File:Ppi scope.png

Summary
A typical radar plan position indicator (PPI). The circles and radial lines indicate range (distance) and azimuth (direction) respectively, and are fixed marks on the screen. The thicker azimuth line is the lubber line, indicating either north (on a fixed land radar) or current heading (on a craft). The center of the screen reflects the location of the radar antenna. White spots indicate objects which the radar signal has reflected back from, typically indicating either land or other craft.

The plan position indicator is the most common type of radar display.