Definition
A required system of high-intensity flashing or rotating lights on an aircraft, designed to make it visible to other aircraft in flight. The system consists of either a red rotating beacon, white flashing strobe lights, or both, mounted in positions that provide visibility from all angles around the aircraft.
Plain English
A set of bright flashing or rotating lights on the aircraft that help other pilots see it and avoid hitting it. They are turned on whenever the engine is running so the airplane stands out in the sky or on the ramp.
Context Anchor
You encounter this term during preflight, engine start, taxi, and aircraft lighting checks, especially when deciding which exterior lights should be on.
Derivation
From 'anti-' (against) + 'collision' (a crash between two moving objects). The name reflects the system's purpose: to prevent mid-air or ground collisions by making the aircraft conspicuous.
Why Pilots Care
These lights directly support the see-and-avoid principle and are mandated by regulation for night flight, reducing the risk of mid-air collisions and runway conflicts.
Intuition Check
Do not read “anti-collision” as meaning the lights prevent collisions by themselves. They do not steer or separate airplanes; they only make the airplane more visible so people can see and avoid it.
Example Sentence 1
Before starting the engine, the pilot turned on the anti-collision light system to alert anyone nearby on the ramp.
Example Sentence 2
During the daytime VFR flight, the anti-collision lights remained on to help a converging aircraft spot the plane from several miles away.