The angle of attack vane swivels freely so anytime there is a significant airflow over it it will weathervane into it. It hangs limp (!) when the aircraft is sitting on the apron. During the take off roll it gradually tilts parallel to the relative wind where it remains until the aircraft slows down after landing. For all other phases of flight think of the difference between body angle and relative airflow and that's were the vane is pointing.