• Proposed agenda
• Notes of the previous meeting
• Discussion paper on screening of noise abatement measures
• Extracts of Jan 13 consultant presentation on abatement measures, screening results, noise abatement strategies, and suggested noise mitigation measures and screening criteria

The agenda was adopted, and notes of the committee’s November 30 meeting were approved. The committee agreed to focus its efforts on reviewing the consultants’ screening of noise abatement measures, and the resulting strategies proposed for analysis.

Because very specific meanings have been assigned to terms used to label the major elements of the study effort, the committee reviewed its definitions:

• abatement: actions taken to affect the size and shape of noise contours. Alternatively, operational measures, or things done to aircraft
• mitigation: actions taken to relieve impact of noise exposure after abatement. Alternatively, land use measures, or things done on the ground
• measures: individual steps to abate or mitigate noise – what to analyze
• screening criteria: measures of merit to conduct screening: how to analyze
• screening: preliminary analysis to evaluate measures, and develop strategies
• strategies: combinations of abatement measures to be analyzed together in detail for net effect
• alternatives: final combinations of abatement strategies and mitigation measures for selection of the preferred noise compatibility program

Committee discussion began with a review of abatement screening criteria, comparing and contrasting criteria approved by the Study Group with those actually applied. The order and hierarchy of the criteria the consultants used in screening were so different from those they proposed in October that validation was difficult and time-consuming. The committee finally concluded that the principal criteria originally listed could be loosely discerned in the screening, though not necessarily with the same scope. Specific refinements adopted by the Study Group in December did not appear to have been applied: screening results did not include any indication of noise modeling to evaluate measures, and no cost analysis appeared. This led to some concern over the robustness of the recommendations coming out of the screening process.

By the same token, some members expressed concern over the robustness of certain aspects of the noise model itself. Residents of areas of higher elevation who have had chronic difficulty expressing their noise problem in the study’s terms are increasingly aware that the model takes no account of elevation in estimating noise exposure. The committee now awaits illustrative calculations by the consultants using industry ‘rules of thumb’ to give adjusted noise exposures for more elevated areas of the community.

The balance of the meeting was devoted to a review and assessment of the recommendations themselves. Four of the eight abatement categories were covered in the time remaining.

Runway Use Programs
The Study Group had prescribed five measures for analysis in this category. Three were hypotheses designed to test the limits of preferential uses of the two main runways; the remaining two were to determine the effects of varying rules for the direction of operations.

• The existing preference for the east runway was to be compared to the other limiting choices available: preference during daytime hours only; no preference; or reversed preference, favoring the west runway. Effects of intermediate choices could then be estimated between these extremes. Consultants recommend the first two choices be ‘combined’ into one, in which preference would be limited to nighttime only, and the third be changed to reverse preference only at night. The committee noted that the two resulting measures are fundamentally different from the three approved by the Study Group, and do not appear to cover the same breadth for analysis. A search of screening results revealed only general comments about runway preference, without discrimination or justification of alternative choices.

• Wind speed was the sole factor the consultants used to predict the direction of runway use for modeling the base case. To compensate for other decision factors not represented (precipitation, storm activity, wind shear, runway maintenance, etc), they estimated a threshold value of 3 knots tailwind, instead of the 7 knots specified by current policy. The sensitivity of this choice was not examined, despite correspondence with the committee that verified the need. One prospect suggested in this exchange was to formulate a noise abatement measure for analysis that would have the same role, showing whether a change in tailwind threshold would have a major effect on noise exposure. The committee, and in turn the Study Group, adopted a measure that would assess the effect of raising the threshold from 7 to 10 knots, for purposes of analysis. Now, the committee noted, the consultants recommend that this measure not be analyzed, because the value exceeds current FAA policy for actual operations. No other criteria were examined, as the measure did not appear in the screening report.

• Exceptions to contraflow operations arising from scheduling, rather than weather conditions, are among the most vexing of nighttime noise problems. These happen regularly when flights depart during the arrival phase of contraflow, or arrive during the departure phase, operating north of the airport over heavily populated neighborhoods in both cases. The Study Group sought ideas and analysis that could minimize occurrence, and put forth a measure to assess potential benefits. Rather than exploring concrete ideas (e.g. rescheduling of out-of-cycle flights, opening of one or more ‘windows’ in contraflow operations to permit other flights, etc), however, consultants recommend against further analysis based on unspecified "capacity and delay implications." The committee noted again, aside from a favorable assessment of the contraflow program in general, that further evaluation or elaboration was not to be found in the screening results.

Flight Track Changes
Three measures were set forth in this category: exploring uniform turning criteria for departing aircraft; restoring an agreed 15&Mac251; divergence for west runway departures; and prescribing the divergence for all departing flights (already done northbound, but not southbound). The committee agreed that the consultants’ comments on these measures were largely unresponsive, and that the only pertinent screening result was a general assessment of the merits of noise abatement flight tracks.

• For the various options listed for consideration in seeking a uniform turning procedure, the comment was that such criteria are "recommended for use," without further specification.

• For changing the runway divergence to the originally agreed 15&Mac251; from the currently applied 20&Mac251;, the reaction was "straight-out flight tracks recommended during non-peak periods"

• For applying the divergence to all departures, consultants advised "adhere to noise abatement flight tracks"

With no additional detail available in the screening report, the committee was not persuaded that any of the Study Group’s measures in this category should be amended or abandoned.

Approach Procedures
The bulk of the measures listed in this category were aircraft maneuvering procedures adopted from earlier suggestions by the consultants. Accordingly, their early dismissal by the same consultants in this preliminary screening was not of great consequence to the committee, except in the impression it leaves of a ‘check-the-box’ process that adds little to the community’s knowledge base.

A more troubling point the committee noted, however, was the dismissal of several of these measures simply for an imputed lack of effect inside the 65 DNL contour. Members observed that, even if substantiated, such a finding, while it might justify dropping a mitigation measure requiring Federal resources, would not so justify dropping an abatement measure that could otherwise attract a consensus of the parties.

The above issues aside, the Study Group’s principal focus in this category was on measures that would direct arriving aircraft into narrower and more consistent paths that could either be routed away from incompatible areas, or become the sharp focus of future mitigation efforts. These included (1) directing all arriving aircraft to existing instrument approaches; (2) not issuing visual flight plans, nor permitting cancellation of instrument plans on approach, except for pilot-declared emergency; and (3) developing noise-optimal standard approach routes (STARs) for the airport. Only the first two measures appeared in the screening report, with limited application recommended for the second. The committee finally located the first measure in a different category, "Navigation Technology," where consultants recommend against it for potential capacity implications. The third, STARs, which several committee members characterized as the most promising, was not screened, but was briefed as "not recommended – no effect on 65 DNL." Again, this left the committee unpersuaded.

Departure Procedures
Once more, several aircraft maneuvering procedures suggested earlier by the consultants were considered, with close-in and distant abatement procedures drawing endorsement as voluntary measures; reduced thrust departures did not appear in screening, but were recommended against for unspecified safety reasons. Committee members questioned the practicality of applying different departure procedures to north and south runway use, mirroring similar concerns about turning criteria raised earlier. The likely effect of "voluntary" measures was also debated, with a clear need emerging for more specificity on conditions for observing such a measure or not.

Developing standard instrument departure procedures (SIDs) was endorsed in the screening report, though under a different category, "Flight Track Management." The committee looked forward to the emergence of specific candidate procedures that would minimize incompatible exposure.
The final measure adopted by the Study Group in this category proposed use of a prospective runway extension/overrun area to permit takeoffs at an earlier point on the runway. This measure was not screened either, but from the consultants’ recommendation and accompanying briefing, it appeared that the specific prospects cited had not been examined. The recommendation against this measure appeared instead to rely on (1) the unsuitability of an unpaved or under-structured emergency overrun area for normal operations, and (2) the costs of constructing such an overrun entirely for noise abatement purposes. This measure thus remains to be evaluated in the context of Louisville’s specific plans and prospects.
Owing to the late hour, and the number of items remaining to be addressed, the chair proposed that the committee meet again under the same agenda to complete its work. The committee agreed to reconvene at 7 PM on January 28 in the same location. The meeting adjourned at 10 PM.

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