You can set the correction coefficient in percent by selecting a corresponding value in the “Value” menu item. In this menu item, 100 value corresponds to airspeed values got via the pitot tube. Values less than 100 decrease speed value by a coefficient equal to 100/”Value”. Values more than 100 increase it.
Also, you can set the correction coefficient on the basis of ground speed by selecting the “Set per current GPS groundspeed” menu item in “Airspeed Correction” menu. This operation must be performed during flight and in the absence of wind so that the aircraft ground and airspeed were equal.