Which rotary-wing attack tactic is delivered while the aircraft is at altitude and in descending forward flight?

Diving Fire is the correct answer as it refers to a tactical technique employed by rotary-wing aircraft in which the helicopter descends while moving forward, allowing it to engage targets with increased accuracy and effectiveness. This tactic capitalizes on altitude to build speed and allows for the aircraft to present a smaller profile to enemy fire while delivering ordnance from a height.

The unique advantage of Diving Fire is that it enables the aircraft to maintain a certain level of speed, which is essential for evading enemy defenses and minimizing exposure to ground threats. By descending at an angle, the aircraft can effectively manage its altitude while remaining aerially dynamic, which is critical in a combat environment.

This method contrasts with Hovering Fire, where the aircraft remains stationary and typically at a lower altitude, exposing it to greater risk from enemy fire. Running Fire, on the other hand, involves a forward flight at a relatively constant altitude, usually without a descent involved, which does not match the description provided in the question.

Therefore, the characteristics of Diving Fire align perfectly with the criteria of the question, making it the appropriate choice.