Which elements are used by the Integrated Noise Model to compute noise contours?

• A. Flight track information
• B. Aircraft fleet mix
• C. Terrain
• D. Flight track information, aircraft fleet mix, and terrain

Answer: (D)

The Integrated Noise Model uses flight track information, aircraft fleet mix, and terrain to compute noise contours because each factor directly shapes how noise appears on the ground.

Flight track information determines where the noise sources are located and how they move over time. The actual paths, altitudes, and turn patterns of aircraft set the spatial distribution of sound sources, so the contours reflect where noise is generated rather than just a generic ring around the airport.

Aircraft fleet mix accounts for the different noise footprints produced by various aircraft types. Each airplane has its own characteristic noise signature based on engine type, wing design, weight, and configuration. Mixing these differences lets the model weight contributions correctly, producing contours that match the real mix of flights rather than assuming a single generic noise source.

Terrain affects how sound travels from the source to the ground. Hills, valleys, and other elevations can shield, channel, or reflect noise, changing the shape and extent of the contours. Ignoring terrain would misrepresent how shadows and accelerations in sound propagation alter ground-level noise levels.

Together, these elements enable the model to produce accurate spatial boundaries for noise exposure. Weather and other factors also influence propagation, but the combination of flight tracks, fleet mix, and terrain is essential for contour computation.