Definition
A system of high-intensity flashing or rotating lights on an aircraft, typically including a red rotating beacon and white strobe lights, designed to make the aircraft conspicuous to other pilots and ground personnel. Required by regulation for most aircraft operations, the anticollision light system must be operating any time the aircraft is in flight, and on the ground when the engine is running, except when the pilot determines the lights would create a safety hazard.
Plain English
Bright flashing lights on the aircraft that make it easy to see, helping other pilots and people on the ground spot it and avoid getting too close.
Context Anchor
Seen in aircraft electrical system discussions, exterior light checks, and before-start or taxi checklists.
Derivation
From 'anti-' (against) and 'collision' (a crash between two moving objects). The name states the purpose plainly: lights intended to prevent mid-air or ground collisions by making the aircraft visible.
Why Pilots Care
They are required equipment for night flights and form part of the aircraft's electrical load, directly affecting safety and regulatory compliance.
Intuition Check
Anticollision lights do not physically prevent a collision. They help prevent one by making the aircraft easier to notice.
Example Sentence 1
Before starting the engine, the pilot turned on the anticollision lights to alert anyone nearby that the propeller was about to spin.
Example Sentence 2
From several miles away, the flashing anticollision lights on the approaching aircraft were clearly visible against the dark sky.