Definition
An operational requirement, primarily applied to drone (UAS) operations, that the remote pilot, or a designated visual observer, must be able to see the unmanned aircraft at all times with unaided vision (corrective lenses permitted, but no binoculars, telescopes, or first-person-view goggles). The pilot must be able to determine the aircraft's location, attitude, altitude, and direction of flight, and observe the surrounding airspace for other traffic or hazards.
Plain English
You must be able to see your drone with your own eyes the whole time it is flying. Glasses or contacts are fine, but you cannot rely on a camera feed, binoculars, or someone watching from far away.
Context Anchor
Seen in unmanned aircraft and drone operating rules, especially when deciding whether a flight can be conducted without special approval.
Derivation
Visual comes from the Latin idea of seeing. Line of sight means the straight path from your eyes to what you can see. Together, the term points to direct seeing, not seeing the aircraft only through a camera, screen, or map.
Why Pilots Care
Maintaining VLOS prevents loss of aircraft control and mid-air collisions; operations beyond VLOS require specific FAA authorization.
Intuition Check
VLOS does not mean the control signal still reaches the aircraft, and it does not mean you can see it on a screen. It means actual eye contact with the aircraft, good enough to know where it is and avoid hazards.
Example Sentence 1
The remote pilot kept the drone within VLOS throughout the inspection, never letting it drift behind the building.
Example Sentence 2
A pilot requested a waiver after determining the mission could not be completed under VLOS rules.