Which light gun signal indicates that a vehicle should clear the active runway?

Answer: B — Flashing red light

The flashing red light signal is used to communicate that a vehicle must immediately clear the active runway. This signal is crucial for maintaining airfield safety and ensuring that aircraft can safely land and take off without any obstructions on the runway. When the flashing red light is displayed, it serves as an urgent request for the vehicle operators to quickly vacate the runway area and avoid any potential hazards. In contrast, other light signals convey different messages. For example, a steady green light indicates that it is safe for the vehicle to proceed or enter the runway, while a steady red light signals that the vehicle must stop. A flashing white light is typically used as a signal for vehicles to return to the starting point or their original location, but it does not pertain to the immediate need to clear the active runway. Understanding these signals is essential for anyone operating a vehicle on or near an airfield to ensure safety and efficiency in air traffic operations.