A noise impact model (NIM) has been developed that allows the user to examine the impact that quieter aircraft technologies might have on air carrier operating efficiency at major U.S. airports. The analyst selects one of 16 available airports and one of three case years for study, chooses a set of flight tracks, and has the option of reducing the noise of one or more aircraft. Two sets of flight tracks are available for most airports; one that represents actual current conditions, including noise abatement tracks, and a second set that offers more efficient routing. NIM computes the resultant noise impact and the time and distance saved for each operation on the more efficient, alternate tracks. In addition, NIM offers the option of examining the effect that runway use patterns have on capacity and delay for three airports. Noise impact is characterized in three ways; the size of the noise contour footprint, the number of people living within the contours, and the number of homes located in the contours. A World Wide Web implementation of NIM will be available this year through the Aviation System Analysis Capability at www.asac.lmi.org.