thx guys
your comments are so meaningful
but in most aerodynamics books like "principles of helicopter flight", the most dangerous areas are from 330 deg to 210 deg from the nose and can lead to tail rotor vortex ring state which is similar to the main rotor vortex ring state, and in other way a full loss of tail rotor effectiveness. And this discussion regardless of the vertical fin.
In several mountains flights, we can't terminate our approach head wind, we have to put the wind a little bit to the right or left.