Narrative:

I was working the navajo departure sector; which is the north departure sector at P50. Navajo has pre-arranged coordination airspace the with apache feeder sector. Aircraft X departed phx on the ZEPER1 SID climbing to 8;000. I radar identified aircraft X and climbed the aircraft to 9;000 observing there were aircraft in the EAGUL6 STAR arrival corridor descending to 10;000. When aircraft X was approaching sprky; I observed a large gap between aircraft Z (A320) and aircraft Y (A321) in which with vectors I could continue aircraft X's climb. After passing sprky I issued a heading of 030 to aircraft X to allow them to be in a position to where I could keep the climb going with just a few more small vectors. I climbed aircraft X to FL210 and subsequently turned them to a heading of 350 where it would fall 3 miles behind aircraft Z but approximately 5 miles in front of aircraft Y. After issuing the turn to heading 350; scanning for other traffic; and talking to another aircraft; I returned my scan to verify aircraft X made the turn. I observed aircraft X had made a turn to what I thought was approximately a 335 heading which was now putting aircraft X too close to aircraft Z. I needed aircraft X on a heading of 350 so I told aircraft X to turn 15 degrees right short vector for traffic (trying to get aircraft X back on a 350 heading). It was my intention to keep aircraft X on a 350 heading until they passed/diverged with aircraft Z to which I could then turn aircraft X to a heading of 300 to pass behind aircraft Z (but well in front of aircraft Y).in hindsight; I think what happened was that I think I observed a false return of aircraft X on a 335 heading due to fusion stitching and that aircraft X was most likely on a 350 heading as assigned. When I assigned a 15 degree right turn to aircraft X; they probably turned to a 005 heading which was less than 3 miles in front of aircraft Y. Once I realized that aircraft X was in a position and heading that was not intended; I turned aircraft X to heading 300 attempting recovery and to get them to pass and diverge in front of aircraft Y's flight path. Aircraft X delayed the turn after correctly reading back the heading and then confirmed the heading of 300. I told aircraft X affirmative fly heading 300 immediately (in order to get the aircraft to turn in front of aircraft Y). [I then] issued the A321 traffic to aircraft X. Aircraft X reported the traffic in sight and I issued aircraft X to maintain visual separation. They did not reply. I repeated the instruction for aircraft X to maintain visual separation and aircraft X replied 'wilco; aircraft X.' at this point; the aircraft were 3.5NM apart. I then informed the apache sector that aircraft X was maintaining visual separation with aircraft Z. Apache sector replied that they turned their aircraft to a heading of 270 further turning the aircraft into the flight path of aircraft X; however apache also reported that aircraft Y was maintaining visual separation with aircraft X. Neither aircraft reported responding to a TCAS RA and the aircraft passed approximately 1.5 miles apart.I believe that fusion stitching gave me a bad radar return of aircraft X on a heading of 335 which made me turn aircraft X further right than a 350 heading. This caused aircraft X to be on a course which would put aircraft X and aircraft Y less than 3 miles apart. As a result of the turn further right than 350; the heading of 300 to pass behind aircraft Z but well in front of aircraft Y was delayed causing aircraft X to be in a position where aircraft X and aircraft Y were not going to be separated by 3 miles. I believe this issue will be resolved after year 2020 when aircraft are mandated to be equipped with ads-B giving accurate 1-second position updated instead of a fusion 'estimate' between radars returns.

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Original NASA ASRS Text

Title: P50 TRACON Controller reported a false radar target movement caused him to issue a vector to an aircraft which placed it into conflict with another aircraft.

Narrative: I was working the NAVAJO departure sector; which is the north departure sector at P50. NAVAJO has pre-arranged coordination airspace the with APACHE feeder sector. Aircraft X departed PHX on the ZEPER1 SID climbing to 8;000. I radar identified Aircraft X and climbed the aircraft to 9;000 observing there were aircraft in the EAGUL6 STAR arrival corridor descending to 10;000. When Aircraft X was approaching SPRKY; I observed a large gap between Aircraft Z (A320) and Aircraft Y (A321) in which with vectors I could continue Aircraft X's climb. After passing SPRKY I issued a heading of 030 to Aircraft X to allow them to be in a position to where I could keep the climb going with just a few more small vectors. I climbed Aircraft X to FL210 and subsequently turned them to a heading of 350 where it would fall 3 miles behind Aircraft Z but approximately 5 miles in front of Aircraft Y. After issuing the turn to heading 350; scanning for other traffic; and talking to another aircraft; I returned my scan to verify Aircraft X made the turn. I observed Aircraft X had made a turn to what I thought was approximately a 335 heading which was now putting Aircraft X too close to Aircraft Z. I needed Aircraft X on a heading of 350 so I told Aircraft X to turn 15 degrees right short vector for traffic (trying to get Aircraft X back on a 350 heading). It was my intention to keep Aircraft X on a 350 heading until they passed/diverged with Aircraft Z to which I could then turn Aircraft X to a heading of 300 to pass behind Aircraft Z (but well in front of Aircraft Y).In hindsight; I think what happened was that I think I observed a false return of Aircraft X on a 335 heading due to FUSION stitching and that Aircraft X was most likely on a 350 heading as assigned. When I assigned a 15 degree right turn to Aircraft X; they probably turned to a 005 heading which was less than 3 miles in front of Aircraft Y. Once I realized that Aircraft X was in a position and heading that was not intended; I turned Aircraft X to heading 300 attempting recovery and to get them to pass and diverge in front of Aircraft Y's flight path. Aircraft X delayed the turn after correctly reading back the heading and then confirmed the heading of 300. I told Aircraft X affirmative fly heading 300 immediately (in order to get the aircraft to turn in front of Aircraft Y). [I then] issued the A321 traffic to Aircraft X. Aircraft X reported the traffic in sight and I issued Aircraft X to maintain visual separation. They did not reply. I repeated the instruction for Aircraft X to maintain visual separation and Aircraft X replied 'Wilco; Aircraft X.' At this point; the aircraft were 3.5NM apart. I then informed the APACHE sector that Aircraft X was maintaining visual separation with Aircraft Z. APACHE sector replied that they turned their aircraft to a heading of 270 further turning the aircraft into the flight path of Aircraft X; however APACHE also reported that Aircraft Y was maintaining visual separation with Aircraft X. Neither aircraft reported responding to a TCAS RA and the aircraft passed approximately 1.5 miles apart.I believe that FUSION stitching gave me a bad radar return of Aircraft X on a heading of 335 which made me turn Aircraft X further right than a 350 heading. This caused Aircraft X to be on a course which would put Aircraft X and Aircraft Y less than 3 miles apart. As a result of the turn further right than 350; the heading of 300 to pass behind Aircraft Z but well in front of Aircraft Y was delayed causing Aircraft X to be in a position where Aircraft X and Aircraft Y were not going to be separated by 3 miles. I believe this issue will be resolved after year 2020 when aircraft are mandated to be equipped with ADS-B giving accurate 1-second position updated instead of a FUSION 'estimate' between radars returns.

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.