A Noise Contour is a line on a map that represents equal levels of noise exposure. Massport uses the FAA computer model, the Integrated Noise Model (INM), to calculate annual noise contours. The number of annual flights, aircraft types and flight tracks are critical inputs to the contour model.
The attached maps present the modeled DNL contours for 2011 operations shown in 5-decibel increments for DNL values of 60, 65, 70, and 75 dBA. The contours are generated using Massport'ss FAA-approved version of INM 7.0c with adjustments to account for over-water sound propagation and hill effects in Orient Heights. Logan Airport is the only airport in the country where such modifications have been adopted, and Massport intends that the adjustments be added to all INM-generated contours at Logan Airport until such time as the FAA's standard version of the INM has been enhanced to accommodate hard surfaces and terrain features more accurately.