Code of Massachusetts Regulations › 740 CMR - MASSACHUSETTS PORT AUTHORITY › Title 740 CMR 24.00 - Logan Airport Noise Abatement › Appendix B - Methodology to Establish Tier I and Tier II

Current through Register 1525, July 5, 2024
Criterion Values
The following pages describe the methodology for establishing
				for years subsequent to 1986 both the stage 3 percentage level (hereinafter
				referred to generally as "Tier I") and the NPSI level (hereinafter referred to
				as "Tier II) required of certain air carriers in order to comply with
				740 CMR
				24.03(1)(a) or (b).
I
DATA SOURCES
These calculations will be based on data routinely supplied by
				each carrier in compliance with the reporting procedures specified in
				740
				CMR 24.00. This data will include the
				following:
A Aircraft Type Characteristics
Each aircraft type in a respective carrier's fleet that
				operates at Logan Airport will be defined in terms of the following
				characteristics.
- model series
- engine type
- maximum certificated landing weight
- maximum certificated takeoff weight
- Part 36 certificated approach and takeoff noise level in
				EPNdB
- Part 36 stage certification (i.e.,1, 2, or 3)
B. Operations by Aircraft Type
The number of operations to be conducted by aircraft type as
				defined in step IA will be reported by the respective carriers. Reported
				operations will be uniformly changed based on projected growth for the upcoming
				year.
II
CALCULATE ANNUAL AIRPORT CUMULATIVE
				NOISE
Based on the operations data by and aircraft type
				characteristics supplied above and projected growth calculate annual cumulative
				noise at Logan Airport for the upcoming year per the following steps:
A. For each carrier and aircraft type determine the proportion
				of scheduled daytime and nighttime takeoffs and landings conducted during the
				reporting period. The proportions will be computed using the OAG database.
				Daytime is defined as 7:00 AM to 10:00 PM and nighttime from 10:00 PM to 7:00
				AM. Based on the proportions above, sub-divide the number of operations
				reported for each aircraft type into daytime departures, nighttime departures,
				daytime landings, and nighttime landings. Compute the total noise energy
				generated by the operations conducted in individual aircraft types as follows:
1. Take the antilogarithm to the base 10 of the TAKEOFF EPNdB
				noise level defined in IA and multiply it by the number of daytime departures.
(TAKEOFF EPNdB/10)
10 X Total daytime departures
2. For nighttime departures, take the antilogarithm to the base
				10 of the same takeoff EPNdB noise level and add 10 to account for the 10dB
				weighting for each operation conducted at night. Multiply this value by the
				number of nighttime departures.
((TAKEOFF EPNdB+10)/10)
10 X Total daytime arrivals
3. Take the antilogarithm to the base 10 of the Approach EPNdB
				noise level and multiply it by the number of daytime arrivals.
(APPROACH EPNdB 10)
10 X Total daytime arrivals
4. As in step 2 above, add the 10 dB nighttime penalty to the
				antilogarithm to the base 10 of the approach EPNdB level and multiply it by the
				number of nighttime arrivals.
((APPROACH EPNdB+10)/10)
10 X Total nighttime arrivals
5. Add the values derived in steps 1 through 4 above to yield
				the total noise energy generated by the operations conducted by each aircraft
				type.
B. Add the total noise energy value computed for each aircraft
				type to yield total noise energy for all airport operations.
C. Take the logarithm to the base ten of the total airport
				noise energy value obtained in step IIC and multiply by ten. The result of this
				calculation is the cumulative EPNdB noise level for all airport operations.
III
ANNUAL GOAL ASSESSMENT
Compare the cumulative annual EPNdB level computed in step II
				to the 1984 base case level. of 156.34dB. If the computed level falls within
				the range of 0.1 to 0.3dB below the 1984 base level then no adjustment in the
				stage 3% share for the Tier I criterion or the NPSI for Tier II is
				necessary.
If the computed annual noise level is not at a minimum of 0.1
				dB below the 1984 base level then Tier I and Tier II criterion will require
				adjustment to produce greater cumulative noise reduction. If, on the other
				hand, the computed noise level proves to be greater than 0.3 dB below the 1984
				base level, then the Tier I and Tier II criteria will be adjusted to bring the
				cumulative noise reduction back within the range of the projected goal of the
				regulations.
The methodology for calculating the adjustment to the Tier I
				stage 3 % criteria and the Tier II NPSI are described in the following.
IV
TIER I AND TIER II ADJUSTMENT
				METHODOLOGY
A Adjustment where cumulative noise not reduced in compliance
				with goals.
In this case the Tier I stage 3% and the Tier 2 NPSI criteria
				have to be constrained further to produce at a minimum a reduction in
				cumulative airport noise of 0.1 dB. The method to compute the required
				adjustments follows:
The methodology is based on the use of the database developed
				in section II to derive the cumulative airport noise level.
1. Determine the increase in the stage 3 share necessary to
				achieve the minimum 0.1 dB noise reduction as follows. First, compute the stage
				3 share of the existing fleet. Next, holding seats and day/night proportions
				constant substitute stage 3 for stage 2 operations and then recalculate the
				cumulative noise level. Repeat this calculation in an iterative manner until
				the 0.1 dB minimum reduction in cumulative noise is accomplished. Recalculate
				the stage 3 share for the adjusted fleet that meets the goal. Then compute the
				net difference between the stage 3 share for the existing fleet that did not
				satisfy the goal and share for the adjusted fleet that met the goal. Add the
				net difference in the stage 3 share to the Tier I % criteria scheduled to be
				used during the upcoming evaluation period.
2. Determine the reduction in the NPSI criteria for Tier II th
				at is necessary to achieve the minimum cumulative noise goal. First compute the
				NPSI value for the existing fleet per the methodology described in attachment
				Appendix A Next, compute the NPSI for the fleet defined in step IV AI that
				satisfied the noise goal. Compute the net difference between the NPSI for the
				adjusted fleet that meets the goal and the existing fleet that did not meet the
				goal. Subtract the computed difference from the NPSI value scheduled to be used
				for the upcoming evaluation period, which effectively reduces the NPSI value
				scheduled to be used for the upcoming evaluation period, which effectively
				reduces the NPSI in order to achieve a greater reduction in cumulative noise.
B. Adjustment Where Cumulative Noise Reduction in Excess of
				Goal
In this case, Tier I stage 3 share and the Tier II NPSI
				criteria can be relaxed to produce a maximum reduction in cumulative noise of
				0.3dB. The method to compute the required adjustment follows. In each case, the
				methodology essentially reverses the procedures described in section IV
				A
1. Again, using the fleet database developed in section II,
				determine the decrease in the stage 3 share that would produce a maximum noise
				reduction of 0.3 dB. First, compute the stage 3 share of the existing fleet.
				Next, holding total seats and day/night proportions constant sub stitute stage
				2 for stage 3 operation iteratively until cumulative noise reduction is cut
				back to 0.3 dB. Then recalculate the stage 3 share for the adjusted fleet mix
				that produces noise reduction within the goal range. Next, compute the net
				difference between the stage 3 share for the existing fleet that produced
				excessive noise reduction and for the projected fleet that produces the maximum
				reduction goal. Finally, subtract the computed net difference in stage 3 share
				from the Tier I share scheduled to be used for the upcoming evaluation
				period.
2. Determine the increment to be added to the NPSI value for
				Tier II th at is consistent with a maximum cumulative noise reduction of 0.3
				dB. First, compute the NPSI for the existing fleet that produced the excessive
				noise reduction (per the methodology in Appendix A). Next, compute the NPSI
				value for the projected fleet that produced the preferred maximum noise
				reduction in step B1. Then compute the net difference between the NPSI for the
				existing fleet that produced excessive noise reduction and the adjusted fleet
				mix that meets the maximum goal. Then add the computed difference to the NPSI
				value scheduled to be used during the upcoming evaluation period which
				effectively relaxes the constraint on cumulative noise
				reduction