VHF radar at Gadanki (13.5¿N, 79.2¿E) was operated continuously for 24 hours to obtain a unique set of high resolution (150 m in height and 2.5 min. in time) wind data in the troposphere and lower stratosphere. This high quality wind data have been used to estimate momentum flux of short period (<2 hr) wind fluctuations and the associated uncertainties. Error analysis has been carried out by varying the length of integration time. We show that an optimal time of averaging of about 15--16 hrs minimizes the error at a value nearly equal to the irreducible error observed by an ideal anemometer measuring u, v and w at a point.