Most of the "issues" trace back to the Army Black Hawk Copter: (1) Only 3 people were manning the copter. (Minimum 4 people mandated to fly the copter. (2 Piloting + 2 Viewing the (R) & (L) sides of the copter), (2) Copter was flying at roughly 400 ft, (Max permissible = 200 ft), (3) Copter deviated from flight path.
Regarding the Control Tower, it was: (1) Undermanned by roughly 30%. and, (2) Air Traffic Controller communicative skills were abysmal. Roughly 30 seconds prior to the midair collision, the Black Hawk Copter was instructed by the air traffic controller to, "pass behind the plane". How if the copter is headed in a Southerly direction does it "pass behind" a plane headed in a Northerly direction?