diff --git a/EKF/ekf.cpp b/EKF/ekf.cpp
index 9e7862ff83..4bac4bdd63 100644
--- a/EKF/ekf.cpp
+++ b/EKF/ekf.cpp
@@ -303,6 +303,15 @@ bool Ekf::update()
 
 		}
 
+		// If we are using external vision aiding and data has fallen behind the fusion time horizon then fuse it
+		if (_ext_vision_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_ev_sample_delayed)) {
+			// use external vision posiiton and height observations
+			if (_control_status.flags.ev_pos) {
+				_fuse_pos = true;
+				_fuse_height = true;
+			}
+		}
+
 		// If we are using optical flow aiding and data has fallen behind the fusion time horizon, then fuse it
 		if (_flow_buffer.pop_first_older_than(_imu_sample_delayed.time_us, &_flow_sample_delayed)
 		    && _control_status.flags.opt_flow && (_time_last_imu - _time_last_optflow) < 2e5
@@ -315,8 +324,6 @@ bool Ekf::update()
 		if (!_control_status.flags.gps && !_control_status.flags.opt_flow
 		    && ((_time_last_imu - _time_last_fake_gps > 2e5) || _fuse_height)) {
 			_fuse_pos = true;
-			_gps_sample_delayed.pos(0) = _last_known_posNE(0);
-			_gps_sample_delayed.pos(1) = _last_known_posNE(1);
 			_time_last_fake_gps = _time_last_imu;
 		}
 
diff --git a/EKF/vel_pos_fusion.cpp b/EKF/vel_pos_fusion.cpp
index 433b6eeb1a..c71e014b7d 100644
--- a/EKF/vel_pos_fusion.cpp
+++ b/EKF/vel_pos_fusion.cpp
@@ -83,24 +83,31 @@ void Ekf::fuseVelPosHeight()
 
 	if (_fuse_pos) {
 		fuse_map[3] = fuse_map[4] = true;
-		// horizontal position innovations
-		_vel_pos_innov[3] = _state.pos(0) - _gps_sample_delayed.pos(0);
-		_vel_pos_innov[4] = _state.pos(1) - _gps_sample_delayed.pos(1);
 
-		// observation variance - user parameter defined
-		// if we are in flight and not using GPS, then use a specific parameter
-		if (!_control_status.flags.gps) {
+		// Calculate innovations and observation variance depending on type of observations
+		// being used
+		if (!_control_status.flags.gps && !_control_status.flags.ev_pos) {
+			// No observations - use a static position to constrain drift
 			if (_control_status.flags.in_air) {
 				R[3] = fmaxf(_params.pos_noaid_noise, _params.gps_pos_noise);
 
 			} else {
 				R[3] = _params.gps_pos_noise;
 			}
+			_vel_pos_innov[3] = _state.pos(0) - _last_known_posNE(0);
+			_vel_pos_innov[4] = _state.pos(1) - _last_known_posNE(1);
 
-		} else {
+		} else if (_control_status.flags.gps) {
 			float lower_limit = fmaxf(_params.gps_pos_noise, 0.01f);
 			float upper_limit = fmaxf(_params.pos_noaid_noise, lower_limit);
 			R[3] = math::constrain(_gps_sample_delayed.hacc, lower_limit, upper_limit);
+			_vel_pos_innov[3] = _state.pos(0) - _gps_sample_delayed.pos(0);
+			_vel_pos_innov[4] = _state.pos(1) - _gps_sample_delayed.pos(1);
+
+		} else if (_control_status.flags.ev_pos) {
+			R[3] = fmaxf(_ev_sample_delayed.posErr, 0.01f);
+			_vel_pos_innov[3] = _state.pos(0) - _ev_sample_delayed.posNED(0);
+			_vel_pos_innov[4] = _state.pos(1) - _ev_sample_delayed.posNED(1);
 
 		}
 
@@ -145,6 +152,15 @@ void Ekf::fuseVelPosHeight()
 			R[5] = R[5] * R[5];
 			// innovation gate size
 			gate_size[5] = fmaxf(_params.range_innov_gate, 1.0f);
+		} else if (_control_status.flags.ev_pos) {
+			fuse_map[5] = true;
+			// calculate the innovation assuming the external vision observaton is in local NED frame
+			_vel_pos_innov[5] = _state.pos(2) - _ev_sample_delayed.posNED(2);
+			// observation variance - defined externally
+			R[5] = fmaxf(_ev_sample_delayed.posErr, 0.01f);
+			R[5] = R[5] * R[5];
+			// innovation gate size
+			gate_size[5] = fmaxf(_params.baro_innov_gate, 1.0f);
 		}
 
 	}