Abstract: Disclosed is an apparatus for measuring the aerodynamic parameters of an airflow around an aircraft. A streamlined body is rotatably mounted in the airflow such that it aligns itself freely with the flow. Total and static pressure pick-off apertures are provided in the body. The measurement of the true angle of incidence is obtained from two distinct measurements. A first measurement mechanically provides the orientation .alpha.m of the streamlined body relative to the aircraft and the other provides the aerodynamic pressure orientation .alpha.a of the same streamlined body relative to the airflow. The true angle of incidence .alpha. is then determined by summing .alpha.m and .alpha.a.