Pulsation signals detected in the E region ionospheric convection flow with the SABRE radar are described. Large amplitude oscillatory signals were detected, localized to a region of approximate dimension 300 km in the north-south direction and 100 km in the east-west direction. The spectral characteristics of the signals show the presence of linearly polarised waves propagating westward with an apparent horizontal phase speed of 8 km/s. The pulsations occur at a time when the background flow is changing and, in particular, are located next to a region where a sheet of high vertical vorticity develops. The oscillatory signal contains field-aligned current colocated with the vorticity in the background flow. Vertical current density is of order 10-6 Am-2. We propose that the pulsations are system transients excited in response to flow reconfiguration in the magnetosphere. We conclude by showing spacecraft data indicating magnetopause flux transfer event activity was occurring in the same local time sector at the same time of the events reported here. ¿ American Geophysical Union 1988