The finite length of seismic arrays results in smeared estimates of the plane-wave decomposition of the recorded wave field. The smearing is a fundamental property of plane-wave decomposition; it can be reduced but not eliminated. If not accounted for, this smearing can have a significant effect upon the waveform inversion of plane-wave seismograms. This paper illustrates the effects of limited spatial aperture on the plane-wave decomposition and demonstrates that these truncation artifacts can be described by a linear ray parameter-dependent filter. Experiments with synthetic data indicate that including the effects of limited aperture in the forward model of an iterative inversion produces a stable inversion result without significantly reducing the information content of the data. The method is illustrated with synthetic data derived for an earth consisting of elastic, isotropic, flat layers.