Update libraries/SITL/SIM_JSON.cpp

Co-authored-by: Peter Hall <[email protected]>

libraries/SITL/SIM_JSON.cpp

@@ -331,7 +331,7 @@ void JSON::recv_fdm(const struct sitl_input &input)
         velocity_air_ef = velocity_ef - wind_ef;
 
         // velocity relative to airmass in body frame
-        velocity_air_bf = dcm.transposed() * velocity_ef;
+        velocity_air_bf = dcm.transposed() * velocity_air_ef;
 
         // airspeed
         airspeed = velocity_air_bf.length();