What is the signal for "stop" on the ground?

The signal for "stop" on the ground is indicated by a steady red light. This signal is universally recognized in aviation as a directive for pilots and ground personnel to halt all operations and movements of the aircraft. The steady red light serves a critical safety function, preventing potential conflicts on the taxiway or runway.

Understanding this signal helps maintain order and safety at airports, where multiple aircraft and vehicles may be moving simultaneously. In contrast to other signals—such as steady green, which indicates that it is safe to go, or flashing lights that convey different actions—steady red is clear and unambiguous, making it a key signal for ground operations.