SPD Flag (amber) means the computed airspeed indication is inoperative. Instrument SPD and ALT flags appear on PFD The left SMYD, with information provided from the left AOA sensor, will activate the captain’s stick shaker based on a number of factors, including an excessive angle of attack as measured by the AOA sensor. The Stall Management Yaw Damper (SMYD) uses the information from the other resolver to calculate and send commands to the Stall Warning System. So the data from the left-side AOA sensor is processed and passed on by the left side ADIRU to the captain’s flight displays. The Air Data Inertial Reference Unit combines and measures various information to provide inertial position and track data, as well as attitude, altitude and airspeed data, to the flight deck displays.

One resolver is connected to the Air Data Inertial Reference Unit (ADIRU) computer for its side (left or right) and the second resolver is connected to the respective Stall Management Yaw Damper (SMYD). The vanes then provide the measured angle of the direction of the airflow relative to the fuselage. The vane is connected to two internal resolvers, each of which independently measures the rotation angle. The key external component of the AOA sensor installed on the Boeing 737 MAX is a vane which rotates to align with the airflow. In basic terms, the angle of attack allows us to understand the amount of lift the wing is generating. The Boeing 737-8 (MAX) has two independent angle of attack (AOA) sensors which are installed just behind the nose on either side of the aircraft. Now I’d like to look at that sensor and piece together what happened.

Previously, I stepped through the maintenance of the aircraft registered PK-LQP, which was destroyed in the crash of Lion Air flight 610 on the 29th of October 2018.įrom that post, it is clear that the aircraft was released back into service with a faulty AOA sensor on the left (Captain’s) side.

Angle of attack 737 torrent