We report here a case study of simultaneous observations from Geotail in the mid-tail region and from ground CANOPUS stations to determine the auroral electrojet activity associated with the detection of fast plasma flows in the magnetotail. Ground observations from the meridian scanning photometers indicate the occurrence of a detached auroral feature in association with a transient fast plasma flow in the mid-tail. Ground magnetometer observations suggest that the detached auroral feature and the transient fast flow in the mid-tail correspond to a new segment of the auroral electrojet (probably limited in the east-west extent) moving equatorward, with the original electro-jet anchoring at the poleward boundary of the auroral bulge. Based on this result, we propose a possible resolution to the controversy on whether or not transient fast flows in the tail or north-south auroral structures are substorm features. ¿ 2000 American Geophysical Union