What type of signal is used to indicate “stop” to ramp vehicles?

The use of a red light or flag is standard in aviation and ramp operations to signal “stop.” This is a widely recognized visual cue that is consistent across various forms of transportation and within airport environments, ensuring that all personnel and vehicle operators understand the need to halt immediately when they see this signal. The red signal effectively communicates urgency and is critical in maintaining safety on the ramp, especially in areas with high traffic or potential hazards.

In contrast, other signals such as green lights suggest go or proceed, yellow lights indicate caution or prepare to stop, and blue lights are typically used for specific purposes that do not convey the stop command. Hence, the use of a red light or flag serves as a clear and universally acknowledged signal to prevent accidents and ensure the smooth operation of ramp activities.