What is a Line of Position (LOP) and how are multiple LOPs used to fix a position without a GPS fix?

• A. LOP is a circle around a known point; intersecting multiple circles fixes position.
• B. LOP is a line along which the true position lies; intersecting two or more LOPs yields the unknown position.
• C. LOP is the distance to a beacon.
• D. LOP cannot be used without a GPS fix.

Answer: (C)

A Line of Position is a line on the chart along which your true location must lie, derived from a single navigational observation relative to a known reference such as a beacon, landmark, or celestial body. One observation only narrows you to a line, not a single point, so you don’t know exactly where on that line you are. By taking two independent observations, you obtain two lines; the point where those lines intersect is your position. Using additional, independent lines provides cross-checks and improves accuracy, allowing you to fix your location without GPS.

Why distance to a beacon isn’t the right idea for a Line of Position: measuring distance alone places you somewhere on a circle centered on the beacon, not along a specific line. So that description doesn’t define a Line of Position. With multiple LOPs, you rely on the geometry of intersecting lines to pinpoint your location.