Dimant and Sudan [1995> have recently described a new plasma instability that is excited in the lower ionosphere when a large electric field is applied. This mechanism is intriguing because it is the only low-frequency plasma process that is capable of generating field-aligned irregularities (FAI) at altitudes below 90 km. Thus far, the only evidence for its validity has come from a single in situ measurement by rocket [Blix et al., 1996>. In this paper, we show that a southward-viewing 12.3-MHz radar can be used to probe the D region for the presence of FAI. We show, from a case study, that the Doppler spectra of radar backscatter from southerly azimuths, obtained under appropriate ionospheric conditions, did contain a spectral component that could be associated with this new instability. This low-Doppler-shifted spectral component was accompanied by type-1 echoes that were produced by the well-known modified two-stream instability around an altitude of 95 km.