Sct TRACON controller reported observing a false radar target on a conflicting heading with traffic ...

Narrative:

I was working a busy simultaneous approach session. I had a full downwind of airplanes all slowed to 170 knots to maintain spacing and keep them inside my airspace boundary. During my scan; I notice a handoff from the eastern side of my airspace. At first; I panicked thinking the aircraft was heading right into my downwind and called traffic to the emb 175 multiple times. The pilot said he saw nothing and was looking. The target then took a sharp turn towards the emb 175 and fell off the scope. I don't recall what I said to the emb 175; other than it was believed to be a false target. I continued working the final until my break and went to see a replay to determine it was in fact a false target. The false targets showing up on the radar display is a dangerous operation. I keep thinking one of these days a believed false target will be a real one. I'm not sure the solution other than moving radar sites or turning off the fusion radar.

Original NASA ASRS Text

Title: SCT TRACON Controller reported observing a false radar target on a conflicting heading with traffic they were vectoring for an approach.

Narrative: I was working a busy simultaneous approach session. I had a full downwind of airplanes all slowed to 170 knots to maintain spacing and keep them inside my airspace boundary. During my scan; I notice a handoff from the eastern side of my airspace. At first; I panicked thinking the aircraft was heading right into my downwind and called traffic to the EMB 175 multiple times. The pilot said he saw nothing and was looking. The target then took a sharp turn towards the EMB 175 and fell off the scope. I don't recall what I said to the EMB 175; other than it was believed to be a false target. I continued working the final until my break and went to see a replay to determine it was in fact a false target. The false targets showing up on the radar display is a dangerous operation. I keep thinking one of these days a believed false target will be a real one. I'm not sure the solution other than moving radar sites or turning off the Fusion radar.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1513344
Time
Date	201801
Local Time Of Day	1801-2400
Place
Locale Reference	SCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	EMB ERJ 170/175 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 5
Events
Anomaly	ATC Issue All Types Inflight Event / Encounter Other / Unknown

Sct TRACON controller reported observing a false radar target on a conflicting heading with traffic they were vectoring for an approach.