Final answer:
The fueling control valve on the Type IV hydrant system is opened to allow fuel to flow through the system during hot refueling operations.
Step-by-step explanation:
The fueling control valve on the Type IV hydrant system is opened to perform hot refueling operations by allowing fuel to flow through the system.
During hot refueling, fuel is transferred directly from the fuel truck to the aircraft while the aircraft's engines are running. This requires the fueling control valve to be opened so that fuel can flow through the system and reach the aircraft's fuel tanks.
By opening the fueling control valve, the flow of fuel is regulated and directed to the appropriate fueling points on the aircraft, ensuring a controlled and efficient process.