What measurements does the angle of attack (AOA) sensor provide?

The angle of attack (AOA) sensor is crucial for determining how an aircraft is performing in terms of its aerodynamic characteristics. Specifically, it measures the angle between the chord line of the wing and the direction of the oncoming airflow, which is essential for understanding the aircraft's lift and stall characteristics.

By providing the direction of airflow relative to the fuselage, the AOA sensor enables pilots and flight control systems to make informed decisions about airspeed management and aircraft handling, particularly during critical phases of flight such as takeoff and landing. This data is vital for ensuring optimal performance and safety of the aircraft.

The other options relate to different measurements that an aircraft's systems might provide but do not directly correlate with the function of the AOA sensor. For example, while speed, vertical speed, and altitude are important metrics, they are measured by different instruments and systems within the aircraft. Thus, the AOA sensor's specific function is to inform about the angle of attack, making the understanding of airflow relative to the fuselage its primary purpose.