Plain English Meaning

Working out how far away something is by looking at it. At night this is much harder, so a light or object can appear closer or farther than it really is.

Full Definition

The pilot's judgment of how far away an object, terrain feature, or other aircraft is, based on visual cues such as size, brightness, perspective, and known reference points. At night, distance estimation becomes unreliable because most of the cues the eye normally uses are reduced or missing.

Context Anchor

Used in night flying, especially when judging runway position, traffic spacing, terrain, towers, or other lighted objects.