  We investigate the use of HI data to resolve the near/far ambiguity in
kinematic distances of massive young stellar object (MYSO) candidates.
Kinematic distances were obtained from 13CO 1-0 spectral line observations with
the Mopra Telescope towards 94 candidates selected from the Red MSX Source
(RMS) survey in the fourth Galactic quadrant. HI data from the Southern
Galactic Plane Survey (SPGS) was used in conjunction with the HI
self-absorption technique to determine the near or far distance. We resolved
the kinematic distance ambiguity to 70% of the sources. We can also
simultaneously solve for any multiple line-of-sight component sources. We
discuss the advantages and disadvantages of this technique in comparison with
other methods, and also perform confidence checks on the reliability of using
the HI self-absorption technique. We examined the projected location of these
sources in both the Galactic plane and longitude-velocity diagrams to ascertain
any recognisable spiral arm pattern. Although no obvious spiral pattern was
found when compared to that proposed by Cordes & Lazio, far distance sources
tended to lie on or near spiral arm loci. Near distance sources, however, had
peculiar velocity uncertainties consistent with the separation between the
spiral arms themselves. The longitude-velocity plot shows a more consistent
picture, with tangent points of the spiral arm loci easily seen. We conclude
that using the HI self-absorption technique to determine kinematic distance
ambiguities is a quick and reliable method in most cases, with an 80% success
rate in determining the correct designation of whether an object is at the near
or far distance.
