The conventional landing technique for most aircraft involves a constant speed approach along a well denned glidepath. The speed is selected to maintain an adequate margin above the stall. Allowance is made for wind conditions. At the beginning of the landing approach a pilot is quoted a nominal mean surface windspeed and direction by radio contact with the airfield control tower. The local controller is provided with a conventional meteorological office dial-reading anemometer but, because of other duties, does not monitor it continuously.