INM 5.1 technical manual

Final Jan 93 - Dec 97

NTL-AVIATION-AVIATION ; NTL-AVIATION-Aviation Energy and Environment ; NTL-ENERGY AND ENVIRONMENT-Aviation Energy and Environment ;

The Federal Aviation Administration, Office of Environment and Energy (FAA, AEE-120) has developed Version 5.1 of the Integrated Noise Model (INM) with support from the John A. Volpe National Transportation Systems Center, Acoustics Facility (Volpe Center) for development of the acoustic computation module and from the ATAC Corporation for systems integration, development of the graphical interface, and methods for computing aircraft flight profiles and constructing flight paths, which are processed by the acoustics module. The Technical Manual for INM 5.1 describes the flight-path methodology (Chapter 2), along with the basic methodology employed by the INM to compute a noise-level or timeabove metric at a single, user-specified observer, or at an evenly-spaced, regular grid of observers (Chapter 3). The noise/time computation methodology is presented in a concise step-by-step fashion, and includes a description of: (1) the computation of the flight-segment geometric and physical parameters; (2) the flight-segment noise-level interpolation process; (3) the acoustic impedance adjustment; (4) the flight-segment noise-fraction adjustment for exposure-based metrics; (5) the airspeed adjustment for exposure-based metrics; (6) the lateral attenuation adjustment; (7) the ground-based directivity adjustment for observers behind start-of-takeoff-roll, as well as for computing metrics associated with runup operations; (8) the metric computation process; and (9) the development of a recursively-subdivided irregular grid methodology, which is used for computing noise contours (Chapter 4).

Volpe