Definition
An imaginary straight line extending from the pilot's eye to a specific reference point, used as a visual cue to maintain orientation, position, or alignment relative to that point. In eights-on-pylons, the lateral axis of the airplane is held on this line so that an extension of the wing appears to pivot on the chosen pylon.
Plain English
A straight, invisible line drawn from your eye to something you're looking at. In flying, you use this line as a reference — for example, keeping the wing pointed exactly at a spot on the ground.
Context Anchor
In eights on pylons, the pilot uses the line of sight to judge whether the selected ground point appears to stay in the correct position beside the airplane.
Derivation
A plain English phrase: the 'line' you 'see along.' The expression has been used since the 1700s to mean the direct visual path between an observer and an object. It helps in aviation because it captures exactly what's happening — the pilot is using the geometry of their own gaze as a flying reference.
Why Pilots Care
Keeping the pylon on the line of sight automatically places the aircraft at the correct pivotal altitude and produces a coordinated turn with no slip or skid.
Analogy
Think of an invisible string running from your eyes to the point you are watching. That string is your line of sight.
Grounding Statement
Picture looking straight down an invisible ruler from your eye through the pylon; if the pylon drifts forward or back along that ruler, altitude is wrong and bank must change.
Intuition Check
Line of sight does not mean the airplane is flying in a straight line. It means the straight visual path between your eyes and the object you are watching.
Example Sentence 1
The instructor told the student to hold the line of sight from the wingtip to the silo, adjusting altitude as needed to keep the pylon from drifting.
Example Sentence 2
When the pylon stayed steady on the line of sight throughout the turn, the maneuver was coordinated at the proper altitude.