[William Tell]

Theoria said: "It is still part of Army doctrine for active air defense measures. "

Is that right?

When I was in Army basic training in 1968 we were taught not to bother shooting at aircraft, and we were training with M-14s.

[Theoria]

You can see it here in FM 44-8[pdf]. Section, 5-4. Use against UAV's as well.

Some examples.