Definition
A visual depth cue in which objects appear shorter or compressed along the line of sight as their distance from the observer increases. In flight, it causes runways, terrain features, and other landmarks to look squashed or flattened when viewed from far away or at a shallow angle, and to lengthen as the pilot gets closer or views them more directly.
Plain English
When you look at something from far away or at a low angle, it looks shorter than it really is. As you get closer, it stretches out to its true length. Pilots use this stretching and shrinking effect to judge distance.
Context Anchor
Seen in distance-estimation and depth-perception discussions, especially when judging runway length, spacing, or surface shape from the cockpit.
Derivation
From 'fore' (front) and 'shorten.' Foreshortening literally means 'shortening of the front.' It comes from art and drawing, where a tilted object appears shorter along its length than it actually is. The word 'apparent' is added because the object is not really shorter -- it only looks that way to the eye.
Why Pilots Care
It can cause pilots to misjudge runway length or touchdown point, increasing the chance of landing short or long.
Analogy
A long table looks much shorter when you stand at one end and look along its length than when you stand beside it. The table did not change; your viewing angle changed.
Grounding Statement
The object is the same size, but the part stretching away from you looks compressed because of the angle you are viewing it from.
Intuition Check
Apparent foreshortening does not mean the object is actually shorter. It means the object only looks shorter from your viewing angle.
Example Sentence 1
On a long straight-in approach, apparent foreshortening made the runway look like a small rectangle until the final mile, when it began to stretch out to its full length.
Example Sentence 2
On short final the runway showed strong apparent foreshortening, yet the pilot continued the stabilized approach.