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
Universal Citation: 740 CMR 24.00 MA Code of Regs A
Current through Register 1531, September 27, 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 | |||||
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