The low airspeed system is calibrated (or perhaps characterized would be a better term) to account for the inflow effects. . .The way this characterization would be done is to fly the helicopter at different weights, in and out of ground effect using a pace vehicle to obtain exact airspeeds. This data is then fed into the computer to compare with what it saw, and make the system display the correct values of wind.. .It doesn't work particulary well when doing rapid transitions to and from the hover, but it is way better than nothing.. .We have one of these systems on our ex-Canadian Forces Bell 212 (it was a fully instrumented aircraft from the Canadian test center at Cold Lake)and it is very useful.