Code of Massachusetts Regulations › 740 CMR - MASSACHUSETTS PORT AUTHORITY › Title 740 CMR 24.00 - Logan Airport Noise Abatement › Appendix A - NOISE PER SEAT INDEX CALCULATION METHODOLOGY

Current through Register 1525, July 5, 2024
DESCRIPTION
NOISE PER SEAT INDEX (NPSI) is an index value that is
				calculated to effectively represent total noise emissions per seat for
				commercial turbojet aircraft operations at Logan. A NPSI value can be
				calculated for specific aircraft types, individual carrier operations or for
				total airport operations.
METHODOLOGY
On the following pages are descriptions of the methodology for
				calculating an NPSI value; first for a single aircraft type and second, for all
				operations conducted (or to be conducted) by an individual air carrier at
				Logan. The methodology for calculating an NPSI value for the entire airport is
				effectively the same as that for an individual air carrier except that the
				calculation is expanded to encompass all airport operations.
NOISE PER SEAT INDEX (NPSI) CALCULATION
ILLUSTRATION OF CALCULATION FOR SPECIFIC AIRCRAFT TYPES
CALCULATION STEPS:
CALCULATION
RESULTS:
1. Define the characteristics of the subject
						  aircraft in terms of model type, engine type, maximum certificated takeoff
						  weight, maximum certificated landing weight, and stage certification per FAR
						  Part 36. (i.e. 1, 2 or 3)
AC-TYPE
STAGE
ENG. TYPE
MTOW
MLW
DC9-31
1
JT8D-7B
108.0
95.0
B727-200
2
JT8D-15
184.2
154.5
MD80
3
JT8D-217
147.0
128.0
2. Based on the characteristics of the
						  subject aircraft defined in step 1, determine the Part 36 approach and takeoff
						  certification levels in EPNdB published in the then current FAA Advisory
						  Circular (36-lc). For aircraft not certificated under FAR Part 36 (stage 1),
						  find the uncertificated EPNdB noise levels at Part 36 approach and takeoff
						  measurement points published in the then current FAA Advisory Circular (36-2B).
AC- TYPE
TAKEOFF
EPNdB
APPROACH
EPNdB
DC9-31
96.2
105.7
B727-200
98.8
100.4
MD80
90.6
93.1
3. Divide the approach and takeoff EPNdB
						  noise levels by 10.
AC-TYPE
TAKEOFF
DIV BY 10
APPROACH
DIV BY 10
DC9-31
9.62
10.57
B727-200
9.88
10.04
MD80
9.06
9.31
4. Take the antilogarithm to the base 10 of
						  the values derived in step 3 and then add them together.
AC-TYPE
TAKEOFF
APPROACH
TOTAL
DC9-31
4.2E+09
3.7E+10
4.1E+10
B727-200
7.6E+09
1.1E+10
1.9E+10
(Takeoff EPNdB/10) Approach EPNdB/10) 10 +10
MD80
1.1E+09
2.0E+09
3.2E+09
5. Divide the number obtained in step 4 by
						  twice the number of seats on the subject aircraft (counted as seats for one
						  arrival plus one departure) which yields noise energy, per seat. (Step 4 Total)
						  / (2 * total seats on aircraft)
AC-TYPE
NO. OF
SEATS
STEP 4
TOTAL
NOISE ENERGY
/SEAT
DC9-31
116
4.1E+10
1.8E+08
B727-200
148
1.9E+10
62670803
MD80
147
3.2E+09
10849971
6. Take the logarithm to the base ten of the
						  number obtained in step 5 (noise energy per seat) and multiply by ten to yield
						  the NPSI for the aircraft (or effectively decibels per seat). 10 * LOG (Step 5
						  value or Noise Energy Per Seat) 10
AC TYPE
NPSI
DC9-31
82.5
B727-200
78.0
MD80
70.4
NOISE PER SEAT INDEX (NPSI) CALCULATION
ILLUSTRATION OF CALCULATION FOR INDIVIDUAL AIR CARRIER
				OPERATIONS
CALCULATION STEPS:
CALCULATION
RESULTS:
1. Define the characteristics of each
						  aircraft in subject air carrier's fleet (that operate at Logan) in terms of
						  model type, engine type, maximum certificated takeoff weight, maximum certified
						  landing weight, and stage certification per FAR Part 36. (i.e. stage1, 2 or 3)
AC-TYPE
STAGE
ENG. TYPE
MTOW
MLW
DC9-31
1
JT8D-7B
184.2
154.5
B727-200
2
JT8D-7
172.5
150.0
B727-200
2
JT8D-15
184.2
154.5
L1011
3
RB211-22B
430.0
358.0
2. Based on the characteristics of the
						  subject aircraft defined in step 1, determine the Part 36 approach and takeoff
						  certification levels in EPNdB published in the then current FAA Advisory
						  Circular (36-1c). For aircraft not certificated under FAR Part 36 (stage 1),
						  find the uncertificated EPNdB noise levels at Part 36 approach and takeoff
						  measurement points published in the then current FAA Advisory Circular (36-2B)
AC-TYPE
TAKEOFF
EPNdB
APPROACH EPNdB
DC9-31
96.2
105.7
B727-200
100.0
102.6
B727-200
98.8
100.4
L1011
96.0
102.8
3. Divide the approach and takeoff EPNdB noise levels by
						  10.
AC-TYPE
TAKEOFF
DIV BY 10
APPROACH
DIV BY 10
DC9-31
9.62
10.57
B727-200
10.00
10.26
B727-200
9.88
10.04
L1011
9.6
10.28
4. Take the antilogarithm to the base 10 of
						  the TAKEOFF value derived in step 3 and multiply it by the number of DEPARTURES
						  conducted (or to be conducted) in each aircraft type. The calculation yields
						  TOTAL TAKEOFF NOISE ENERGY by aircraft type
AC-TYPE
TAKEOFF
ANTI-LOG
NO. OF
DEPARTURES
TAKEOFF ENERGY
TOTAL
DC9-31
4.2E+09
200
8.3E+11
B727-200
1.OE+10
1200
1.2E+13
B727-200
7.6E+09
1400
1.1E+13
(TAKEOFF EPNdB/10) * TOTAL DEPARTURES 10
L1011
4.0E+09
1100
4.4E+12
5. Take the antilogarithm to the base 10 of
						  the APPROACH value derived in step 3 and multiply it by the number of ARRIVALS
						  conducted (or to be conducted) in each aircraft type. The calculation yields
						  TOTAL APPROACH NOISE ENERGY by aircraft type.
AC-TYPE
APPROACH
ANTI-LOG
NO. OF
ARRIVALS
APPROACH ENERGY
TOTAL
DC9-31
3.7E+10
200
7.4E+12
B727-200
1.8E+10
1200
2.2E+13
B727-200
1.1E+10
1400
1.5E+13
(APPROACH EPNdB/10) 10 * TOTAL ARRIVALS
L1011
1.9E+10
1100
2.1E+13
6. For each aircraft type. add the total
						  takeoff noise energy from step 4 to the total approach noise energy from step
						  5. Then sum the total noise energy for all aircraft types to yield TOTAL NOISE
						  ENERGY generated by the operations conducted by the subject air carrier.
						  (TAKEOFF NOISE ENERGY)+(APPROACH NOISE ENERGY)
AC-TYPE
TAKEOFF ENERGY
TOTAL
APPROACH ENERGY
TOTAL
NOISE ENERGY
TOTAL
DC9-31
8.3E+11
7.4E+12
8.3E+12
B727-200
1.2E+13
2.2E+13
3.4E+13
B727-200
1.1E+13
1.5E+13
2.6E+13
L1011
4.4E+12
2.1E+13
2.5E+13
TOTAL NOISE ENERGY FOR AIR CARRIER
9.3E+13
7. Define the number of seats for each
						  aircraft type. Multiply the NUMBER OF SEATS for each aircraft type by the
						  NUMBER OF OPERATIONS (arrivals + departures) conducted in that aircraft type.
						  Add total seats by aircraft type to yield TOTAL SEATS flown into and out of
						  Logan Airport by the subject air carrier.
AC-TYPE
NO. OF
SEATS
NO. OF
OPERATIONS
TOTAL
SEATS
DC9-31
116
400
46400
B727-200
148
2400
355200
B727-200
148
2800
414400
L1011
302
2200
664400
(NO. OF SEATS ON AIRCRAFT) * (OPERATIONS)
TOTAL SEATS FLOWN BY AIR CARRIER
1480400
8. Divide the total noise energy value obtained in step
						  6 by total seats from step 7. This calculation effectively yields NOISE ENERGY
						  PER SEAT.
TOTAL NOISE ENERGY
TOTAL
SEATS
NOISE ENERGY
PER SEAT
(TOTAL NOISE ENERGY) / (TOTAL SEATS)
9.3E+13
1480400
63098406
9. Take the logarithm to the base ten of the value
						  obtained in step 8 (noise energy per seat) and multiply by ten. The result of
						  this calculation is the NOISE PER SEAT INDEX value for the subject air carrier.
NOISE ENERGY
PER SEAT
63098406
NPSI
78.0
10 * LOG (Step 8 value or NOISE ENERGY PER SEAT) 10