Definition
A high-intensity flashing or rotating light installed on an aircraft to make it visible to other aircraft and reduce the risk of midair collision. Anticollision lights are typically red or white, may be strobes or rotating beacons, and are required to be operating whenever the aircraft engine is running, with limited exceptions when the pilot determines they would be detrimental to safety.
Plain English
A bright flashing light on an aircraft that helps other pilots see it and avoid hitting it.
Context Anchor
You encounter this term during preflight checks, exterior lighting discussions, and before engine start, taxi, takeoff, and flight.
Derivation
From 'anti' (against) and 'collision' (a crash between two moving objects). The name simply states the purpose: a light fitted against the possibility of a collision.
Why Pilots Care
These lights improve safety by making the aircraft visible to others and are required for night operations.
Intuition Check
Do not think of an anticollision light as a headlight for the pilot to see ahead. Its main job is to help other people see the aircraft.
Example Sentence 1
Before starting the engine, the pilot switched on the anticollision light to alert anyone near the aircraft.
Example Sentence 2
Anticollision lights on the wings and vertical stabilizer help other traffic see the airplane during low-visibility approaches.