diff --git a/EKF/control.cpp b/EKF/control.cpp
index ac753e245f..2ea5692b0f 100644
--- a/EKF/control.cpp
+++ b/EKF/control.cpp
@@ -283,10 +283,9 @@ void Ekf::controlExternalVisionFusion()
 			_ev_sample_delayed.posNED(1) -= pos_offset_earth(1);
 			_ev_sample_delayed.posNED(2) -= pos_offset_earth(2);
 
-			// Use an incremental position fusion method for EV data if using GPS or if the observations are not in NED
-			if (_control_status.flags.gps || (_params.fusion_mode & MASK_ROTATE_EV)) {
+                        // Use an incremental position fusion method for EV position data if GPS is also used
+                        if (_params.fusion_mode & MASK_USE_GPS) {
 				_fuse_hpos_as_odom = true;
-
 			} else {
 				_fuse_hpos_as_odom = false;
 			}
@@ -301,15 +300,15 @@ void Ekf::controlExternalVisionFusion()
 					// calculate the change in position since the last measurement
 					Vector3f ev_delta_pos = _ev_sample_delayed.posNED - _pos_meas_prev;
 
-					// rotate measurement into body frame if required
-					if (_params.fusion_mode & MASK_ROTATE_EV) {
-						ev_delta_pos = _ev_rot_mat * ev_delta_pos;
-					}
+                                        // rotate measurement into body frame is required when fusing with GPS
+                                        ev_delta_pos = _ev_rot_mat * ev_delta_pos;
 
 					// use the change in position since the last measurement
 					_vel_pos_innov[3] = _state.pos(0) - _hpos_pred_prev(0) - ev_delta_pos(0);
 					_vel_pos_innov[4] = _state.pos(1) - _hpos_pred_prev(1) - ev_delta_pos(1);
 
+                                        // observation 1-STD error, incremental pos observation is expected to have more uncertainty
+                                        _posObsNoiseNE = fmaxf(_ev_sample_delayed.posErr, 0.5f);
 				}
 
 				// record observation and estimate for use next time
@@ -319,8 +318,14 @@ void Ekf::controlExternalVisionFusion()
 
 			} else {
 				// use the absolute position
-				_vel_pos_innov[3] = _state.pos(0) - _ev_sample_delayed.posNED(0);
-				_vel_pos_innov[4] = _state.pos(1) - _ev_sample_delayed.posNED(1);
+                                Vector3f ev_pos_meas = _ev_sample_delayed.posNED;
+                                if (_params.fusion_mode & MASK_ROTATE_EV) {
+                                        ev_pos_meas = _ev_rot_mat * ev_pos_meas;
+                                }
+                                _vel_pos_innov[3] = _state.pos(0) - ev_pos_meas(0);
+                                _vel_pos_innov[4] = _state.pos(1) - ev_pos_meas(1);
+                                // observation 1-STD error
+                                _posObsNoiseNE = fmaxf(_ev_sample_delayed.posErr, 0.01f);
 
 				// check if we have been deadreckoning too long
 				if ((_time_last_imu - _time_last_pos_fuse) > _params.reset_timeout_max) {