[en] The effect of deviations from statistical equilibrium in planar channeling on the planar scan of impurity yield has been theoretically investigated. The computer programme determines, at several depths in the crystal, the overlap between the impurity occupancy and ion trajectories in a static continuum potential. The impurity thermal vibrations are represented by a gaussian impurity distribution about a mean displacement from lattice planes. The overlap summed over all trajectories with a given incident angle is treated as a measure of the close interaction yield from impurity atoms. The 2 MeV He⁺(110) dip for substitutional impurities in Si so calculated exhibits a strong dependence on the impurity depth even upto depths of 1000A. This is attributed to the large oscillations in impurity yield with depth for a fixed incident angle. Similar effect has been obtained for several incident energies and planar channels and with other impurity sites. The implications of these results in planar channeling experiments for impurity lattice location are discussed. (auth.)