diff --git a/src/lib/tecs/TECS.cpp b/src/lib/tecs/TECS.cpp
index 7462dd84cc..8f79b874d7 100644
--- a/src/lib/tecs/TECS.cpp
+++ b/src/lib/tecs/TECS.cpp
@@ -55,8 +55,8 @@ static constexpr float DT_MAX = 1.0f;	///< max value of _dt allowed before a fil
  * inertial nav data is not available. It also calculates a true airspeed derivative
  * which is used by the airspeed complimentary filter.
  */
-void TECS::update_vehicle_state_estimates(float airspeed, const matrix::Dcmf &rotMat,
-		const matrix::Vector3f &accel_body, bool altitude_lock, bool in_air,
+void TECS::update_vehicle_state_estimates(float airspeed, const float speed_deriv_forward, bool altitude_lock,
+		bool in_air,
 		float altitude, float vz)
 {
 	// calculate the time lapsed since the last update
@@ -89,12 +89,8 @@ void TECS::update_vehicle_state_estimates(float airspeed, const matrix::Dcmf &ro
 
 	// Update and average speed rate of change if airspeed is being measured
 	if (PX4_ISFINITE(airspeed) && airspeed_sensor_enabled()) {
-		// Assuming the vehicle is flying X axis forward, use the X axis measured acceleration
-		// compensated for gravity to estimate the rate of change of speed
-		const float speed_deriv_raw = rotMat(2, 0) * CONSTANTS_ONE_G + accel_body(0);
-
 		// Apply some noise filtering
-		_TAS_rate_filter.update(speed_deriv_raw);
+		_TAS_rate_filter.update(speed_deriv_forward);
 		_speed_derivative = _TAS_rate_filter.getState();
 
 	} else {
diff --git a/src/lib/tecs/TECS.hpp b/src/lib/tecs/TECS.hpp
index 67fd70c70f..64de3b4f16 100644
--- a/src/lib/tecs/TECS.hpp
+++ b/src/lib/tecs/TECS.hpp
@@ -74,8 +74,7 @@ public:
 	 * Must be called prior to udating tecs control loops
 	 * Must be called at 50Hz or greater
 	 */
-	void update_vehicle_state_estimates(float airspeed, const matrix::Dcmf &rotMat,
-					    const matrix::Vector3f &accel_body, bool altitude_lock, bool in_air,
+	void update_vehicle_state_estimates(float airspeed, const float speed_deriv_forward, bool altitude_lock, bool in_air,
 					    float altitude, float vz);
 
 	/**
diff --git a/src/modules/fw_pos_control_l1/FixedwingPositionControl.cpp b/src/modules/fw_pos_control_l1/FixedwingPositionControl.cpp
index 1d9bed7df1..bddbaa776b 100644
--- a/src/modules/fw_pos_control_l1/FixedwingPositionControl.cpp
+++ b/src/modules/fw_pos_control_l1/FixedwingPositionControl.cpp
@@ -1852,15 +1852,17 @@ FixedwingPositionControl::tecs_update_pitch_throttle(const hrt_abstime &now, flo
 	/* Using tecs library */
 	float pitch_for_tecs = _pitch - radians(_param_fw_psp_off.get());
 
-	/* filter speed and altitude for controller */
-	Vector3f accel_body(_vehicle_acceleration_sub.get().xyz);
+	// calculate speed derivative in forward direction, which is used by complimentary filter to calculate filtered airspeed
+	Vector3f speed_deriv_body = _R_nb.transpose() * Vector3f(_local_pos.ax, _local_pos.ay, _local_pos.az);
+	float speed_deriv_forward;
 
 	// tailsitters use the multicopter frame as reference, in fixed wing
 	// we need to use the fixed wing frame
 	if (_vtol_tailsitter) {
-		float tmp = accel_body(0);
-		accel_body(0) = -accel_body(2);
-		accel_body(2) = tmp;
+		speed_deriv_forward = -speed_deriv_body(2);
+
+	} else {
+		speed_deriv_forward = speed_deriv_body(0);
 	}
 
 	/* tell TECS to update its state, but let it know when it cannot actually control the plane */
@@ -1871,8 +1873,7 @@ FixedwingPositionControl::tecs_update_pitch_throttle(const hrt_abstime &now, flo
 				    _control_mode.flag_control_altitude_enabled));
 
 	/* update TECS vehicle state estimates */
-	_tecs.update_vehicle_state_estimates(_airspeed, _R_nb,
-					     accel_body, (_local_pos.timestamp > 0), in_air_alt_control,
+	_tecs.update_vehicle_state_estimates(_airspeed, speed_deriv_forward, (_local_pos.timestamp > 0), in_air_alt_control,
 					     _current_altitude, _local_pos.vz);
 
 	/* scale throttle cruise by baro pressure */