It was recently shown by Kofman et al. (1993), that an electron heat f
low correction is essential in interpreting the difference between the
frequency of upshifted and downshifted electron plasma lines. However
, whereas the agreement with the frequency difference correction was e
xcellent for the lowest values of the temperature gradient, there was
a substantial discrepancy for the highest value of this gradient. We s
how that excellent agreement can be obtained in the latter case as wel
l by taking into account the effect of runaway electrons on the heat f
low. It is suggested that a proper account of the heat flow including
the correction for runaways may make it possible to reliably determine
the field aligned currents from incoherent scatter radars observation
s.