What does an ATC light signal of red on the ground mean?

A red light signal from Air Traffic Control (ATC) on the ground indicates that the pilot must stop their aircraft immediately. This signal is critical for ensuring safety in air traffic management, as it often signifies that there is a potential hazard or that the movement area is not clear for further progress.

When pilots see a red signal, they should quickly assess their situation and comply with the instruction to halt all movement. This is essential for avoiding potential collisions or accidents on the ground and for maintaining safe separation from other aircraft or vehicles. It reflects the necessity for immediate compliance with ground traffic instructions within controlled airspace.

Understanding light signals is a vital part of a pilot's training, ensuring they can safely navigate and respond to ground traffic management directives effectively.