Narrative:

A B737 was cleared for the ILS runway 25L and descending out of about 11;000 when I observed a target about 2 miles north of him tracking the 24R localizer outbound descending out of 10;000. It was on a discrete code. It continued eastbound as I issued traffic. After they missed; another target popped up at about 28 miles east descending out of 10;400 and somewhat converging with the B737. I issued the traffic and they missed by about 1 mile. It was also a discrete code. I asked for the supervisor to come over and look while the same issue started to occur with a company B737; the next arrival to 25L about 7 miles in trail. The supervisor had me immediately switch to single sensor mode as the operations controller had told him that one of the san diego radar's had failed. Going to single sensor eliminated all of the false targets. Fusion; for all of its good qualities; has some glaring problems; among them the propensity to reflect targets or generate false targets. I have been through this situation of converging targets and pilots that are issued traffic alerts on false targets due to fusion; and it has to stop. We; as controllers are losing the trust of the pilots when we issue stuff; in a somewhat harried way that is false information. If I cannot trust the radar display; I think reverting to a system that actually works would be a better and safer call. Maybe sct has too many radar sensor inputs to make fusion truly workable. Whatever the answer is; it has to stop; it is not safe.

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Original NASA ASRS Text

Title: SCT Controller described several false target events claiming that the FUSION RADAR continually produces target that do not exist; lowering the confidence of the pilots receiving the false traffic information.

Narrative: A B737 was cleared for the ILS Runway 25L and descending out of about 11;000 when I observed a target about 2 miles north of him tracking the 24R localizer outbound descending out of 10;000. It was on a discrete code. It continued eastbound as I issued traffic. After they missed; another target popped up at about 28 miles east descending out of 10;400 and somewhat converging with the B737. I issued the traffic and they missed by about 1 mile. It was also a discrete code. I asked for the Supervisor to come over and look while the same issue started to occur with a company B737; the next arrival to 25L about 7 miles in trail. The Supervisor had me immediately switch to single sensor mode as the Operations Controller had told him that one of the San Diego RADAR's had failed. Going to single sensor eliminated all of the false targets. FUSION; for all of its good qualities; has some glaring problems; among them the propensity to reflect targets or generate false targets. I have been through this situation of converging targets and pilots that are issued traffic alerts on false targets due to FUSION; and it has to stop. We; as controllers are losing the trust of the pilots when we issue stuff; in a somewhat harried way that is false information. If I cannot trust the RADAR display; I think reverting to a system that actually works would be a better and safer call. Maybe SCT has too many RADAR sensor inputs to make FUSION truly workable. Whatever the answer is; it has to stop; it is not safe.

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.