Meeting Notes : Navigation Committee
Committee notes reflect the views and opinions of the committee members and not necessarily those of the Noise Compatibility Study Group, Coordinating Council, Regional Airport Authority of Louisville and Jefferson County, or the Consultant Team.
Attendees: Terry Borne, Dorn Crawford, Teresa Cusick, Mary Rose Evans, George Hudson, John Lanning, John Sistarenik, Bob Welch, Mike Zanone
The meeting was called to order at 7:00 PM. The sole agenda item was discussion and refinement of an offset approach for runway 17R - that is, approaching the west runway from the north. The chair reported several exchanges of modeling assumptions with consultants, which had still not achieved a clear and complete representation of this key element of the Study Group's noise abatement strategy. Materials recirculated to support discussion included:
• Noise contour maps for 1998 and 2005 base cases
• Draft modeling assumptions for noise abatement strategies
• Committee sketch of offset approach
• Existing SDF approach plates
• Enroute navigational maps
Notes of the committee’s last meeting were approved. Committee members then broke into several smaller discussions of individual aspects of the offset approach and related matters. At the time appointed to wrap up, the chair solicited observations and insights to help consolidate the approach. The following key points emerged:
• The trace of the path, and specifications for following it accurately and consistently, are critical to the success of the noise abatement strategy. The Study Group is aiming to take advantage of a corridor of railyards and industrial and commercial land uses northwest of the west runway. This is the only path north of the airport that avoids heavily populated residential areas. But in places it's quite narrow, and sensitive facilities and neighborhoods lie to either side. Its promise for providing relief elsewhere is great, but it must be defined carefully and followed closely
• Fifteen degrees is the appropriate offset. The available path to minimize noise exposure, as noted above, is narrow. The best offset to follow this path depends to some extent on where it crosses the runway centerline. But much less than 15 degrees loses the prospect of aligning approach and departure tracks for minimum dispersion. Much more than 15 increases overflights of West End neighborhoods, which, though outside critical noise contours, is still undesirable. Fifteen degrees offers the best prospect of an optimum track.
• A "missed approach point" (a.k.a. "visual decision point") should be set along the offset at two miles from runway threshold. Based on all the examples the committee examined of offset approach plates at other airports, it's this point, rather than the intercept of the runway centerline, that defines the critical parameter for the approach. This is the point where the pilot must have the runway in sight, and be free to maneuver to the centerline for a straight-in landing. A point about two (statute) miles from runway threshold lies just south of the University campus, and is marked by a nearby small radio tower. This point clears the most critical section of the approach path, and still provides adequate time and space for the necessary maneuver to land - or fly away, if the approach is missed.
• Weather minima of 1000 feet ceiling and 4 miles visibility will permit over 90% usage of this approach. Obviously the objectives of the noise abatement strategy are best served by criteria that permit the use of this approach as consistently as possible. The missed approach point contemplated above would normally place approaching aircraft at a little over 600 feet, two miles from touchdown. Participating pilots judged that weather minima of 1000 feet and 4 miles would give an adequate safety margin to define the approach. Initial estimates from consultants based on historical weather data would permit the approach with these minima to be used more than 90% of the time.
The chair proposed to convey these points to consultants for use in formulating the approach for modeling. He proposed to call another meeting when results of upcoming analysis begin to take shape, to prepare the committee for its role in the next Study Group meeting. He also proposed to make further inquiries on the status of the methodology peer review, and have results of those inquiries ready for dissemination and review. This was agreed, and the meeting adjourned at 9 PM.