plan position indicator

noun

1. a radarscope on which an object reflecting radar waves shows its bearing and distance from the radar detector by causing a spot of light to appear on a screen that represents a map of the area around the detector. : PPI

Word History and Origins

Origin of plan position indicator¹

First recorded in 1940–45

Example Sentences

The most common type, the "Plan Position Indicator," is a circular dial with an electronic beam like a minute hand, which sweeps around the dial in synchronization with the scanning antenna, painting in its fluorescent wake a picture of what radar sees.

From Time Magazine Archive