Definition
An unobstructed, direct view between two points, where the observer can see the object continuously with the unaided eye (corrective lenses permitted, but no binoculars, telescopes, or video links). In aviation, it most commonly refers to the regulatory requirement that the operator of a small unmanned aircraft (drone) keep the aircraft within their own direct visual sight throughout the entire flight.
Plain English
You can see it with your own eyes, in a straight line, with nothing blocking the view.
Context Anchor
Commonly used in drone operations, traffic scanning, and any operation where the pilot must keep direct visual contact with the aircraft.
Derivation
From Latin visualis (relating to sight) and the everyday phrase 'line of sight' — a straight, uninterrupted path from the eye to the object. 'Visual' is added to make clear the path must be seen with the eyes, not detected by camera, radar, or radio.
Why Pilots Care
Allows immediate detection of traffic, obstacles, or loss of control so corrective action can be taken before an incident occurs.
Intuition Check
Visual Line Of Sight does not mean the aircraft is visible on a screen or that you roughly know where it is. It means you can directly see the aircraft itself with your eyes well enough to manage the flight safely.
Example Sentence 1
Part 107 requires the remote pilot to keep the drone within visual line of sight at all times during the flight.
Example Sentence 2
If the aircraft flies behind a building, visual line of sight is lost and the flight must be adjusted immediately.