Denver center traffic management coordinator reported of a false target that looked like a near mid ...

Narrative:

It was low IFR conditions with snow and 1/2 mile tower visibility. I cleared aircraft X off of runway 34L via RNAV to brkem; the transition fix to the south. This procedure requires a left turn to the southwest. I then used a staggered departure time for aircraft Y off of 34R to the east. When aircraft X was clearly in his turn to the southwest; I cleared the next south gate departure off of runway 34L. When aircraft Y tagged up I was scanning my strips and the airport surface detection equipment (asde-X). When I looked at the stars display I was surprised and alarmed to see aircraft Y target turning west and closing fast on aircraft X. I stopped aircraft Y 's climb at 070; as aircraft X was climbing out of 072. I issued a traffic alert and assigned aircraft Y present heading. The targets merged showing only 300 feet separation about 4 miles west of the field.my controller in charge (controller in charge) was monitoring the frequency and told me it was a false target for aircraft Y who was really flying runway heading off of 34R. I then told aircraft Y traffic no factor and cleared him back on course with a continued climb.I thought I was witnessing a near midair collision. This was the scariest thing I have seen in my years. Nothing else is even close.please work on the radar/fusion to mitigate these occurrences. But also; if you can share the replay so that a target jump is more readily recognized.the false target does not show up on falcon.

Original NASA ASRS Text

Title: Denver Center Traffic Management Coordinator reported of a false target that looked like a Near Mid Air Collision. Controller stated it was the scariest thing he had seen and wanted someone to work on the RADAR/FUSION problem.

Narrative: It was low IFR conditions with snow and 1/2 mile tower VIS. I cleared Aircraft X off of Runway 34L via RNAV to BRKEM; the transition fix to the south. This procedure requires a left turn to the southwest. I then used a staggered departure time for Aircraft Y off of 34R to the east. When Aircraft X was clearly in his turn to the southwest; I cleared the next south gate departure off of Runway 34L. When Aircraft Y tagged up I was scanning my strips and the Airport Surface Detection Equipment (ASDE-X). When I looked at the STARS display I was surprised and alarmed to see Aircraft Y target turning west and closing fast on Aircraft X. I stopped Aircraft Y 's climb at 070; as Aircraft X was climbing out of 072. I issued a Traffic Alert and assigned Aircraft Y present heading. The targets merged showing only 300 feet separation about 4 miles west of the field.My Controller in Charge (CIC) was monitoring the frequency and told me it was a false target for Aircraft Y who was really flying Runway heading off of 34R. I then told Aircraft Y traffic no factor and cleared him back on course with a continued climb.I thought I was witnessing a NMAC. This was the scariest thing I have seen in my years. Nothing else is even close.Please work on the Radar/Fusion to mitigate these occurrences. But also; if you can share the replay so that a target jump is more readily recognized.The false target does not show up on FALCON.

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	1408457
Time
Date	201612
Local Time Of Day	1801-2400
Place
Locale Reference	DEN.Airport
State Reference	CO
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Initial Climb
Flight Plan	IFR
Aircraft 2
Make Model Name	Medium Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Initial Climb
Flight Plan	IFR
Person 1
Function	Enroute Traffic Management
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Denver center traffic management coordinator reported of a false target that looked like a near mid air collision. Controller stated it was the scariest thing he had seen and wanted someone to work on the radar/fusion problem.