Definition
A radar display that shows targets as bright spots on a circular screen, with the radar antenna at the center. Range is shown by distance from the center, and direction is shown by the angle around the screen, giving a top-down map-like view of what the radar sees.
Plain English
A round radar screen that shows what is around the aircraft from above, like looking down at a map. Things farther from the center are farther away, and the position on the screen tells you which direction they are in.
Context Anchor
Seen in radar equipment discussions, especially weather radar, surveillance radar, and maintenance descriptions of radar displays.
Derivation
Plan' here means a top-down view, as in an architect's floor plan, not a schedule or intention. 'Position indicator' simply means it shows where things are. Together: a display that shows the position of objects as if viewed from directly above.
Why Pilots Care
Gives pilots a clear picture of surrounding traffic, weather returns, or terrain for better situational awareness during flight.
Analogy
Think of it like a map centered on your aircraft. Objects farther from the center are farther away, and their place around the circle shows the direction to look.
Intuition Check
“Plan” does not mean a flight plan or a future intention here. It means a top-down map-style view.
Example Sentence 1
The pilot scanned the PPI and saw a strong weather return about 20 miles ahead and slightly to the right.
Example Sentence 2
During preflight the pilot scanned the PPI for any storm cells in the departure path.