Calibration

The airspeed sensor reading is automatically zeroed by the APM during initialisation, so it is good practice during windy conditions to place a loose fitting cover over the pitot tube that shields the front hole and the four small side holes from the wind. This cover should be fitted prior to power on and removed before flight. If you forget to do this, you can always place the cover and repeat the airspeed auto-zero using the Mission Planners PREFLIGHT_CALIBRATE => Do Action.

The airspeed reading scale factor is adjusted using the ARSPD_RATIO parameter. Plane has an automatic calibration function that will adjust the value of ARSPD_RATIO automatically provided the plane is flown with frequent direction changes. A normal model flying field circuit pattern or loiter will achieve the required direction changes, cross-country flying will not. To enable automatic airspeed sensor calibration, set the value of ARSPD_AUTOCAL to 1.