Narrative:

Va approaches in use. Runway 28 left/right in use. Aircraft X requests an ILS runway 28R approach; not familiar with pdx. Multiple jet arrivals mixed in. Aircraft X was cleared for approach. About 6 or 7 miles in trail of aircraft X was an air carrier on a visual approach to runway 28L. The air carrier is over 200 knots ground speed. Aircraft X is about 90 knots over ground. We just started working on fusion radar about 6 days ago. New system for us. Totally different than single site radar. Anyway; when aircraft X was about over the FAF I noticed his track was tracking south. It did this for about 4 or five updates; then he was on the runway 28L final approach course with the air carrier right behind him with a hundred knot overtake. The tower was talking to aircraft X. I called traffic to the air carrier; called the tower to find out what aircraft X was doing; and about to cancel approach clearance to the air carrier when aircraft X's target jumped back on the ry 28R final. Over a half mile target jump. I watched it; everything looked good and I shipped the air carrier to tower. This scared me. I am going to further investigate this with qa. I believe aircraft X never left the runway 28R localizer and fusion was screwing up and not working. I need to see a replay on actual radar; single site. It was such a big target jump. But I don't know. Aircraft X could have drifted south of course; but to the other localizer course the back in one or two updates. We need to find out whether this was a fusion issue or if aircraft X actually flew what I saw.

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Original NASA ASRS Text

Title: P80 Controller describes a large jump of an aircraft on final; possibly caused by fusion radar.

Narrative: VA approaches in use. RWY 28 L/R in use. Aircraft X requests an ILS RWY 28R approach; not familiar with PDX. Multiple jet arrivals mixed in. Aircraft X was cleared for approach. About 6 or 7 miles in trail of Aircraft X was an air carrier on a visual approach to RWY 28L. The air carrier is over 200 knots ground speed. Aircraft X is about 90 knots over ground. We just started working on FUSION radar about 6 days ago. New system for us. Totally different than single site radar. Anyway; when Aircraft X was about over the FAF I noticed his track was tracking south. It did this for about 4 or five updates; then he was on the RWY 28L final approach course with the air carrier right behind him with a hundred knot overtake. The Tower was talking to Aircraft X. I called traffic to the air carrier; called the Tower to find out what Aircraft X was doing; and about to cancel approach clearance to the air carrier when Aircraft X's target jumped back on the RY 28R final. Over a half mile target jump. I watched it; everything looked good and I shipped the air carrier to Tower. This scared me. I am going to further investigate this with QA. I believe Aircraft X never left the RWY 28R localizer and Fusion was screwing up and not working. I need to see a replay on actual RADAR; single site. It was such a big target jump. But I don't know. Aircraft X could have drifted south of course; but to the other localizer course the back in one or two updates. We need to find out whether this was a Fusion issue or if Aircraft X actually flew what I saw.

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.