diff --git a/EKF/control.cpp b/EKF/control.cpp
index 6a53301c5f..da72eb8eb6 100644
--- a/EKF/control.cpp
+++ b/EKF/control.cpp
@@ -112,12 +112,12 @@ void Ekf::controlFusionModes()
 
 		} else {
 			if (_control_status.flags.in_air) {
-				// if transitioning from a non-3D fusion mode, we need to initialise the yaw angle and field states
+				// if transitioning into 3-axis fusion mode, we need to initialise the yaw angle and field states
 				if (!_control_status.flags.mag_3D) {
 					_control_status.flags.yaw_align = resetMagHeading(_mag_sample_delayed.mag);
 				}
 
-				// always use 3D mag fusion when airborne
+				// use 3D mag fusion when airborne
 				_control_status.flags.mag_hdg = false;
 				_control_status.flags.mag_2D = false;
 				_control_status.flags.mag_3D = true;
@@ -143,7 +143,7 @@ void Ekf::controlFusionModes()
 		_control_status.flags.mag_3D = false;
 
 	} else if (_params.mag_fusion_type == MAG_FUSE_TYPE_3D) {
-		// if transitioning from a non-3D fusion mode, we need to initialise the yaw angle and field states
+		// if transitioning into 3-axis fusion mode, we need to initialise the yaw angle and field states
 		if (!_control_status.flags.mag_3D) {
 			_control_status.flags.yaw_align = resetMagHeading(_mag_sample_delayed.mag);
 		}
diff --git a/EKF/ekf.cpp b/EKF/ekf.cpp
index 578dd20669..5441c8a082 100644
--- a/EKF/ekf.cpp
+++ b/EKF/ekf.cpp
@@ -115,11 +115,11 @@ bool Ekf::init(uint64_t timestamp)
 	_output_new.vel.setZero();
 	_output_new.pos.setZero();
 	_output_new.quat_nominal = matrix::Quaternion<float>();
-    
+
 	_delta_angle_corr.setZero();
 	_delta_vel_corr.setZero();
 	_vel_corr.setZero();
-    
+
 	_imu_down_sampled.delta_ang.setZero();
 	_imu_down_sampled.delta_vel.setZero();
 	_imu_down_sampled.delta_ang_dt = 0.0f;
@@ -180,6 +180,7 @@ bool Ekf::update()
 			fuseMag2D();
 
 		} else if (_control_status.flags.mag_hdg && _control_status.flags.yaw_align) {
+			// fusion of a Euler yaw angle from either a 321 or 312 rotation sequence
 			fuseHeading();
 
 		} else {
diff --git a/EKF/ekf.h b/EKF/ekf.h
index f11682878d..38b0cfe716 100644
--- a/EKF/ekf.h
+++ b/EKF/ekf.h
@@ -187,7 +187,7 @@ private:
 	// ekf sequential fusion of magnetometer measurements
 	void fuseMag();
 
-	// fuse heading measurement (currently uses estimate from magnetometer)
+	// fuse the first euler angle from either a 321 or 312 rotation sequence as the observation (currently measures yaw using the magnetometer)
 	void fuseHeading();
 
 	// fuse projecton of magnetometer onto horizontal plane