An X-band Doppler radar in the tail of a WP-3D research aircraft has been used to conduct tests which demonstrate that technology developed for ground-based Doppler radar can be applied to an airborne system. The Doppler spectra of meteorological targets and chaff have been measured with the airborne radar, and these measurements compared favorably with data obtained by wind sensors on the aircraft and with measurements made with a ground-based Doppler radar. This letter describes the airborne Doppler radar and the preliminary test results.