Final answer:
A flashing red light from a control tower directs an aircraft to taxi clear of the runway in use. It serves as a safety measure to manage traffic and prevent runway interference.
Step-by-step explanation:
On the ground, a flashing red light from the control tower is a signal to aircraft personnel. In the context of aviation, different light signals mean different things. Notably, a flashing red light indicates that the aircraft should taxi clear of the runway in use. This signal serves as a warning to pilots that the runway cannot be used for takeoff or landing, and they need to remain clear to avoid interference with other aircraft or ground traffic. In general aviation, understanding these signals is crucial for maintaining safety and managing traffic densities on busy airfields.