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.
Plain English
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.
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.