803 

Federal Aviation Administration, DOT 

Pt. 36, App. A 

(1) XY represents the portion of the meas-

ured flight path that includes the noise time 
history relevant to the calculation of flyover 
and approach EPNL; X

r

Y

r

represents the cor-

responding reference flight path. 

(2) The points Q

0

, Q

1

, Q

n

represent airplane 

positions on the measured flight path at 
time t

0

, t

1

and t

n

respectively. Point Q

1

is the 

point at which the noise was emitted and ob-
served as one-third octave values SPL(i)

1

at 

the noise measuring station K at time t

1

. 

Point Q

r1

represents the corresponding posi-

tion on the reference flight path for noise ob-
served as SPL(i)

r1

at the reference measuring 

station K

r

at time t

r1

. Q

1

K and Q

r1

K

r

are re-

spectively the measured and reference noise 
propagation paths, which in each case form 
the angle 

q

1

with their respective flight 

paths. Q

r0

and Q

rn

are similarly the points on 

the reference flight path corresponding to Q

0

 

and Q

n

on the measured flight path. Q

0

and Q

n

 

are chosen so that between Q

r0

and Q

rn

all 

values of PNLT

r

(computed as described in 

paragraphs A36.9.4.2.2 and A36.9.4.2.3) within 
10 dB of the peak value are included. 

(b) The portions of the test flight path and 

the reference flight path described in para-

graph (b)(1) and (2), and illustrated 

in Figure 

A36–11(a) and (b), 

include the noise time his-

tory that is relevant to the calculation of 
lateral EPNL. 

(1) In figure A36–11(a) XY represents the 

portion of the measured flight path that in-
cludes the noise time history that is relevant 
to the calculation of lateral EPNL; in figure 
A36–11(b), X

r

Y

r

represents the corresponding 

portion of the reference flight path. 

(2) The points Q

0

, Q

1

and Q

n

represent air-

plane positions on the measured flight path 
at time t

0

, t

1

and t

n

respectively. Point Q

1

is 

the point at which the noise was emitted and 
observed as one-third octave values SPL(i)

1

 

at the noise measuring station K at time t

1

. 

The point Q

r1

represents the corresponding 

position on the reference flight path for 
noise observed as SPL(i)

r1

at the measuring 

station K

r

at time t

r1

. Q

1

K and Q

r1

K

r

are re-

spectively the measured and reference noise 
propagation paths. Q

r0

and Q

rn

are similarly 

the points on the reference flight path cor-
responding to Q

0

and Q

n

on the measured 

flight path. 

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