Plain English Meaning
How a pilot's eyes — and the way the brain handles what they see — work together to spot other aircraft and judge what is happening around the airplane.
Full Definition
The human eye and the related processes by which a pilot detects, interprets, and responds to visual information in flight. In the collision avoidance context, it refers specifically to how a pilot uses sight to scan for traffic, judge distance and closure, and recognize hazards both inside and outside the cockpit.
Context Anchor
Seen in collision avoidance discussions, especially when learning how pilots see and avoid other aircraft.
Derivation
From Latin 'visus' (sight) and Greek 'systema' (an organized whole). Together: the organized way the takes in and processes what is seen — useful here because collision avoidance depends not just on the eye, but on how the brain interprets what the eye picks up.