Method for Predicting Lateral Attenuation of Airplane Noise AIR5662

This document describes analytical methods for calculating the attenuation of the level of the sound propagating from an airplane to locations on the ground and to the side of the flight path of an airplane during ground roll, climbout after liftoff, and landing operations. Both level and non-level ground scenarios may be modeled using these methods, however application is only directly applicable to terrain without significant undulations, which may cause multiple reflections and/or multiple shielding effects. This attenuation is termed lateral attenuation and is in excess of the attenuation from wave divergence and atmospheric absorption.

The methods for calculating the lateral attenuation of the sound apply to:

The calculation methods do not apply for calculation of lateral attenuation for:

Helicopters are highly directional sources. While the specific method described herein is not wholly applicable to the prediction of lateral attenuation of helicopter noise, some components (see 6.1) may be applicable.

Relationships presented herein were derived utilizing data from microphones placed 1.2 m above the local ground surface. The relationships may be appropriate for use at receivers at other heights, however care should be taken in such applications.