TAKEOFF
-------
120
CO
t3
O.
01
O
z
Q
LLJ
O
oc
UJ
a.
in
O
LU
110
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
1000
FIGURE 8. MODIFIED MEAN NOISE LEVELS FOR CURRENT TECHNOLOGY AIRPLANES.
(c) APPROACH.
-------
120
cp
ro
m
•o
a.
LU
110
100
o
LU
>
111
CJ
cr
LU
o.
LU
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 9. MODIFIED MEAN -3dB NOISE LEVELS FOR AVAILABLE TECHNOLOGY AIRPLANES.
(a) SIDELINE.
-------
120
cp
ro
oo
m
Tl
0_
Ill
111
>
LLJ
o
z
Q
ill
O
IT
O
LU
LL.
LL
111
110
90
80
70
I I IT
93 69 FAR 36
77 Modified
Mean - 3dB
I I I I
I IT
I
I
_L
I I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 9. MODIFIED MEAN -3dB NOISE LEVELS FOR AVAILABLE TECHNOLOGY AIRPLANES.
» (b) TAKEOFF.
-------
120
CD
NJ
CO
CO
•a
a.
LU
LU
>
—
O
z
Q
ID
>
LU
O
cr
LU
a.
LU
CJ
LU
110
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 9. MODIFIED MEAN -3dB NOISE LEVELS FOR AVAILABLE TECHNOLOGY AIRPLANES.
(c) APPROACH.
-------
1000
500
m
_i
100
50
0)
c
E
'x
10
•10
1—I I I I 11
I I I I I I I I
T 1—i—rrrru
16
14
11
13
I.D. Nos. Given i,n Table 4
© 2 Engines
0 3 Engines
<£> 4 Engines
I I I
I I
50 100
Maximum Airplane Weight, 1000 LB
500
1000
FIGURE 10. PROPULSION VSWEIGHT FOR CURRENT TECHNOLOGY AIRPLANES.
(a) MAXIMUM THRUST.
9-30
-------
CO
CO
CO
a:
O)
-C
2.0
1.0
0.7
0.5
0.4
0.3
0.2
0.1
I 1 1 1
II
1 1 1 1
I
I I
I I 1 I
1 1 1
0 2 Engines
[•] 3 Engines
<£> 4 Engines
I.D. Nos. Given in Table 4
1 1 1 1
14 _
1 1 1 1
10 20 30 50 100
Maximum Aircraft Weight, 1000 LB
200
500 1000
FIGURE 10. PROPULSION VS WEIGHT FOR CURRENT TECHNOLOGY AIRPLANES.
(b) MAXIMUM THRUST/WEIGHT RATIO.
-------
120
CO
to
CO
TJ
Q.
LU
UJ
>
110
LU 100
o
2
Q
LU
HI
u
DC
LU
CL
LU
O
LU
U,
li.
LU
I.D. Nos. Given in Table 4
Q 2 Engines
0 3 Engines
4 Engines
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FI'GURE 11. NOISE LEVELS vs THRUST FOR CURRENT TECHNOLOGY AIRPLANES.
(a) SIDELINE.
-------
120
m
TJ
z
a.
110
CO
CO
CO
LU
o
IT
LU
0.
LU
LU
LL.
LL
LU
90
80
70
IT T I
04
I I I I
I
I I
I I IT
I 1 I I
I I
I I I
I.D. Nos. Given in Table 4
Q 2 Engines
Q 3 Engines
<> 4 Engines
I I
I ,
1 1 I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 11. NOISE LEVELS VS THRUST FOR CURRENT TECHNOLOGY AIRPLANES.
(b) TAKEOFF.
-------
120
00
•o
o_
110
100
<
o
2
a
HI
>
UJ
o
QC
UJ
a.
HI
O
UJ
UJ
I.D. Nos. Given in Table 4
0 2 Engines
Q] 3 Engines
4 Engines
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 11. NOISE LEVELS VS THRUST FOR CURRENT TECHNOLOGY AIRPLANES.
(c) APPROACH.
-------
70
O)
O
60 —
50
—
—
—
—
I 3
- 6
—
—
9
©2
© 1
© 4
0Q 5
Mv 7
8
—
16 ~
14<£o15-z
12^10 =
11EHD13
Sideline Z
59 (Mean)
Number of Engines
40
en
O CQ
Q.
LU
30
20
_
-
_
—
©4
o2 m
5f^o9
VC-"
08 ^,13
0 /^ 12rri H
3 °6 4z]
10
07
14
17 "I
OA ~
15 I
— .
•- "
Takeoff ^
32 (Mean)
Number of Engines
_ 70.
§"03
_1 "0
Q.
LU
60
4
©
©9
206
1 0
— U
- 3
11
H
10
16, 17
Approach
63 (Mean)
Number of Engines
FIGURE 12. NOISE LEVELS VS NUMBER OF ENGINES FOR
CURRENT TECHNOLOGY AIRPLANES.
(a) NORMALIZED FOR WEIGHT.
9-35
-------
70
01
O CD
z
Q_
LJJ
50
- 009
- 2
0 1
7 3
\- 6*5*8
40
D)
O CQ
30
20
70
S1
I CQ
60
4
0
©9
- 2©06
^- 3
10
11 EJEP 12
13
Number of Engines
Number of Engines
H
10
16 17 I
Sideline
63 (Mean)
_
•••
-
—
—
~
-
-
04
02
1 9
<*g
f®.
©
7
11
H
130
10
4/\
^ I
1^ vv — ^
-
,,^B-I
—
~—,
—
Takeoff _
33 (Mean)
15
Approach
67 (Mean)
Number of Engines
FIGURE 12. NOISE LEVELS VS NUMBER OF ENGINES FOR
CURRENT TECHNOLOGY AIRPLANES.
(b) NORMALIZED FOR THRUST.
9-36
-------
0.5
0.4
.c
01
0.3
0.2
5
©
3 6
© "
_ 8
— r^09
— ©
©
2
B
E
11
13
14 -
Number of Engines
FiriJRE 13 THRUST/WEIGHT RATIO VS NUMBER OF
FIGURE 13. THR TECHNOLOGY
AIRPLANES.
9-37
-------
120
f
CO
CO
CQ
Z
Q.
111
_J
UJ
to
O
z
Q
UJ
O
tr
LU
Q.
O
LU
UJ
110
100
(Airframe) Noise for Typical
Airplanes
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 14. NONPROPULSIVE APPROACH NOISE FOR TYPICAL AIRPLANES.
-------
to
CO
CO
120
CO
-a
LU
Q
LU
O
cc.
LU
Q.
LU
>
t-
CJ
111
LL
LL
UJ
110
90
8d
70
I I IT
102 69 FAR 36
84 Available
Mean—3dB
I 1 I I
I I
I I IT
Assumed 1500 FT
Distance
I
I I
I I I I
I r
Till
108 -
r
Estimated
600,000 Ib
Airplane
I
I I
I,
I i I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 15. NONPROPULSIVE NOISE FLOOR FOR AERODYNAMICALLY CLEAN AIRPLANES.
' (af SIDELINE. ' ' :
-------
120
CO
•o
a.
LU
UJ
>
o
z
cp Q
o >
LU
O
QC
LU
Q_
LU
>
O
111
110
100
90
80
70
1 I IT
93 69 FAR 36
77 Available
Mean—3dB
I I
I I
I I IT
Assumed 1000ft
Height
till
I I IT
108 -
Estimated
600,000 Ib
Airplane
1 I
I I 1 I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIQURE 15. NONPROPULSIVE NOISE FLOOR FOR AERODYNAMICALLY CLEAN AIRPLANES.
(b) TAKEOFF.
-------
120
111
10
a
LU
o
cc
LU
Q.
LU
o
LU
LL
LL
110
100
V
Estimated
600,000 Ib
Airplaine
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 15. NONPROPULSIVE NOISE FLOOR FOR AERODYNAMICALLY CLEAN AIRPLANES.
(c) APPROACH.
-------
120
-------
120
9
*»
CO
CO
,-o
Q.
LU
LU
>
Ul
C/J
O
Z
Q
LU
LU
O
QC
LU
CL
O
LU
LL.
110
100
90
80
70
I I IT
93 69 FAR 36
80 Mean
77 80 FAR 36
73 85 FAR 36
I I I 1
I I IT
1 j
Formulas Given in Table 2
10
20
30
50
100
200
300
500
1000
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
FIGURE 16. COMPLIANCE NOISE LEVELS FOR AVAILABLE AND FUTURE TECHNOLOGY AIRPLANES.
(b) TAKEOFF AT 3.5 NAUTICAL Ml LES (6,482 METERS).
-------
120
CD
•a
a.
m
110
uj 100
C/J
O
z
O
111
>
HI
O
cc.
LLI
a.
uu
O
LU
Formulas Given in Table 2
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
1000
FIGURE 16. COMPLIANCE NOISE LEVELS FOR AVAILABLE AND FUTURE TECHNOLOGY AIRPLANES.
(c) APPROACH AT 1.0 NAUTICAL MILE (1,852 METERS).
-------
120
<
m
•a
ID
>
Ol
UJ
to
Q
UJ
LU
-------
120
CD
T>
Q.
Ill
LU
LU
_l
CO
O
z
>
LU
O
cc.
LU
Q_
LU
O
LU
LL
110
100
Sideline & Approach
I
69 FAR 36 Range
Mean Range
(Current
Technology)
Card Study Range
(1981 Research Goal)
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 17. RANGE OF COMPLIANCE NOISE LEVELS FOR SIDELINE, TAKEOFF, AND APPROACH RECOMMENDED BY CARD STUDY:
(b) COMPARED WITH MEAN LEVELS OF 17 AIRPLANE SAMPLE.
-------
120
GO
T)
a.
01
110
111
u
cc
LiJ
o.
LLI
O
LU
Sideline & Approach
69 FAR 36
80 FAR 36 Range
(Available
Technology)
Card Study Range (1981 Research Goal)
80
70
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 17. RANGE OF COMPLIANCE NOISE LEVELS FOR SIDELINE, TAKEOFF, AND APPROACH RECOMMEtMDED BY CARD STUDY:
(c) COMPARED WITH 80 FAR 36.
-------
120
co
O_
LU
LLJ
>
110
LU 100
o
z
CO Q
-U LU
00 >
111
o
QC
111
Q.
UJ
>
o
LU
90
80
70
I I FT
1 I
X. Sideline & Approach
/
69 FAR 36 Range
I
Takeoff
85
73
85 FAR 36 Range
(Future
Technology)
I 1 I I
80
I 1 I I
I I
Card Study Range
(1981 Research Goal)
1 I
108 -
90 -
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200 300
500
1000
FIGURE 17. RANGE OF COMPLIANCE NOISE LEVELS FOR SIDELINE, TAKEOFF, AND APPROACH RECOMMENDED BY CARD STUDY:
(d) COMPAR ED WITH 85 FAR 36.
-------
120
CO
2
a.
111
>
110
s 10°
O
z
O
I.D. Nos. Given in Table 5
Q 2 Engines
3 Engines
4 Engines
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
FIGURE 18. PREDICTED NOISE LEVELS FOR MAJOR ACOUSTICAL CHANGE AIRPLANES.
(a) SIDELINE.
200 300
500
1000
-------
120
CD
a.
110
UJ
O
tr.
LLJ
a.
o
uj
UL
LL
UJ
100
90
80
70
93 69 FAR 36
80 Mean
I
I
I
I I IT
I
1 i
O2
3a
I.D. Nos. Given in Table 5
O 2 Engines
0 3 Engines
4 Engines
I
10
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
200
300
500
FIGURE 18. PREDICTED NOISE LEVELS FOR MAJOR ACOUSTICAL CHANGE AIRPLANES.
, (b) TAKEOFF.
1000
-------
120
-------
120
CO
•o
Q.
110
CO
o
z
co O
en i"
ro >
HI
O
-------
120
03
T3
O.
LU
LU
>
LU
HI
o
tr
m
o.
LU
>
o
110
I.D. Nos. Given in Table 6
O 2 Engines
3 Engines
4 Engines
70
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
FIGURE 19. PREDICTED NOISE LEVELS FOR NEW TYPE DESIGN AIRPLANES.
(b) TAKEOFF
200 300
500
1000
-------
120
CO
TJ
a.
LU
110
100
o
z
LLJ
O
DC
O
111
01
I.D. Nos. Given in Table 6.
0 2 Engines
3 Engines
4 Engines
20 30 50 100
MAXIMUM AIRCRAFT WEIGHT, 1000 LB
FIGURE 19. PREDICTED NOISE LEVELS FOR NEW TYPE DESIGN AIRPLANES.
(c) APPROACH.
200 300 500
1000
-------
50' & D50 For
Propeller—Driven
Airplanes
Flight Profile @ Takeoff
Tan a =
h-35
21266 - D35
R/C
Velocity
Vectors
@ Takeoff
sin a =
R/C
VY
HEIGHT
h = (21266- D35) Tan a + 35
CLOSEST POINT OF APPROACH (CPA)
d = h cos a = [ (21266 - D35) Tan a + 35
cos a
CLIMB CORRECTION REFERRED TO 1000 FT
C = 20 log
= 60 -20 log d
= 60 -20 log (21266-D35) sin a + 35 cos a
FOR SMALL a
C = 60-20 log T (21266 - D35) sin a + 35 1
FIGURE 20. CLIMB CORRECTION FOR HORIZONTAL FLIGHT PROCEDURE.
9-55
-------
25
30
Cumulative Noise Exposure, NEF, dB
35 40
45
30
25
I I I I
20
a
o
0)
o
t/t
c
~ 15
o
3
Q.
O
Q.
I I I I
I I I 1
Ldn
dB
60
65
70
75
80
National Average
•23 Airports
(63% National Average)
NEF
dB
25
30
35
40
45
Exposed
People
Millions
23
A/P
15.79
4.99
I.58
0.50
0.16
Nat.
AVE.
25.06
7.93
2.51
0.79
0.25
65
70 75
Cumulative Noise Exposure, Ldn, dB
80
50
I I I I
85
FIGURE 21. NUMBER OF PEOPLE IMPACTED BY AIRCRAFT NOISE: 1972 BASELINE.
9-56
-------
1
0
o
o
co"
i
i
t -c
r
1.0 NM
APR
S
3.5 NM
15,000 FT
-^ •-
S/L°
7/0 S/L
^ 3.5 NM _
T/0
APR
1.0 NM
NM
(a) Large Air-Carrier Airport
o
o
o
oo
1
t-<
r
^ 1.0 NM ^
^_ , ., , , ^
APR
s
2.0 NM
6,000 FT
S/L°
-j i 1
™
^
T/0 I
APR
2.0 NM
1.0 NM ^
0.25
NM
(b) General Aviation Airport
FIGURE 22. ONE-WAY RUNWAY AIRPORTS FOR INDICATORS OF NOISE IMPACT.
9-57
-------
NOISE EXPOSURE FORECAST, NEF, dB
15
20
25
30
35
40
45
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
Sideline
0.25 NM
From
Runway
Centerline
I 1 1 I
69 FAR 36
ICAO
FAA
Mean
Mod Mean
I i i i
1 i i i
I i i I
III'
I 1 1 1
1
1
1
1
Mean - 3dB
Mod Mean - 3dB
Future |
69 FAR 36
ICAO
1
FAA
Mean
1
Mod Mean |
Mean - 3 dB
Mod Mean - 3
Future
69 FAR 36
ICAO
dB
1
1
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3dB
Future |
i I i I
i i i 1
i i i I
i I i I
I 1 1 1
50
55
60 65
Day Night Level, Ldn, dB
70
75
80
Aircraft Mix A
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
140
89
81
30
34
46
o
o
o
w".
i 27,000 Ft.
4.5 NM *
1.0
NM
A.I
1 5,000
FT. *
1.0
I
£i
Total Ops = 2 x 420 = 840 Per Day (0700 - 2200)
0.25 NM
FIGURE 23. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE
AIR CARRIER AIRPORT: 840 OPERATIONS WITH VARIABLE PERCENT MIX.
(a) AIRCRAFT MIX A. (33.3% 4-ENGINE AIRCRAFT).
9-58
-------
15
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
20
NOISE EXPOSURE FORECAST, NEF, dB
25 30 35
40
45
Sideline
0.25 NM
From
Runway
Centerline
I'll
69 FAR 36
I i i i
I i i i
I i I I
1 i i i
I I i i
1
ICAO
FAA
Mean
Mod Mean
Mean - 3dB
Mod Mean - 3dB
Future
69 FAR 3fi
1
ICAO
FAA |
Mean
Mod Mean |
Mean - 3 dB
Mod Mean - 3
dB
1
Future
69 FAR 36
ICAO
1
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future I
i I i I
i i i 1
i i i I
i I i I
i I 1 1
1 1 I 1
50
55
60 65 70
Day Night Level, Ldn, dB
75
80
Aircraft Mix B
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
70
70
70
70
70
70
o
o
o
27,000 Ft.
4.5 NM *
1.0
NM
1 5,000
^ FT. *
1.0
NM
-©-
0.25 NM
Total Ops = 2 x420 = 840 Per Day (0700 - 2200)
FIGURE 23. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE
AIR CARRIER AIRPORT: 840 OPERATIONS WITH VARIABLE PERCENT MIX.
(b) AIRCRAFT MIX B. (16.7% 4-ENGINE AIRCRAFT).
9-59
-------
15
20
NOISE EXPOSURE FORECAST, NEF. dB
25 30 35
40
45
Sideline
0.25 NM
From
Runway
Center! ine
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
I 1 i 1
I 1 i i
1 i i i
I'll
I i i i
I I i i
69 FAR 36 I
ICAO 1
FAA
Mean
Mod Mean I
Mean-3dB 1
Mod Mean -3dB |
Future |
69 FAR 36 I
ICAO 1
FAA
Mean
Mod Mean |
Mean - 3 dB |
Mod Mean - 3 dB I
Future |
69 FAR 36 |
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future |
1 I I I
till
I I i I
i 1 i 1
I 1 1 1
50
55
60 65
Day Night Level, Ldn, dB
70
75
80
Aircraft Mix C
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
30
60
60
90
90
90
L. 27,000 Ft.
1.0
NM
4.5 NM
15,000
* FT. *
1.0
NM
I
0.25 NM
Total Ops = 2 x 420 = 840 Per Day (0700-2200)
FIGURE 23. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE
AIR CARRIER AIRPORT: 840 OPERATIONS WITH VARIABLE PERCENT MIX.
(c) AIRCRAFT MIX C. (7.14% 4-ENGINE AIRCRAFT).
9-60
-------
15
20
NOISE EXPOSURE FORECAST, NEF, dB
25 30 35
40
45
Sideline
0.25 NM
From
Runway
Centerline
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
i i i 1
i i i i
I 1 T 1
1 I 1 1
I 1 1 1
1 I 1 1
69 FAR 36 1
ICAO |
FAA |
Mean |
Mod Mean |
Mean - 3dB
Mod Mean - 3dB
Future |
69 FAR 3fi |
ICAO |
FAA |
Mean |
Mod Mean |
Mean - 3 dB
Mod Mean - 3 dB
Future |
69 FAR 36 I
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future |
i i i i
i i i I
1 1 1 1
1 1 1 1
till
50
55
60 65 70
Day Night Level, Ldn, dB
75
80
Aircraft Mix D
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/0
& App.
Ops/Day
20
40
60
80
100
120
27,000 Ft.
"" 4.5 NM "~
1.0
NM
A.I
15,000
* FT. *
1.0
NM
j
0.25 NM
Total Ops = 2 x 420 = 840 Per Day (0700 - 2200)
FIGURE 23. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE
AIR CARRIER AIRPORT: 840 OPERATIONS WITH VARIABLE PERCENTMIX.
(d) AIRCRAFT MIX D. (4.76% 4-ENGINE AIRCRAFT).
9-61
-------
15
NOISE EXPOSURE FORECAST, NEF.dB
20 25 30 35
40
45
0.25 MM
From
Runway
Centerline
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
lilt
I i i i
liii
I'll
I i i i
I i i i
69 FAR 36 ]
ICAO I
FAA I
Mean I
Mod Mean I
Mean - 3dB
Mod Mean -3dB
Future |
69 FAR 36 I
ICAO I
FAA I
Mean |
Mod Mean I
Mean - 3 dB
Mod Mean - 3 dB
Future |
69 FAR 36 |
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future |
till
i i i I
i i i I
i I I I
1 1 I 1
50
55
60 65 70
Day Night Level, Ldn, dB
75
80
Aircraft Mix E
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
0
50
65
85
100
120
1H
1.0
-------
15
Takeoff
3.5 NM
From
Brake
Release
NOISE EXPOSURE FORECAST, NEF, dB
20 25 30 35
Sideline
0.25NM
From
Runway
Centerline
Approach
1.0 NM
From
Runway
Threshold
50
55
40
45
I 1 1 I
69 FAR 36
i i i i
I i i i
I i i I
I i i '
1 i i i
ICAO |
FAA |
Mean 1
Mod Mean |
Mean - 3dB
Mod Mean - 3dB
Future
69 FAR 3R
ICAO
FAA
Mean
Mod Mean
1
Mean - 3 dB
Mod Mean - 3
dB
Future |
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future
i 1 I 1
i i i 1
1
i i i 1
i I i I
i I I 1
1 1 I 1
60 65
Day Night Level, Ldn, dB
70
75
80
Aircraft Mix F
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
147
93
85
32
36
48
IN
i
1.0
NM
^
J
27,000 Ft. _
4.5 NM
1 5,000
* FT. *
1.0
NM
I k v
\_JI —
V
0.25 NM
Total Ops = 2 x 441 = 882 Per Day (0700 - 2200)
FIGURE 24. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE AIR
CARRIER AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(a) 882 OPERATIONS.
9-63
-------
10
NOISE EXPOSURE FORECAST, NEF, dB
15 20 25 30
35
40
Sideline
0.25 NM
From
Runway
Centerline
Takeoff <
3.5NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
i i i 1
Jiii
1 i i i
I'll
I i i i
I i 1 1
69 FAR 36
ICAO 1
FAA 1
Mean I
Mod Mean |
Mean - 3dB
Mod Mean -3dB
Future 1
69 FAR 3fi I
ICAO
FAA
Mean |
Mod Mean I
Mean - 3 dB
Mod Mean - 3 dB
Future |
-
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future |
I I I I
i i i I
i i i I
i i i I
1 1 I 1
45
50
55 60 65
Day Night Level, Ldn, dB
70
75
Aircraft Mix G
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
46
30
27
10
12
15
i 27,000 Ft.
4.5 NM *
1.0
15,000
FT. *
1.0
NM
V-
'0.25 NM
Total Ops = 2 x 140 = 280 Per Day (0700 - 2200)
FIGURE 24. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE AIR
CARRIER AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX
(b) 280 OPERATIONS.
9-64
-------
Sideline
0.25 NM
From
Runway
Centerline
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
10
NOISE EXPOSURE FORECAST, NEF, dB
15 20 25
30
35
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3dB
Mod Mean - 3dB
Future
69 FAR 3fi
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean - 3 dB
Future
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3dB
Future
I I
I I 1 1
40
45
50 55
Day Night Level, Ldn, dB
60
65
70
Aircraft Mix H
.No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
14
9
9
3
4
5
_ 27,000 Ft. _
1.0
NM
4.5 NM
15,000
* FT. *
1.0
NM
-©-
0.25 NM
Total Ops = 2 x 44 = 88 Per Day (0700 - 2200)
FIGURE 24. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE AIR
CARRIER AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(c) 88 OPERATIONS.
9-65
-------
NOISE EXPOSURE FORECAST, NEF, dB
10 15 20
25
30
Sideline
0.25 NM
From
Runway
Centerline
Takeoff
3.5 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
i I i 1
I i i i
I i i i
i i i i
l i i i
l i i i
69 FAR 36
ICAO
FAA 1
Mean |
Mod Mean I
Mean- 3dB
Mod Mean - 3dB
Future I
69 FAR 3fi |
ICAO
FAA
Mean |
Mod Mean |
Mean - 3dB
Mod Mean - 3 dB
Future |
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future
i I i i
i i i 1
i i i I
i i i I
i 1 1 1
1 1 l 1
35
40
45 50
Day Night Level, Ldn, dB
55
60
65
Aircraft Mix 1
No.
Eng.
4
3
3
2
2
2
Max.
Wt.
KLB
800
500
200
300
150
25
No. T/O
& App.
Ops/Day
4
3
3
1
1
2
IN
1.0
NM
k
J
27,000 Ft.
4.5 NM
15,000
FT. *
-
1.0
/-
^
0.25 NM
Total Ops = 2 x 14 = 28 Per Day (0700 - 2200)
FIGURE 24. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR LARGE AIR
CARRIER AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(d) 28 OPERATIONS.
9-66
-------
10
Takeoff
2.0 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
15
NOISE EXPOSURE FORECAST, NEF, dB
20 25 30
35
40
Sideline
0.25 NM
From
Runway
Centerline
1 1 1 I
69 FAR 36
ICAO
I i i i
I i i i
I i i I
1 i i i
ill)
1
FAA |
Mean
Mod Mean
Mean - 3dB
Mod Mean - 3dB
Future |
69 FAR 3fi |
ICAO
FAA
1
Mean [
Mod Mean |
Mean - 3dB
Mod Mean - 3
dB
Future |
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3dB
Future |
i i i I
i I i I
i I 1 1
1 1 1
45
50
55 60 65
Day Night Level, Ldn, dB
70
75
Aircraft Mix A
.No.
Eng.
2
2
2
4
2
Max.
Wt.
KLB
15
20
25
45
60
No. T/O
& App.
Ops/Day
118
115
94
42
31
i 18,000 Ft.
"* 3.0NM *~
1.0
NM
6,000
* FT. *
1.0
I
-<•>•
0.25 NM
Total Ops = 2 x400 =800 Per Day (0700 - 2200)
FIGURE 25. CUMULATIVE NOISE EXPOSURE ATONE-WAY RUNWAY FOR GENERAL
AVIATION AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(a) 800 OPERATIONS.
9-67
-------
10
NOISE EXPOSURE FORECAST, NEF, dB
15 20 25
30
35
Sideline
0.25 NM
From
Runway
Centerline
Takeoff
2.0 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
i i i 1
i i i i
i i i i
I i i I
I i i i
i i i i
69 FAR 36
ICAO |
FAA
Mean
Mod Mean
Mean -3dB
Mod Mean -3dB
Future
69 FAR 3fi J
ICAO I
FAA 1
Mean |
Mod Mean |
Mean - 3 dB
Mod Mean - 3 dB
Future |
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3dB
Future |
ill!
i i i I
i i i i
i i i I
till
40
45
50 55 60
Day Night Level, Ldn, dB
65
70
Aircraft Mix B
.No.
Eng.
2
2
2
4
2
Max.
Wt.
KLB
15
20
25
45
60
No. T/O
& App.
Ops/Day
37.0
37.0
30.0
13.0
10.0
4 18'
1.0
NM
3
000 Ft.
.ONM
6,000
FT. *
1.0
NM
0.25 NM
Total Ops = 2 x 127 = 254 Per Day (0700 - 2200)
FIGURE 25. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR GENERAL
AVIATION AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(b) 254 OPERATIONS.
9-68
-------
Sideline
0.25 NM
From
Runway
Centerline
Takeoff
2.0 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
NOISE EXPOSURE FORECAST, NEF, dB
10 15 20
25
30
r I I I
i i i i
I i i i
I'll
I'll
III!
69 FAR 36
ICAO |
FAA |
Mean
Mod Mean
Mean - 3dB
Mod Mean - 3dB
Future |
69 FAR 3R |
ICAO |
FAA |
Mean |
Mod Mean |
Mean - 3 dB
Mod Mean - 3 dB
Future |
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future |
i I I I
i i i 1
i I i I
i 1 1 1
1 1 1 1
35
40
45 50
Day Night Level, Ldn, dB
55
60
65
Aircraft Mix C
No.
Eng.
2
2
2
4
2
Max.
Wt.
KLB
15
20
25
45
60
No. T/O
& App.
Ops/Day
12.0
12.0
9.0
4.0
3.0
H
i 18,000 Ft.
* 3.0NM
1 .0 6,000
NM FT.
a— • ,
^ r*
1.0
) •
"0.25 NM
Total Ops = 2 x40.0 = 80 Per Day (0700 - 2200)
FIGURE 25. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR GENERAL
AVIATION AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(c) 80 OPERATIONS.
9-69
-------
-5
NOISE EXPOSURE FORECAST, NEF, dB
5 10 15
20
25
Sideline
0.25 NM
From
Runway
Center! ine
Takeoff
2.0 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
I ! 1 1
I i i i
I i i i
I i i I
1 i i i
I i i i
69 FAR 36
ICAO 1
FAA
Mean
Mod Mean
Mean - 3dB
Mod Mean - 3dB
Future |
69 FAR 3fi |
ICAO I
FAA |
Mean |
Mod Mean |
Mean - 3 dB
Mod Mean - 3 dB
Future |
69 FAR 36
ICAO
FAA |
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3dB
Future |
i I I I
i i i I
i i i i
i I i I
1 1 I 1
30
35
40 45 50
Day Night Level, Ldn, dB
55
60
Aircraft Mix D
.No.
Eng.
2
2
2
4
2
Max.
Wt.
KLB
15
20
25
45
60
No. T/O
& App.
Ops/Day
4.0
4.0
3.0
I.O
I.O
18
1.0
NM
3
,000 Ft. _
.ONM
6,000
"*" FT. "
1.0
NM
0.25 NM
Total Ops = 2 x I3.0 = 26 Per Day (0700 - 2200)
FIGURE 25. CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR GENERAL
AVIATION AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(d) 26 OPERATIONS.
9-70
-------
-10
-5
NOISE EXPOSURE FORECAST, NEF, dB
0 5 10
15
20
Sideline
0.25 NM
From
Runway
Centerline
Takeoff
2.0 NM
From
Brake
Release
Approach
1.0 NM
From
Runway
Threshold
i i i 1
I i i i
I i i I
I i i i
I i i i
69 FAR 36
ICAO |
FAA |
Mean
Mod Mean
Mean - 3dB
Mod Mean - 3dB
Future
69 FAR 3fi J
ICAO |
FAA |
Mean |
Mod Mean |
Mean - 3 dB
Mod Mean - 3 dB
Future
69 FAR 36
ICAO
FAA
Mean
Mod Mean
Mean - 3 dB
Mod Mean -3 dB
Future |
i'''
i i i I
i i i I
i i i I
1 1 1 1
I i 1
25
30
35 40 45
Day Night Level, Ldn, dB
50
55
Aircraft Mix E
.No.
Eng.
2
2
2
4
2
Max.
Wt.
KLB
15
20
25
45
60
No. T/O
& App.
Ops/Day
1.2
1.2
0.9
0.4
0.3
1H-J
,u. v
18,000 Ft.
~~ 3.0 NM
1.0 6,000
NM FT.
a— 1
1.0
NM
fj
^
^
0.25 NM
Total Ops = 2 x 4.0 = 8 Per Day (0700 - 2200)
FIGURE 25 CUMULATIVE NOISE EXPOSURE AT ONE-WAY RUNWAY FOR GENERAL
AVIATION AIRPORT: VARIABLE OPERATIONS WITH CONSTANT PERCENT MIX.
(e) 8 OPERATIONS.
9-71
-------
APPENDIX, SECTION, AND TITLE
FAR 36
A36. 1. Noise Certification Test
and Measurement Conditions
A36.2. Measurement of Aircraft
Noise Received on the Ground
A36. 3. Reporting and Correcting
Measured Data
A36.4. Symbols and Units
A36. 5. Atmospheric Attenuation
of Sound
A36.6. Detailed Correction
Procedures
B36.1. General
B36.2. Perceived Noise Level
B36. 3. Correction for Spectral
Irregularities
B36.4. Maximum Tone Corrected
Perceived Noise Level
B36.5. Duration Correction
B36. 6. Effective Perceived Noise
Level
B36. 7. Mathematical Formulation
of the Noy Table
C36.1. Noise Measurement and
Evaluation
C36. 3. Noise Measuring Points
C36. 5. Noise Levels
C36. 7. Takeoff Test Conditions
C36. 9. Approach Test Conditions
CAN/4 - WP/20
CI2. Noise Certification Test
and Measurement Conditions
CIS. Measurement of Aeroplane
Noise Received on the Ground
CIS. Reporting of Data to the
Certificating Authorities and
Correcting Measured Data
CI6. Nomenclature
CIS. Sound Attenuation in Air
CI9. Flight Test Results
Transposition Methods
CI4. Calculation of Effective
Perceived Noise Level from
Measured Noise Data
CI4. Ditto
CI4. Ditto
CI4. Ditto
CI4. Ditto
CI4. Ditto
CI7. Mathematical Formulation
of the Noy Table
C2.2. Noise Certification
Reference Procedures
C2.4. Noise Measurements
C2. 5. Maximum Noise Levels
C2.2. Noise Certification
Reference Procedures
C2.2. Ditto
TABLE 1. COMPARISON BETWEEN TECHNICAL STANDARDS OF FAR 36
AND ICAO CAN/4-WP/20
10-1
-------
General Formula: EPNL = A LOG(W) + B
Case
69 FAR 36
FAA
WP/39
ICAO
WP/64
Mean of
17 Airplane
Sample
80 FAR 36
Available
Technology
85 FAR 36
Future
Technology
Meas.
Point
S/L
T/0
APP
S/L
T/0
APP
S/L
T/0
APP
S/L
T/0
APP
S/L
T/0
APP
S/L
T/0
APP
No. of
Engines
ALL
2
3
4
2
3
4
All
All
All
All
All
Constants, dB
A
6.644
16.610
6.644
6.644
13.288
6.644
6.644
16.610
6.644
7.000
12.000
7.000
7.000
12.000
7.000
7.000
12.000
7.000
B
69.611
12.027
69.611
60.611
60.611
63.611
21.222
24.222
27.222
65.611
63.611
8.027
65.611
59.000
32.000
63.000
56.000
29.000
60.000
51.000
25.000
57.000
Limits
Lower
W
1000lb.
75
75
212
75
89
89
53
75
75
10
10
10
EPNL
EPNdB
102
93
102
93
96
96
87
90
90
98
96
89
98
87
80
91
84
77
88
79
73
85
Upper
W
1000 Ib
600
850
850
850
850
800
850
1000
1000
•
1000
EPNL
EPNdB
108
100
100
103
100
103
106
105
103
106
105
101
104
105
98
101
102
93
97
99
Slope
dB Per
W/2
- 2.000
5.000
- 2.000
9 nnn
4 flOfl
-2.000
- 2.000
- 5.000
-2.000
-2.107
-3.612
-2.107
-2.107
-3.612
-2.107
-2.107
-3.612
-2.107
TABLE 2. FORMULAS FOR COMPLIANCE NOISE LEVEL CURVES.
-------
I.D.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Airplane
Type
DC-9-30
DC-9-30
DC-9-30
DC-9-30
DC-9-30
DC-9-30
DC-9-30
DC-9-30
DC-9-30
DC-9-40
DC-9-40
DC-9-40
DC-9-40
B-737-200-QN
B-737-200-QN
B-737-200-QN
CESSNA 500
SABRE-NA265-60
SABRE-NA265-80
Engine
No.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Type
JT8D-7A
JT8D-7A
JT8D-9
JT8D-9
JT8D-9
JT8D-15
JT8D-15
JT8D-15
JT8D-15
JT8D-11
JT8D-11
JT8D-15
JT8D-15
JT8D-15
JT8D-9
JT8D-17
JT15D-1
JT12A-8
CF700-2D-2
Max.
Wt.
W
KLB
108.0
94.0
110.0
108.0
103.0
114.0
110.0
108.0
98.0
114.0
107.0
114.0
105.0
115.5
115.5
117.0
11.5
20.0
23.3
Max. Thrust
Per
Eng.
KLB
14.0
14.0
14.5
14.5
14.5
15.5
15.5
15.5
15.5
15.0
15.0
15.5
15.5
15.5
14.5
16.0
2.2
3.3
4.32
Tot.
T
KLB
28.0
28.0
29.0
29.0
29.0
31.0
31.0
31.0
31.0
30.0
30.0
31.0
31.0
31.0
29.0
32.0
4.4
6.6
8.63
T/W
0.259
0.298
0.264
0.269
0.282
0.272
0.282
0.287
0.316
0.263
0.280
0.272
0.295
0.268
0.251
0.274
0.383
0.330
0.370
Noise Level, EPNdB
S/L
@0.25
NMr
97.3
97.8
98.8
98.8
99.0
100.5
100.6
100.7
101.1
99.9
99.6
100.5
100.8
103.2
100.6
104.4
86.1
100.3
91.3
T/0 @3.5 NM
With
C/B
95.1
91.7
96.1
95.5
94.3
95.8
94.7
94.2
91.2
96.8
95.2
95.8
93.3
94.8
95.4
94.0
_
No
C/B
—
_
—
_
_
_
—
_
77.7
95.0
90.7
App
@ 1.0
NM
97.3
97.0
99.1
99.0
_
99.0
98.8
98.4
99.4
_
99.4
__
103.8
103.8
104.4
87.7
98.5
100.2
Notes &
Source of
Data
(1) FAA
(1) FAA
(1) FAA
(1) FAA
FAA
(1) FAA
(1) FAA
(1) FAA
FAA
(1) FAA
FAA
(1) FAA
FAA
(2) FAA
(2) FAA
FAA
(3) FAA
(4) FAA
(5) FAA
o
CO
Approach Flaps: (1) 50°, (2) 30°, (3)40°, (4)23.5°, (5)25°
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(a) 2 ENGINES
-------
I.D.
No.
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
Airplane
Type
Learjet-35/36
Learjet-24D
Leariet-24 Mod
Learjet-24 Mod
Learjet-25 B, C
Learjet-25 Mod
Learjet-25 Mod
Falcon-10
Airbus-300B
Corvette-SN-601
F28-Mk1000
F28-Mk2000
HS-748-2A
BAC-1 11-200
Gulfstream II
HS- 125-400
VFW-614
Caravelle 10
B-737-200
B-737-200
Engine
No.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Type
TFE 731-2
CJ610-6
GJ610-6
CJ610-6
CJ610-6
CJ610-6
CJ610-6
TFE 731-2
CF6-50A
JT15D-4
Spey 555-15
Spey 555-15
Dart Mk 532-2 L
Spev512-14DW
Spev511-8
Viper 522
SNECMAM45-01
JT8D-7
JT8D-9
JT8D-9
Max.
Wt.
W
KLB
17.0
13.5
13.5
13.5
15.0
15.0
15.0
18.3
302.0
13.89
65.0
65.0
46.5
80.0
62.0
23.3
44.0
64.3
103.5
103.5
Max. Thrust
Per
Eng.
KLB
3.5
2.95
2.95
2.95
2.95
2.95
2.95
3.5
49.0
2.5
9.85
9.85
TURBO
12.55
11.8
3.36
7.6
14.0
14.5
14.5
Tot.
T
KLB
7.0
5.9
5.9
5.9
5.9
5.9
5.9
7.0
98.0
5.0
19.7
19.7
PROP
25.10
23.6
6.72
15.2
28.0
29.0
29.0
T/W
0.412
0.437
0.437
0.437
0.393
0.393
0.393
0.383
0.325
0.360
0.303
0.303
—
0.314
0.381
0.288
0.345
0.435
0.280
0.280
Noise Level, EPNdB
S/L
@0.25
NM
86.7
97.3
99.3
99.3
97.1
99.3
99.3
86.4
95.3
85.4
99.5
99.5
96.3
101.3
102.7
99.0
92.0
101.0
100.9
100.9
T/0 @ 3.5 NM
With
C/B
_
—
—
—
—
79.6
90.2
_
90.0
90.0
92.5
90.9
90.0
90.0
99.5
91.3
91.3
No
C/B
83.4
90.1
91.8
91.8
91.3
94.0
94.0
82.9
—
80.4
—
_
95.0
_
—
—
—
_
App
@ 1.0
NM
92.2
99.1
100.7
101.7
99.6
100.8
102.7
95.3
101.3
89.5
101.2
101.8
103.8
100.3
98.2
104.0
97.0
106.0
111.5
107.1
Notes &
Source of
Data
(1) FAA
(1) FAA
(1) FAA
(1) FAA
(1) FAA
(1) FAA
(1) FAA
(2) FAA
(3) FAA
(4) FAA
(5) FAA
(5) FAA
(6) FAA
(7) FAA
(8) FAA
Rolls-Royce
Fokker
Rolls-Royce
(1) Boeing
(2) Boeing
Approach Flaps: (1) 40°, (2) 52°, (3) 20° Slats, (4) 35°, (5) 42°, (6) 27.5°, (7) 45°, (8) 39°.
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES
(b) 2 ENGINES (CONTINUED)
-------
I.D.
No.
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Airplane
Type
B-737-200-QN
B-737-200-QN
B-737-200 Adv
B-737-200Adv
B-737-200 Adv-QN
B-737-200 Adv-QN
DC-9-30
DC-9-30-QN
DC-9-30
DC-9-30-QN
DC-9-50-QN
A-300B
A-300B
BAC-1 11-500
Gulfstream 2
Falcon 20
HS-125-601
Westwind 1121
Westwind 1123
F28Mk 6000
F28-Mk 6000
Engine
No.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Type
JT8D-9
JT8D-9
J.T8D-9
JT8D-9
JT8D-9
JT8D-9
JT8D-9
JT8D-9
JT8D-11
JT8D-11
JT8D-15
CF6-50A
CF6-50A
Spey 512-14DW
Spev 512-8
CF 700-2D
Viper 601
CJ610-9
CJ610-9
Spey 555-1 5H
Spey 555-1 5H
Max.
Wt.
W
KLB
103.5
103.5
115.5
115.5
115.5
115.5
108.0
108.0
114.0
114.0
120.0
302.1
302.1
100.0
62.0
27.3
25.2
18.5
20.5
73.0
70.8
Max. Thrust
Per
Eng.
KLB
14.5
14.5
14.5
14.5
14.5
14.5
14.5
14.5
15.0
15.0
15.5
51.0
51.0
12.55
11.4
4.25
3.75
3.1
3.1
9.85
9.85
Tot.
T
KLB
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
30.0
30.0
31.0
102.0
102.0
25.1
22.8
8.5
7.5
6.2
6.2
19.70
19.70
T/W
0.280
0.280
0.251
0.251
0.251
0.251
0.269
0.269
0.263
0.263
0.258
0.338
0.338
0.251
0.368
0.311
0.298
0.335
0.302
0.270
0.278
Noise Level, EPNdB
S/L
@0.25
NM
100.9
100.9
100.6
100.6
100.6
100.6
99.0
99.0
100.0
100.0
101.0
95.0
95.0
108.5
108.0
91.0
104.5
104.0
106.0
93.3
98.6
T/O @3.5 NM
With
C/B
91.3
91.3
95.3
95.3
95.3
95.3
96.0
96.0
97.0
97.0
97.0
90.0
90.0
103.0
94.5
—
-
99.5
93.3
92.4
No
C/B
_
—
101.7
101.7
101.7
101.7
_
_
_
—
_
92.0
92.0
102.5
91.0
97.5
101.5
—
—
_
App
@ 1.0
NM
104.9
100.8
111.7
107.7
105.1
101.1
105.0
99.0
105.0
99.0
100.0
102.0
101.0
102.5
99.5
102.0
102.0
107.0
106.0
98.0
96.6
Notes &
Source of
Data
(1) Boeing
(2) Boeing
(1) Boeing
(2) Boeing
(1) Boeing
(2) Boeing
(3) Boeing
(3) Boeing
(3) Boeing
(3) Boeing
(3) Boeing
(4) Boeing
(5) Boeing
EPA
EPA
EPA
EPA
EPA
EPA
Fokker
Fokker
p
61
Approach Flaps: (1) 40°, (2) 30°, (3) 50°, (4) 25°, (5) 15°
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(c) 2 ENGINES (CONCLUDED)
-------
I.D.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Airplane
Type
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC-10-10
DC- 10-30
DC-10-30
DC-10-30
DC-10-30
DC-10-30
DC-10-30
DC-10-30
DC-10-30
Engine
No.
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Type
CF6-6D
CF6-6D
CF6-6D
CF6-6D
CF6-6D
CF6-6D
CF6-6D
CF6-6D1
CF6-6D1
CF6-6D1
CF6-6D1
CF6-6D1
CF6-6D1
CF6-50A
CF6-50A
CF6-50A
CF6-50A
CF6-50C
CF6-50C
CF6-50C
CF6-50C
Max.
Wt.
W
KLB
440.0
440.0
430.0
430.0
410.0
410.0
377.5
440.0
440.0
430.0
430.0
386.5
386.5
550.0
550.0
519.6
519.6
565.0
555.0
534.4
440.0
Max. Thrust
Per
Eng.
KLB
39.3
39.3
39.3
39.3
39.3
39.3
39.3
40.3
40.3
40.3
40.3
40.3
40.3
48.4
48.4
48.4
48.4
51.0
51.0
51.0
51.0
Tot.
T
KLB
117.9
117.9
117.9
117.9
117.9
117.9
117.9
120.9
120.9
120.9
120.9
120.9
120.9
145.2
145.2
145.2
145.2
153.0
153.0
153.0
153.0
T/W
0.268
0.268
0.274
0.274
0.288
0.288
0.312
0.275
0.275
0.281
0.281
0.313
0.313
0.264
0.264
0.279
0.279
0.271
0.276
0.287
0.348
Noise Level, EPNdB
S/L
@0.25
NM
95.1
95.1
95.2
95.2
95.6
95.6
95.8
95.4
95.4
95.6
95.6
96.0
96.0
95.7
95.7
96.0
96.0
97.3
97.3
97.6
98.5
T/0@3.5NM
With
C/B
—
—
—
—
—
-
-
—
—
_
—
—
_
—
—
—
—
—
_
_
No
C/B
99.0
99.0
98.2
98.2
96.8
96.8
94.6
98.2
98.2
97.4
97.4
94.6
94.6
103.7
103.7
102.1
102.1
104.4
104.0
103.2
100.2
App
@ 1.0
NM
100.3
105.4
99.7
104.7
99.2
104.2
—
100.3
105.4
99.7
104.7
99.2
104.2
103.0
108.4
102.6
108.2
108.4
103.0
108.2
102.6
Notes &
Source of
Data
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(1) FAA
(2) FAA
FAA
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(2) FAA
(1) FAA
(2) FAA
(1) FAA
o
0)
(1) 35-Deg. App. Flaps: (2) 50-Deg. App. Flaps:
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(d) 3 ENGINES
-------
I.D.
No.
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Airplane
Type
DC- 10-40
DC- 10-40
DC- 10-40
DC- 10-40
DC- 10-40
DC- 10-40
L-1011-1
L-1011-1
L-1011-1
L-1011-1
L-1011-1
L-1011-1
B-727-200-QN
B-727-200-QN
L-1011-1
L-1011-1
L-1011-1
L-1011-100
L-1011-100
Engine
No.
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Type
JT9D-20
JT9D-20
JT9D-20
JT9D-20
JT9D-20
JT9D-20
RB211-22C
RB211-22C
RB211-22C
RB211-22C
RB211-22C
RB211-22C
JT8D-15
JT8D-15
RB211-22B
RB211-22B
RB211-22B
RB211-22B
RB211-22B
Max.
Wt.
W
KLB
530.0
530.0
484.0
484.0
430.0
430.0
430.0
416.0
416.0
430.0
422.0
396.0
190.5
175.0
430.0
403.0
403.0
466.0
450.0
Max. Thrust
Per
Eng.
KLB
49.4
49.4
49.4
49.4
49.4
49.4
42.0
42.0
42.0
42.0
42.0
42.0
15.5
15.5
42.0
42.0
42.0
42.0
42.0
Tot.
T
KLB
148.2
148.2
148.2
148.2
148.2
148.2
126.0
126.0
126.0
126.0
126.0
126.0
46.5
46.5
126.0
126.0
126.0
126.0
126.0
T/W
0.280
0.280
0.306
0.306
0.345
0.345
0.293
0.303
0.303
0.293
0.299
0.318
0.244
0.266
0.293
0.313
0.313
0.270
0.280
Noise Level, EPNdB
S/L
@0.25
NM
94.3
94.3
94.3
94.3
94.3
94.3
95.0
95.1
95.1
95.2
95.0
95.2
102.2
102.3
95.0
95.1
95.1
94.8
94.9
T/0 @ 3.5 NM
With
' C/B
—
—
—
_
—
_
—
—
—
100.0
97.0
—
_
—
_
No
C/B
100.7
100.7
98.4
98.4
95.8
95.8
97.0
96.1
96.1
97.9
97.7
96.0
_
96.0
94.1
94.1
98.5
97.4
App
@ 1.0
NM
100.4
105.4
99.2
104.6
98.5
103.8
103.4
102.1
101.5
103.4
102.1
101.5
101.0
103.2
102.8
101.8
101.2
102.8
101.9
Notes &
Source of
Data
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(1) FAA
(2) FAA
(4) FAA
(3) FAA
(3) FAA
(4) FAA
(3) FAA
(3) FAA
(5) FAA
(6) FAA
(4) FAA
(3) FAA
(3) FAA
(4) FAA
(3) FAA
(1) 35-Deg. App. Flaps:
(2) 50-Deg. App. Flaps:
(3) 33-Deg. App. Flaps:
(4) 42-Deg. App. Flaps:
(5) 30-Deg. App. Flaps:
(6) 40-Deg. App. Flaps:
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(e) 3 ENGINES (CONTINUED)
-------
I.D.
No.
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
Airplane
Type
B-727-200
B-727-200
B-727-200-QN
B-727-200-QN
B-727-200-Adv-QN
B-727-200-Adv-QN
DC-10-10
DC-10-10
DC- 10- 30
DC- 10-30
DC- 10-40
DC-10-40
L-1011-1
L-1011-1
L-1011-100
Falcon 50
Trident 3B
Engine
No.
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Type
JT8D-9
JT8D-9
JT8D-9
JT8D-9
JT8D-15
JT8D-15
CF6-6D1
CF6-6D1
CF6-50A
CF6-50A
JT9D-20 Dry
JT9D-20 Dry
RB211-22C
RB211-22C
RB211-22B
TFE 731-3
Spey 512
Max.
Wt.
W
KLB
172.5
172.5
172.5
172.5
190.5
190.5
440.0
440.0
555.0
555.0
530.0
530.0
430.0
430.0
450.0
36.6
158.8
Max. Thrust
Per
Eng.
KLB
14.5
14.5
14.5
14.5
15.5
15.5
41.0
41.0
49.0
49.0
49.4
49.4
42.0
42.0
42.0
3.7
12.0
Tot.
T
KLB
43.5
43.5
43.5
43.5
46.5
46.5
123.0
123.0
147.0
147.0
148.2
148.2
126.0
126.0
126.0
11.1
36.0
T/W
0.252
0.252
0.252
0.252
0.244
0.244
0.280
0.280
0.264
0.264
0.280
0.280
0.293
0.293
0.280
0.303
0.227
Noise Level, EPNdB
S/L
@0.25
NM
100.4
99.9
100.4
99.9
102.2
102.2
96.0
96.0
96.0
96.0
95.0
95.0
95.0
95.0
94.9
94.0
105.5
T/0 @ 3.5 NM
With
C/B
101.2
100.0
99.0
97.5
100.0
100.0
_
—
—
—
_
—
_
—
87.0
104.5
No
C/B
107.8
107.4
107.0
106.6
109.8
109.8
99.0
99.0
104.0
104.0
101.0
101.0
97.0
97.0
97.4
—
—
App
@ 1.0
NM
108.2
109.5
100.4
103.2
100.4
103.2
106.0
102.0
108.0
103.0
105.0
101.0
103.0
102.0
101.5
97.0
110.0
Notes &
Source of
Data
(1) Boeing
(2) Boeing
(1) Boeing
(2) Boeing
(3) Boeing
(2) Boeing
(4) Boeing
(5) Boeing
(4) Boeing
(5) Boeing
(4) Boeing
(5) Boeing
(6) Boeing
(7) Boeing
(7) Lockheed
AW&ST
Rolls-Royce
o
do
(1) 30-Deg. App. Flaps & 15 Deg. T/0 Flaps
(2) 40-Deg. App. Flaps & 15 Deg. T/0 Flaps
(3) 30-Deg. App. Flaps & 5 Deg. T/0 Flaps
(4) 50-Deg. App. Flaps
(5) 35-Deg. App. Flaps
(6) 42-Deg. App. Flaps
(7) 33-Deg. App. Flaps
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(f) 3 ENGINES (CONCLUDED)
-------
I.D.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Airplane
Type
B-747-100
B-747-100
B-747-100A
B-747-100A
B-747-100C
B-747-100C
B-747-100C
B-747-200B
B-747-200 B, C, F
B-747-200 B, C, F
B-747-200 B,C,F
B-747-200 B, C, F
B-747-200 B, C, F
L-382EIG
Jetstar 2
Jetstar Dash 8
DC-8-61
Concorde
TU-144
Comet 4
Convair 880
Convair 990
Engine
No.
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Type
JT9D-3 Dry
JT9D-3A Wet
JT9D-7 Wet
JT9D-7 Wet
JT9D-7 Wet
JT9D-3A Wet
JT9D-3A Wet
JT9D-7 Wet
JT9D-7 Wet
JT9D-7 Wet
JT9D-3A Wet
CF6-50E
CF6-50E
All 501-D22A
TFE-731-3
JT12A-8
JT3D-3B
Olympus 593
NK-144
Avon 29
CJ805-3
CJ805-23B
Max.
Wt.
W
KLB
710.0
735.0
735.0
735.0
735.0
735.0
735.0
773.0
775.0
775.0
773.0
775.0
800.0
155.0
43.8
42.5
325.0
400.0
396.0
162.0
185.0
255.0
Max. Thrust
Per
Eng.
KLB
43.5
45.0
47.0
47.0
47.0
45.0
47.0
47.0
47.0
47.0
47.0
52.5
52.5
3.7
3.3
18.0
38.05
44.0
11.4
11.65
16.1
Tot.
T
KLB
174.0
180.0
188.0
188.0
188.0
180.0
188.0
188.0
188.0
188.0
188.0
210.0
210.0
14.8
13.2
72.0
152.2
176.0
45.6
46.6
64.4
T/W
0.245
0.245
0.256
0.256
0.256
0.245
0.256
0.243
0.243
0.243
0.243
0.271
0.263
—
0.338
0.311
0.222
0.381
0.444
0.281
0.252
0.252
Noise Level, EPNdB
S/L
@0.35
NM
101.9
103.3
102.1
102.1
102.0
99.5
99.5
101.0
98.2
98.2
97.8
98.4
98.3
93.9
91.5
105.0
103.0
112.0
114.0
103.5
109.0
112.0
T/O @ 3.5 NM
With
C/B
—
112.4
—
_
—
—
—
_
_
—
—
—
93.0
106.0
114.0
117.8
110.0
103.5
116.0
120.0
r NO
C/B
115.0
-
110.6
110.6
110.3
107.6
107.2
112.6
107.0
107.0
107.5
105.3
106.1
98.4
—
—
_
—
_
App
@ 1.0
NM
113.6
114.4
114.4
109.0
112.3
106.8
106.9
111.5
106.2
106.8
106.8
105.0
106.1
99.1
98.5
107.0
117.0
. 114.9
110.0
112.5
106.0
112.0
Notes &
Source of
Data
(2) FAA
(2) FAA
(2) FAA
(1) FAA
(2) FAA
(2) FAA
(2) FAA
(2) FAA
(2) FAA
(2) FAA
(2) FAA
(2) FAA
(2) FAA
(3) FAA
AW&ST
AW&ST
EPA
FAA/EIS
EPA
Rolls-Royce
Rolls-Royce
Rolls-Royce
o
CD
(1) 25-Deg. App. Fl.: (2) 30-Deg. App. Fl.: (3) Turboprop
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(g) 4 ENGINES
-------
I.D.
No.
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
Airplane
Type
VC-10
B-720 B
B-720 B-QN
B-707-120B
B-707-120B
B-707-120B-QN
B-707-120B-QN
B-707-320 B, C
B-707-320 B,C
B-707-320 B, C-QN
B-707-320 B, C-QN
B-747-SR
B-747-SP
B-747-100
B-747-100
B-747-200B
B-747-200B
B-747-200B
B-747-200B
B-747-200F
B-747-200F
Engine
No.
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Type
Conway 42
JT3D-1
JT3D-1
JT3D-1
JT3D-1
JT3D-1
JT3D-1
JT3D-3B
JT3D-3B
JT3D-3B
JT3D-3B
JT9D-7A
JT9D-7A
JT9D-7
JT9D-7
JT9D-7W
JT9D-7W
CF6-50E
CF6-50E
JT9D-7W
JT9D-7W
Max.
Wt.
W
KLB
312.0
234.0
234.0
258.0
258.0
258.0
258.0
333.6
333.6
333.6
333.6
570.0
660.0
710.0
710.0
785.0
785.0
800.0
800.0
785.0
785.0
Max. Thrust
Per
Eng.
KLB
20.37
17.0
17.0
17.0
17.0
17.0
17.0
18.0
18.0
18.0
18.0
47.67
47.67
47.0
47.0
47.0
47.0
52.5
52.5
47.0
47.0
Tot.
T
KLB
81.5
68.0
68.0
68.0
68.0
68.0
68.0
72.0
72.0
72.0
72.0
190.7
190.7
188.0
188.0
188.0
188.0
210.0
210.0
188.0
188.0
T/W
0.261
0.291
0.291
0.264
0.264
0.264
0.264
0.216
0.216
0.216
0.216
0.335
0.289
0.265
0.265
0.239
0.239
0.263
0.263
0.239
0.239
Noise Level, EPNdB
S/L
@0.35
NM
114.0
101.6
96.3
101.3
101.3
95.8
95.8
102.1
102.1
99.2
99.2
99.0
99.0
99.0
99.0
98.0
98.0
98.0
98.0
98.0
98.0
T/0 @ 3.5 NM
With
C/B
110.0
104.7
93.8
108.7
108.7
97.1
97.1
113.0
113.0
102.2
102.2
_
—
—
_
_
101.0
101.0
_
No
C/B
_
—
—
—
—
—
113.6
113.6
110.8
110.8
100.0
104.0
107.0
107.0
107.0
107.0
107.0
107.0
107.0
107.0
App
@ 1.0
NM
115.0
115.5
102.6
116.0
114.0
103.0
107.0
118.5
116.8
106.3
104.0
104.0
104.0
107.0
105.0
106.0
104.0
106.0
103.0
107.0
1040
Notes &
Source of
Data
Rolls-Royce
(1) Boeing
(1) Boeing
(1) Boeing
(2) Boeing
(1) Boeing
(2) Boeing
(1) Boeing
(2) Boeing
(1) Boeing
(2) Boeing
(4) Boeing
(3) Boeing
(3) Boeing
(4) Boeinq
(3) Boeing
(4) Boeing
(3) Boeing
(4) Boeing
(3) Boeing
(4) Rnping
o
o
(1) 50-Oeg. App. Fl.: (2) 40-Deg. App. Fl.: (3) 30-Deg. App. Fl.: (4) 25-Deg. App. Fl.
TABLE 3. SUMMARY NOISE LEVELS FOR TURBOJET PROPELLED AIRPLANES.
(h) 4 ENGINES (CONCLUDED)
-------
I.D.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Airplane
Type
DC-9-30
DC-9-40
Cessna 500
Sabre NA265-80
Learjet 35, 36
Falcon 10
Airbus A 300B
Corvette SN-601
F-28-1000
DC-10-10 1
DC-10-30
L-1011-1
L-101 1-100
B-747-200B
B-747-200B
B-747-SR
B-747-SP
Engine
No.
2
2
2
2
2
2
2
2
2
3
3
3
3
4
4
4
4
Type
JT8D-7A
JT8D-1 5
JT15D-1
CF700-2D-2
TFE 731-2
TFE731-2
CF6-50A
JT15D-4
SPEY555-15
DF6-6D
CF6-50A
RB211-22C
RB211-22B
JT9D-7W
CF6-50E
JT9D-7A
JT9D-7A
Max.
Wt.
W
KLB
94.0
114.0
11.5
23.3
17.0
18.3
302.0
13.89
65.0
386.5
550.0
396.0
450.0
785.0
800.0
570.0
660.0
Max. Thrust
Per
Eng.
KLB
14.0
15.5
2.2
4.32
3.5
3.5
49.0
2.5
9.85
40.3
48.4
42.0
42.0
47.0
52.5
47.67
47.67
Tot.
T
KLB
28.0
31.0
4.4
8.63
7.0
7.0
98.0
5.0
19.7
120.9
145.2
126.0
126.0
188.0
210.0
190.7
190.7
T/W
0.298
0.272
0.383
0.370
0.412
0.383
0.325
0.360
0.303
0.313
0.264
0.318
0.280
0.239
0.263
0.335
0.289
Noise Level, EPNdB
S/L
@0.25
NM
f
97.8
100.5
86.1
91.3
86.7
86.4
95.3
85.4
99.5
96.0
95.7
95.2
94.9
101.5
101.5
102.5
102.5
T/0 @ 3.5 NM
With
C/B
91.7
95.8
-
—
-
79.6
90.2
—
90.0
_
—
_
—
101.0
—
—
No
C/B
—
—
77.7
90.7
83.4
82.9
—
80.4
—
94.6
103.7
96.0
97.4
107.0
107.0
100.0
104.0
App
@ 1.0
NM
97.0
99.4
87.7
100.2
92.2
95.3
101.3
89.5
101.2
99.2
103.0
101.5
101.5
104.0
103.0
104.0
104.0
Notes &
Source of
Data
(1) FAA
(1) FAA
(2) FAA
(3) FAA
(2) FAA
(4) FAA
(5) FAA
(6) FAA
(7) FAA
(6) FAA
(6) FAA
(8) FAA
(8) Lockheed
(3) Boeing
(3) Boeingf
(3) Boeing
(9) Boeing
Approach Flaps: (1) 50°, (2) 40°, (3) 25° (4) 52°, (5) 20° Slats, (6) 35°, (7) 42°, (8) 33°, (9) 30°.
TABLE 4. NOISE LEVELS FOR CURRENT TECHNOLOGY EXISTING AIRPLANES.
-------
i.D.
No.
1a
1b
2
3a
3b
4
5
6
7
8
9
10
11
Airplane
Type
B-727-200
B-727-200
DC-9-32
B-737-200
B-737-200
DC-9
DC-9
DC-8-61
DC-8-62
DC-8-63
DC-8-63F
B-727-300B
BAC-1 11-700
Engine
No.
3
3
2
2
2
2
2
4
4
4
4
3
2
Type
JT8D-109
JT8D-109
JT8D-109
JT8D-109
JT8D-109
JT8D-209
CFM56/JTIOD
CFM56/JT10D
CFM56/JT10D
CFM56/JT10D
CFM56/JT10D
JT8D-217
Spey 604-14
Max.
Wt.
W
KLB
172.5
172.5
108.0
103.0
103.0
127.0
142.0
325.0
335.0
355.0
355.0
222.0
117.0
Max. Thrust
Per
Eng.
KLB
16.6
16.6
16.6
16.6
16.6
18.0
—
—
_
_
19.0
16.9
Tot.
T
KLB
49.8
49.8
33.2
33.2
33.2
36.0
—
_
—
57.0
33.8
T/W
0.289
0.289
0.307
0.322
0.322
0.283
—
_
—
0.257
0.289
Noise Level, EPNdB
S/L
@0.25
NM
92.8
92.8
93.0
85.7
85.7
96.0
89.
92.0
91.0
93.0
93.0
101.0
97.0
T/0 @ 3.5 NM
With
C/B
92.4
92.4
87.0
82.5
82.5
93.0
86.0
95.0
97.0
97.0
97.0
102.0
92.0
No
C/B
98.9
98.9
93.0
84.0
84.0
99.0
91.0
98.0
98.0
100.0
100.0
_
_
App
@ 1.0
NM
100.9
102.5
97.0
99.5
100.8
98.0
96.0
99.0
99.0
99.0
100.0
107.0
99.0
Notes &
Source of
Data
(1) NASA
(2) NASA
(3) NASA
(1) NASA
(2) NASA
Douglas
Noise Levels
± 3 dB and
Max. App.
Flaps
Boeina
BAG
o
NJ
Approach Flaps; (1)30°, (2)40°, (3)50°
TABLE 5. PREDICTED NOISE LEVELS FOR MAJOR ACOUSTICAL CHANGE AIRPLANES.
-------
I.D.
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Airplane
Type
8-7x7
B-7x7
B-7x7
Narrow Body
Narrow Body
Narrow Body
Narrow Body
New Type Design
New Type Design
New Type Design
New Type Design
New Type Design
New Type Design
New Type Design
New Type Design
New Type Design
New Type Design
BAC-1 11-800
DC-X-200
Engine
No.
3
3
3
4
4
4
4
2
3
3
3
3
4
4
4
4
4
2
2
Type
CFM56/JT10D
CFM56/JT10D
CFM56/JT10D
Quiet Eng. A
Quiet Eng. A
Quiet Eng. A
Quiet Eng. A
CFG
RB-211
CF6
JT9D
CF6
JT9D
JT9D
JT9D Wet
JT9D Dry
CF6
CFM56
CF6-50C
Max.
Wt.
W
KLB
255.0
263.0
285.0
330.0
330.0
330.0
330.0 J
302.0
430.0
440.0
530.0
555.0
570.0
710.0
775.0
775.0
800.0
137.0
283.0
Max. Thrust
Per
Eng.
KLB
—
_
—
—
—
_
_
—
_
_
—
22.0
51.0
Tot.
T
KLB
—
_
_
_
_
—
_
_
_
_
44.0
102.0
T/W
_
—
_
—
_
—
_
—
—
_
0.321
0.360
Noise Level, EPNdB
S/L
@0.25
NM
94.5
93.9
93.9
—
_
—
_
97.5
96.5
97.5
96.5
98.5
103.5
103.5
102.5
102.5
102.5
89.7
95.0
T/0 @ 3.5 NM
With
C/B
_
—
—
—
—
—
—
—
_
_
_
_
_
84.4
No
C/B
96.5
95.7
97.7
103.3
98.2
98.9
90.0
93.0
96.0
99.0
101.0
104.0
100.0
107.2
107.2
108.0
106.1
—
95.0
App
@ 1.0
NM
102.9
104.1
104.1
104.1
100.6
—
89.0
102.0
103.5
' 106.5
^ 105.5
108.5
104.5
107.6
106.9
106.9
106.5
, 94.7
98.0
Notes &
Source of
Data
(1) Boeing
(1)
(1)
(1) (2)
(1) (3) (4) "
^(1) (3) (5) "
(3) (6)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1) BAG
(1) AW&ST
o
to
(1) Max. App. Flaps:
(4) Boeing Nacelle:
(2) Peripheral Sam: (3) Inlet & Exhaust Sam Rings:
(5) GE Nacelle: (6) NASA Original Goal:
TABLE 6. PREDICTED NOISE LEVELS FOR NEW TYPE DESIGN AIRPLANES.
(a) I.D. NOS. 1 THRU 19
-------
I.D.
No.
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Airplane
Type
Twin-Jet
Twin-Jet
Tri-Jet
Tri-Jet
Quad- Jet
Quad- Jet
G.A. Twin-Jet
G.A. Twin-Jet
G.A. Twin-Jet
LH2 Subsonic
Jet A Subsonic
LH2 Supersonic
Jet A Supersonic
Lear Star 600
Engine
No.
2
2
3
3
4
4
2
2
2
4
4
4
4
2
Type
CFM56
CFM56
CFM56
CFM56
CFM56
CFM56
QCGAT
QCGAT
QCGAT
Liq. Hydrogen
Fossil-Fuel
Liq. Hydrogen
Fossil-Fuel
Lycoming ALF502'
Max.
Wt.
W
KLB
140.0
140.0
230.0
230.0
355.0
355.0
6.0
9.8
17.0
391.7
532.2
368.0
750.0
32.5
Max. Thrust
Per
Eng.
KLB
22.0
22.0
22.0
22.0
22.0
22.0
1.290
2.224
4.369
28.70
32.69
46.01
89.51
7.50
Tot.
T
KLB
44.0
44.0
66.0
66.0
88.0
88.0
2.58
4.45
8.74
114.80
130.78
184.04
358.04
15.00
T/W
0.314
0.314
0.287
0.287
0.248
0.248
0.430
0.454
0.514
0.293
0.246
0.500
0.477
0.460
Noise Level, EPNdB
S/L
@0.25
NM
_
—
—
—
—
—
79.5
79.5
77.0
87.2
87.8
105.9
108.0
87.0
T/O@3.5 NM
With
C/B
—
—
—
—
—
_
—
—
_
—
—
-
78.0
No
C/B
89.75
88.75
94.75
93.00
98.75
97.25
68.5
70.0
69.0
89.2
94.2
104.3
108.0
_
App
<§> 1.0
NM
98.75
97.25
101.50
99.75
102.25
101.00
85.5
81.0
84.0
_
—
_
-
90.0
Notes &
Source of
Data
(1) GECo.
(2)
(1)
(2)
(1)
(2)
NASA
ICAO
Bulletin
AW&ST
(1) Short Duct: (2) Long Duct
TABLE 6. PREDICTED NOISE LEVELS FOR NEW TYPE DESIGN AIRPLANES.
(b) I.D. NOS. 20 THRU 33
-------
o
Ul
Observer
Category
1
2
3
4
5
6
7
8
9
10
Land Use
Residential
Hospital
Motel and Hotel
School Buildings and
Outdoor Teaching Areas
Church
Office Buildings
Theater
Playgrounds and Active
Sports
Parks
Special Purpose Outdoor
Outdoor/Indoor
Noise Reduction
Level
dB**
15
15
15
15
25
25
35
NA
NA
NA
Windows
Open
Open
Open
Open
Closed
Closed
Closed
NA
NA
NA
Noise Level
Criteria
Ldn
dB
55
55
60
-
-
-
-
-
-
-
Leq
dB
-
-
-
60
•60
70
70
70
60
«•
1 Intruding noise shall not exceed existing Leq minus 5 dB.
" Where knowledge of structure indicates a difference in noise reduction from these values, the
criterion level may be altered accordingly.
TABLE 7. CRITERIA FOR NOISE IMPACT ANALYSIS OF SENSITIVE LAND AREAS.
-------
o
o>
Takeoffs &
Landings Each
Total
No.
420
420
420
420
420
4-Engine
Aircraft
%
33.3
16.7
7.14
4.76
0
Ldn Contour Levels, dB
69 FAR 36
79.8
79.1
78.6
78.1
78.0
ICAO
76.2
75.3
74.7
74.2
74.0
FAA
76.2
75.3
74.7
74.2
74.0
Mean
75.5
74.5
73.8
73.2
72.9
Modified
Mean
75.5
74.5
73.8
73.2
72.9
Available
(Mean
-3dB)
72.5
71.5
70.8
70.2
69.9
Modified
Mean
-3dB
72.5
71.5
70.8
70.2
69.9
Future
69.7
68.5
67.8
67.2
66.9
(a) Air Carrier Airport: Constant operations and variable percent mix.
(b) Air Carrier Airport: Variable operations and constant percent mix.
441
140
44
14
33.3
33.3
33.3
33.3
80.0
75.0
69.9
64.8
76.4
71.4
66.3
61.2
76.4
71.4
66.3
61.2
75.7
70.7
65.6
60.5
75.7
70.7
65.6
60.5
72.7
67.7
62.6
57.5
72.7
67.7
62.6
57.5
69.7
64.7
59.6
54.5
400
127
40
13
4
28.3
28.3
28.3
28.3
28.3
75.0
70.1
65.0
60.1
55.0
71.0
66.1
61.0
56.1
51.0
71.0
61.5
56.4
51.5
46.4
66.7
61.8
56.7
51.8
46.7
66.7
61.8
56.7
51.8
46.7
63.7
58.8
53.7
48.8
43.7
63.7
58.8
53.7
48.8
43.7
60.7
55.8
50.7
44.9
39.8
(c) General Aviation Airport: Variable operations and constant percent mix.
TABLE 8. CONTOUR LEVELS ENCLOSED BY NOISE INDICATOR RECTANGLES.
------- |