Before diverting, to whom should the pilot notify their intention?

The correct choice is to notify the controlling agency before diverting. This is essential for several reasons. The controlling agency is responsible for managing air traffic and ensuring safe and efficient operations in the airspace. By informing them of the intention to divert, the pilot allows the agency to update their flight plan and coordinate with other aircraft in the vicinity. This communication is crucial for maintaining situational awareness and ensuring that other flights are aware of the change, which helps prevent potential conflicts.

In contrast, while notifying a flight lead, maintenance crew, or SOF may be necessary in specific situations or for coordination, the immediate requirement before initiating a diversion is to inform the controlling agency. This prioritization is rooted in air traffic management principles and safety protocols, emphasizing the need for communication with those tasked with maintaining the order and safety of the airspace.