Who notifies the control tower when a scramble is ordered?

The correct choice is the Air Defense Control Facility (ADCF), which plays a crucial role in military air operations, especially during critical situations like a scramble. When a scramble is ordered, it is the responsibility of the ADCF to communicate this order to ensure a timely and coordinated response from the fighter aircraft. The ADCF is specifically tasked with the command and control of air defense operations, making it their duty to relay critical information such as scramble notifications to the control tower.

In this context, each of the other options has different functions within military operations. Although the Flight Supervisor may oversee flight operations, they do not directly notify the control tower in the instance of a scramble. The Base Operations Center handles broader logistical and operational support and might be aware of the scramble, but the direct notification to the control tower is initiated by the ADCF. Air Traffic Control generally oversees civilian airspace within the realm of commercial aviation and is not involved in military scramble operations, thus they would not be the notifying entity in this scenario.