diff --git a/src/modules/ekf2/test/CMakeLists.txt b/src/modules/ekf2/test/CMakeLists.txt
index b2cfac70b0..2ade2e7509 100644
--- a/src/modules/ekf2/test/CMakeLists.txt
+++ b/src/modules/ekf2/test/CMakeLists.txt
@@ -50,4 +50,5 @@ px4_add_unit_gtest(SRC test_EKF_ringbuffer.cpp LINKLIBS ecl_EKF ecl_sensor_sim)
 px4_add_unit_gtest(SRC test_EKF_terrain_estimator.cpp LINKLIBS ecl_EKF ecl_sensor_sim)
 px4_add_unit_gtest(SRC test_EKF_utils.cpp LINKLIBS ecl_EKF ecl_sensor_sim)
 px4_add_unit_gtest(SRC test_EKF_withReplayData.cpp LINKLIBS ecl_EKF ecl_sensor_sim)
+px4_add_unit_gtest(SRC test_EKF_yaw_estimator.cpp LINKLIBS ecl_EKF ecl_sensor_sim ecl_test_helper)
 px4_add_unit_gtest(SRC test_SensorRangeFinder.cpp LINKLIBS ecl_EKF ecl_sensor_sim)
diff --git a/src/modules/ekf2/test/test_EKF_yaw_estimator.cpp b/src/modules/ekf2/test/test_EKF_yaw_estimator.cpp
new file mode 100644
index 0000000000..28e19b8f7a
--- /dev/null
+++ b/src/modules/ekf2/test/test_EKF_yaw_estimator.cpp
@@ -0,0 +1,117 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2021 ECL Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * Test the yaw estimator
+ * @author Mathieu Bresciani <mathieu@auterion.com>
+ */
+
+#include <gtest/gtest.h>
+#include "EKF/ekf.h"
+#include "sensor_simulator/sensor_simulator.h"
+#include "sensor_simulator/ekf_wrapper.h"
+#include "test_helper/reset_logging_checker.h"
+
+class EKFYawEstimatorTest : public ::testing::Test
+{
+public:
+
+	EKFYawEstimatorTest(): ::testing::Test(),
+		_ekf{std::make_shared<Ekf>()},
+		_sensor_simulator(_ekf),
+		_ekf_wrapper(_ekf) {};
+
+	std::shared_ptr<Ekf> _ekf;
+	SensorSimulator _sensor_simulator;
+	EkfWrapper _ekf_wrapper;
+
+	// Setup the Ekf with mag aiding disabled
+	void SetUp() override
+	{
+		_ekf->init(0);
+		_ekf_wrapper.setMagFuseTypeNone();
+		_sensor_simulator.runSeconds(2);
+		_ekf_wrapper.enableGpsFusion();
+		_sensor_simulator.startGps();
+		_sensor_simulator.runSeconds(11);
+	}
+
+	// Use this method to clean up any memory, network etc. after each test
+	void TearDown() override
+	{
+	}
+};
+
+TEST_F(EKFYawEstimatorTest, inAirYawAlignment)
+{
+	// GIVEN: an accelerating vehicle with unknown heading
+	EXPECT_EQ(1, (int) _ekf->control_status_flags().tilt_align);
+	EXPECT_EQ(0, (int) _ekf->control_status_flags().yaw_align);
+
+	const Vector3f accel_frd{1.0, -1.f, 0.f};
+	_sensor_simulator._imu.setAccelData(accel_frd + Vector3f(0.f, 0.f, -CONSTANTS_ONE_G));
+	const float dt = 0.5f;
+	const float yaw = math::radians(-30.f);
+	const Dcmf R_to_earth{Eulerf(0.f, 0.f, yaw)};
+
+	_ekf->set_in_air_status(true);
+	ResetLoggingChecker reset_logging_checker(_ekf);
+	reset_logging_checker.capturePreResetState();
+
+	// WHEN: GNSS velocity is available
+	Vector3f simulated_velocity{};
+
+	for (int i = 0; i < 10; i++) {
+		_sensor_simulator.runSeconds(dt);
+		simulated_velocity += R_to_earth * accel_frd * dt;
+		_sensor_simulator._gps.setVelocity(simulated_velocity);
+	}
+
+	// THEN: the heading can be estimated and then used to fuse GNSS vel and pos to the main EKF
+	float yaw_est{};
+	float yaw_est_var{};
+	float dummy[5];
+	_ekf->getDataEKFGSF(&yaw_est, &yaw_est_var, dummy, dummy, dummy, dummy);
+
+	const float tolerance_rad = math::radians(5.f);
+	EXPECT_NEAR(yaw_est, yaw, tolerance_rad);
+	EXPECT_LT(yaw_est_var, tolerance_rad);
+
+	// 2 resets: 1 after IMU+GNSS yaw alignment and 1 when starting GNSS aiding
+	reset_logging_checker.capturePostResetState();
+	EXPECT_TRUE(reset_logging_checker.isHorizontalVelocityResetCounterIncreasedBy(2));
+	EXPECT_TRUE(reset_logging_checker.isHorizontalPositionResetCounterIncreasedBy(2));
+
+	EXPECT_TRUE(_ekf->local_position_is_valid());
+	EXPECT_TRUE(_ekf->global_position_is_valid());
+}