In November 2001, the Equatorial Atmosphere Radar (0.20¿S, 100.32¿E) observed a continuous strong eastward wind shear (10--50 m s-1 km-1), westward wind (2--27 m s-1), and the radar echo layer tilted downward to the west in the region 0--1 km above the tropopause. During the same period, the Richardson number calculated with hourly-averaged horizontal wind and radiosonde temperature data was almost continuously <0.5 and sometimes <0.25, which seems to indicate that the Kelvin-Helmholtz instability (KHI) frequently occurs in that region. The existence of the tilted radar echo layer can be explained by KHI billows. A spurious updraft caused by the KHI-induced tilted echo layer and by the strong westward wind was also observed in the region.