spaschal on DSK3GDR082PROD with CFR

Federal Aviation Administration, DOT

Pt. 36, App. A

being on a particular lateral line. The position of Kr and Qr1 are determined from the
following requirements.
(i) Q1K and Qr1Kr form the same angle q1
with their respective flight paths; and
(ii) The differences between the angles 1
and r1 must be minimized using a method, approved by the FAA. The differences between
the angles are minimized since, for geometrical reasons, it is generally not possible to
choose Kr so that the condition described in
paragraph A36.9.4.2(b)(2)(i) is met while at
the same time keeping 1 and r1 equal.
NOTE: For the lateral noise measurement,
sound propagation is affected not only by
 - inverse square -  and atmospheric attenuation, but also by ground absorption and reflection effects which depend mainly on the
angle.
A36.9.4.2.1 In paragraphs A36.9.4.2(a)(2) and
(b)(2) the time tr1 is later (for Qr1Kr >Q1K)
than t1 by two separate amounts:
(1) The time taken for the airplane to travel the distance Qr1Qr0 at a speed Vr less the
time taken for it to travel Q1Q0 at V;
(2) The time taken for sound to travel the
distance Qr1Kr-Q1K.
NOTE: For the flight paths described in
paragraphs A36.9.4.2(a) and (b), the use of
thrust or power cut-back will result in test
and reference flight paths at full thrust or
power and at cut-back thrust or power.
Where the transient region between these
thrust or power levels affects the final result, an interpolation must be made between
them by an approved method such as that
given in the current advisory circular for
this part.
A36.9.4.2.2 The measured values of SPL(i)1
must be adjusted to the reference values
SPL(i)r1 to account for the differences between measured and reference noise path
lengths and between measured and reference
atmospheric conditions, using the methods
of section A36.9.3.2.1 of this appendix. A corresponding value of PNLr1 must be computed
according to the method in section A36.4.2.
Values of PNLr must be computed for times
t0 through tn.
A36.9.4.2.3 For each value of PNLr1, a tone
correction factor C1 must be determined by
analyzing the reference values SPL(i)r using
the methods of section A36.4.3 of this appendix, and added to PNLr1 to yield PNLTr1.
Using the process described in this paragraph, values of PNLTr must be computed for
times t0 through tn.
A36.9.4.3 Duration correction.
A36.9.4.3.1 The values of PNLTr corresponding to those of PNLT at each onehalf second interval must be plotted against
time (PNLTr1 at time tr1). The duration correction must then be determined using the
method of section A36.4.5.1 of this appendix,
to yield EPNLr.
A36.9.4.4 Source Noise Adjustment.

A36.9.4.4.1 A source noise adjustment, D3,
must be determined using the methods of
section A36.9.3.4 of this appendix.

A36.9.5 FLIGHT PATH IDENTIFICATION POSITIONS
Position

Description

A ...........
B ...........
C ..........
D ..........
E ...........
F ...........
G ..........
H ..........

Start of Takeoff roll.
Lift-off.
Start of first constant climb.
Start of thrust reduction.
Start of second constant climb.
End of noise certification Takeoff flight path.
Start of noise certification Approach flight path.
Position on Approach path directly above noise
measuring station.
Start of level-off.
Touchdown.
Noise measurement point.
Reference measurement point.
Flyover noise measurement point.
Lateral noise measurement point.
Approach noise measurement point.
End of noise certification Takeoff flight track.
Threshold of Approach end of runway.
Start of noise certification Approach flight track.
Position on measured Takeoff flight path corresponding to apparent PNLTM at station K See
section A36.9.3.2.
Position on corrected Takeoff flight path corresponding to PNLTM at station K. See section
A36.9.3.2.
Airplane test speed.
Airplane reference speed.

I ............
J ...........
K ...........
Kr ..........
K1 .........
K2 .........
K3 .........
M ..........
O ..........
P ...........
Q ..........

Qr .........

V ...........
Vr ..........

A36.9.6 FLIGHT PATH DISTANCES
Distance

Unit

Meaning

AB ........

Feet (meters)

AK ........

Feet (meters)

AM .......

Feet (meters)

QK .......

Feet (meters)

QrKr .....

Feet (meters)

K3H ......

Feet (meters)

OK3 ......

Feet (meters)

Length of takeoff roll. The distance
along the runway between the
start of takeoff roll and lift off.
Takeoff measurement distance.
The distance from the start of
roll to the takeoff noise measurement station along the extended
center line of the runway.
Takeoff flight track distance. The
distance from the start of roll to
the takeoff flight track position
along the extended center line of
the runway after which the position of the airplane need no
longer be recorded.
Measured noise path. The distance
from the measured airplane position Q to station K.
Reference noise path. The distance from the reference airplane position Qr to station Kr.
Airplane approach height. The
height of the airplane above the
approach measuring station.
Approach measurement distance.
The distance from the runway
threshold to the approach measurement station along the extended center line of the runway.

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