Flashing red light gun signal When aircraft on the ground see this signal, they should taxi clear of the active runway. Ground vehicles and personnel should also move away from the runway or taxiway.

When an aircraft is on the ground and you see a flashing red light (known as the "Anti-Collision Beacon"), it is a vital safety signal for ground crew and other pilots. It primarily indicates that the aircraft's engines are either running or are about to be started. It also signals that the aircraft is "active" and may start moving or pushing back from the gate at any moment. Ground crew members are trained to never approach an aircraft or go near the engines while this light is flashing. The beacon lights are usually located on the top and bottom of the fuselage to ensure maximum visibility from all angles. In 2026, many newer planes use high-intensity LED beacons that are even easier to see in bright daylight or heavy rain. If you are a passenger looking out the window and see the red light start to flash, it’s a sure sign that your journey is about to begin, as the pilots have just received clearance to start the "Engine Start" or "Pushback" sequence.