• Revised preliminary noise contour maps for each alternative, and a map depicting the 2005 base case
• Enlarged maps for each alternative, shaded for comparison with the 2005 base case
• An annotated map depicting necessary corrections in the offset approach track for runway 17R
• Materials distributed by consultants in the previous meeting, for reference

The committees reviewed the Study Group’s noise abatement strategies once more, representing varying preferences for use of the two main runways in operations north of the airport, and varying divergences of operations south of the airport. Members then examined the revised contour maps forwarded by the consultants. Model inputs had been adjusted to (1) apply the three strategies to "exceptions to contraflow" operations along with the rest, and (2) align approach and departure paths north of the west runway in an effort to narrow the contour there. A need to correct the placement of the offset approach path for runway 17R was accentuated in these runs by the placement of additional traffic there; consultants acknowledged the problem and committed to correcting it in future runs.

Nonlinear effects of the noise scale had similar impact on the respective alternatives as before, with disproportionate effects observed for relatively small or relatively large changes. Committee members focused on the specific changes undertaken in these runs:

• Aligning approach and departure paths had the anticipated effect north of the west runway, of narrowing the noise contour and drawing it out of the adjoining neighborhoods.
• Shifting "exceptions to contraflow" operations to follow the same alternative runway use patterns as other operations had a surprisingly large impact, shifting contours by several dB. The results now much more closely resemble patterns one would expect from the strategies being evaluated.

The second point shows exceptions to contraflow as a much bigger contributor to the airport noise problem than expected, and thus makes it all the more urgent to develop means to manage it. There remains a range of opinion about the obligatory nature of the contraflow procedure, and even its applicability to carriers other than UPS. But so far as the Study Group can credit these model results, there can be no doubt of the impact these operations have, nor of the resulting mitigation challenge they present if they can’t be abated.

The committees considered what potential steps might make progress on this issue. Management measures might include calling on carriers to identify their current and projected plans to conduct such operations on a regular basis. Meetings with carriers, either singly or collectively, could then lay out the impact these operations have on the community, and consider alternatives to accomplish their purposes. Such a process could (1) collect accurate data on the extent and nature of these operations; (2) educate carriers on their costs as well as benefits; (3) expose alternatives, if any, for consideration; (4) provide a basis to legitimize unavoidable cases; and ultimately (5) reduce the problem to a minimum that can be "managed by exception".

Members agreed that a suitable approach would engage the RAA with carriers, via the existing Airline Properties committee structure, and with observation available to Study Group principals as required. Dorn Crawford and Joe Richardson had agreed to renew and extend their discussion of specific steps toward this end.

Tom Marks asked members to consider how this process should affect the modeling of alternative noise strategies. The committees agreed to seek a model run that would show contours without any exceptions to contraflow, to compare to the current case of unconstrained exceptions. This will help isolate the effect of these operations for discussions with users. These discussions will help determine what exceptions should remain to be portrayed in final modeling.

A question was raised of whether to expect new runs of the current cases with a corrected offset path, for closer comparison. Since it wasn’t clear whether such runs were already under way, Bob Brown agreed to take this up with the consultants.

Returning to the contours presented, the committees resumed study of effects south of the airport. Members noted the generally longer and narrower shape of the contours there, regardless of the strategy depicted. They judged this the probable result of extended flight tracks. Under existing procedures used in the base case, aircraft turn to course just south of I-265 (the "270º radial"); new flight tracks for the three strategies, on the other hand, delay these turns nearly to the county line. Noise exposure consequently changes, but the net effects on populations aren’t yet clear. The committees pledged to examine impact statistics closely when they come, to see whether further flight track adjustments are needed.

More generally, members recalled measures adopted in the Study Group’s common program to refine flight tracks in formulating and prescribing standard approaches and departures (STARs and SIDs). These measures were affirmed as necessary and appropriate next steps, beyond modeling, to abate noise exposure in the community. Existing approach and departure procedures provide ample room for refinement of paths, waypoints and maneuvering altitudes, within existing FAA guidelines. Such measures could greatly relieve noise impacts beyond the nominally critical contours, especially in elevated areas, and in areas that might otherwise have increased overflights. The Navigation Committee, in particular, anticipates focusing close attention on these measures once the core modeling effort is in hand.

The chairs agreed to meet again, either individually or jointly, once new results are received and progress registered on managing contraflow exceptions. The Study Group chair will undertake a redraft of his written update to the remainder of the Study Group summarizing ongoing activity. The meeting adjourned at 9:10 PM.

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