The stabilized platforms used in marine and airborne gravimeters behave like damped long-period pendulums. When subjected to horizontal accelerations they tilt, resulting in gravimeter reading errors. The amount of tilt depends on the ratio of the period of the horizontal motion to that of the platform and is negligible if this ratio is less than about 0.1 (LaCoste, 1967). This condition can be achieved in straight and level flight using an auto pilot, provided the platform period is set to a sufficiently long period (Brozena and Peters, 1988). Course changes are sometimes unavoidable, however, resulting in lost data (Bell et al., 1991; Brozena, 1984). The aim of this paper is to show that such data loss is unnecessary since the tilt, and hence the gravimeter error, can be accurately modeled from the horizontal accelerations. Moreover the technique will improve data quality whenever long period horizontal accelerations occur. Measuring these accelerations is now straightforward with differential carrier phase GPS.