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.