The Poker Flat, Alaska, MST radar and the Chatanika incoherent-scatter radar (operated in an ST mode) were simultaneously operated to compare vertical air motions in the troposphere and lower stratosphere. The two nearby radars were operated with their antennas pointed vertically with 750-m-range resolutions. The radars have widely differing operating frequencies (50 MHz and 1290 MHz); for the long-wavelength radar, returned signals are thought to result from combination of specular reflection and turbulence-scattered signals, with either mechanism possibly being dominant at various heights. The short-wavelength radar is expected to receive only turbulence-scattered signals. Both radars were able to detect motions of a few centimeters per second and detect the presence of similar short-period wave motions. However, when the data were averaged for an hour or more, significant differences in the averaged data were observed. We suggest that the differences are probably due to either experimental errors or apparent vertical motions observed with the Poker Flat radar as a result of off-vertical specular echoes from horizontally moving tilted layers. An estimate of an apparent antenna pointing direction of 0.27¿ off vertical has been made for the Poker Flat radar. With the available data we are unable to determine if this is a true antenna pointing error or the result of horizontally moving tilted layers on the specular echoing mechanism. At heights where specular echoes are dominant, the physical pointing direction of the antenna is not critical. The effective pointing angle of the antenna is determined by the normal to the specular reflection layer. In this case a component of the horizontal wind may be interpreted as a vertical wind component because small tilts in the atmosphereric layers control the effective antenna pointing direction. For the other heights where nonspecular scattering is dominant the physical pointing direction of the antenna is important; for vertically directed antennas, small pointing errors may cause a component of the horizontal wind to be interpreted as a vertical motion.