EKF: Use dead-reckoning status to determine if air data should modify non-wind states

EKF/airspeed_fusion.cpp

@@ -72,6 +72,9 @@ void Ekf::fuseAirspeed()
 
 	// Perform fusion of True Airspeed measurement
 	if (v_tas_pred > 1.0f) {
+		// determine if we need the sideslip fusion to correct states other than wind
+		bool update_wind_only = !_is_dead_reckoning;
+
 		// Calculate the observation jacobian
 		// intermediate variable from algebraic optimisation
 		SH_TAS[0] = 1.0f/v_tas_pred;
@@ -102,7 +105,7 @@ void Ekf::fuseAirspeed()
 
 		SK_TAS[1] = SH_TAS[1];
 
-		if (((_time_last_imu - _time_last_gps) < 1e6) || ((_time_last_imu - _time_last_ext_vision) < 1e6) || ((_time_last_imu - _time_last_optflow) < 1e6)) {
+		if (update_wind_only) {
 			// If we are getting aiding from other sources, then don't allow the airspeed measurements to affect the non-windspeed states
 			for (unsigned row = 0; row <= 21; row++) {
 				Kfusion[row] = 0.0f;