Noise Power Distance Re-Evaluation

Project Number: 043
Category: Noise, Tools

The standard technique for evaluating noise from flight procedures is through Noise Power Distance (NPD) relationships. Noise calculations in the Aviation Environmental Design Tool (AEDT) rely on NPD curves derived from aircraft certification data. This dataset reflects representative aircraft families at set power levels and aircraft configurations. Noise levels are obtained as a function of observer distance via spherical spreading through a standard atmosphere. Other correction factors are applied to obtain the desired sound field metrics at the location of the receiver. The current NPD model does not take into account the aircraft configuration (e.g., flap settings) or alternative flight procedures being implemented. This is important as the noise characteristics of an aircraft depend on thrust, aircraft speed and airframe configuration, among other contributing factors such as ambient conditions.

The outcome of this research will be a suggested NPD + configuration (NPDC) format that enables more accurate noise prediction due to aircraft configuration and speed changes. While NPDC work to improve the accuracy of source noise prediction, they must be coupled with appropriate procedures and flap schedules such as are being developed under ASCENT Project 45.


Georgia Tech will leverage domain expertise in aircraft and engine design and analysis to evaluate gaps in the current NPD curve generation and subsequent prediction process as it relates to fleet noise prediction changes from aircraft configuration and approach speed. The team will use EDS physics based modeling capabilities to conduct a sensitivity analysis to identify additional parameters to be included in the NPDC (NPD + Configuration) curve format. The team will also seek out airport noise measurements to assess the increased accuracy of the developed NPDC format.

Last Updated 7/19/2023


Representative NPD+C Curves for small through large vehicle classes
Spring 2017 ASCENT Advisory Board Presentation

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Project data is available in the 2016 annual ASCENT COE Report and will be updated in the 2017 COE Report.

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