Sct controller described a near loss of MVA required standards; the reporter claiming the 'fusion' r...

Narrative:

A PA28 was on a base turn heading 140 degrees; 5 miles behind (increasing) a faster C182. All of a sudden isr showed on the radar (increased separation required) and the target started tracking right at the lead aircraft now showing a good altitude (3;400) and 190 KTS. Instant loss of separation; I turned the PA28 further away heading 120 because of where the radar showed him. All of a sudden the PA28 target jumped back to where it should have been; 1.5 miles east; heading through the final; towards higher terrain. I turned him back to the final. Separation was never really lost; even though the radar said it was; and the radar equipment completely erroneous target and tracking caused me to turn this aircraft into a more dangerous position. Fusion run without its closest sensor working is not reliable.

Original NASA ASRS Text

Title: SCT Controller described a near loss of MVA required standards; the reporter claiming the 'Fusion' RADAR system provided erroneous information regarding separation; prompting a turn which caused the event.

Narrative: A PA28 was on a base turn heading 140 degrees; 5 miles behind (increasing) a faster C182. All of a sudden ISR showed on the RADAR (increased separation required) and the target started tracking right at the lead aircraft now showing a good altitude (3;400) and 190 KTS. Instant loss of separation; I turned the PA28 further away heading 120 because of where the RADAR showed him. All of a sudden the PA28 target jumped back to where it should have been; 1.5 miles east; heading through the final; towards higher terrain. I turned him back to the final. Separation was never really lost; even though the RADAR said it was; and the RADAR equipment completely erroneous target and tracking caused me to turn this aircraft into a more dangerous position. Fusion run without its closest sensor working is not reliable.

Data retrieved from NASA's ASRS site as of July 2013 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	1036437
Time
Date	201209
Local Time Of Day	1801-2400
Place
Locale Reference	SCT.TRACON
State Reference	CA
Aircraft 1
Make Model Name	PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Person 1
Function	Approach Departure
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types

Sct controller described a near loss of MVA required standards; the reporter claiming the 'fusion' radar system provided erroneous information regarding separation; prompting a turn which caused the event.