Plain English Meaning
A type of airport radar used by controllers near busy airports. It shows where aircraft are, how high they are, and where weather is, all on the same screen.
Full Definition
A specific model of terminal-area surveillance radar used by air traffic control facilities such as TRACONs to detect and track aircraft within roughly 60 nautical miles of an airport. The ASR-9 provides controllers with aircraft position, altitude (via the associated secondary radar), and weather information on a single display, and it serves as the primary radar tool for sequencing and separating aircraft in the terminal environment.
Context Anchor
You will see ASR-9 mentioned in discussions of TRACON facilities, radar services, and the equipment controllers use to handle traffic near airports.
Derivation
ASR stands for Airport Surveillance Radar. The '-9' simply identifies it as the ninth generation model in a family of FAA terminal radars. Knowing this helps the reader understand that ASR-9 is one specific piece of equipment, not a category or procedure.
Why Pilots Care
It supplies the position and altitude data controllers need to keep aircraft safely separated during approaches and departures.
Intuition Check
Do not read ASR-9 as a radio frequency, procedure, or approach clearance. It is ground-based radar equipment used by controllers, not an instruction for the pilot to fly.
Example Sentence 1
The TRACON controller used the ASR-9 to sequence arriving traffic onto the final approach course.
Example Sentence 2
When the ASR-9 went offline for maintenance, arrivals were delayed until backup radar was activated.