Which signal advises an aircraft to exercise extreme caution on the ground?

The signal that advises an aircraft to exercise extreme caution on the ground is the alternating red and green light. This signal indicates that the aircraft should be particularly vigilant and ready to respond to unexpected conditions or hazards. The alternating colors convey a warning that conditions may not be safe for normal operations, alerting pilots to be more observant and cautious about their surroundings, especially in busy or complex environments.

In air traffic control, understanding these signals is crucial for maintaining safety and ensuring that aircraft operate effectively within the airport environment. Being familiar with the meanings of different signals allows pilots to react appropriately and take necessary precautions while taxiing or maneuvering on the ground.