  Errors in the kinematic distances, under the assumption of circular gas
orbits, were estimated by performing synthetic observations of a model disk
galaxy. It was found that the error is < 0.5 kpc for most of the disk when the
measured rotation curve was used, but larger if the real rotation curve is
applied. In both cases, the error is significantly larger at the positions of
the spiral arms. The error structure is such that, when kinematic distances are
used to develope a picture of the large scale density distribution, the most
significant features of the numerical model are significantly distorted or
absent, while spurious structure appears. By considering the full velocity
field in the calculation of the kinematic distances, most of the original
density structures can be recovered.
