ZAB CTLR DESCRIBED CONFLICT EVENT WHEN TARGETS 'JUMPED;' RESULTING IN A TCAS RA AND CONFLICT ALERT. PLAYBACK CONFIRMED NO SEPARATION LOSS.

Narrative

ACFT X ON AN IFR FLT PLAN AT FL330 N OF FTI VOR DIRECT GCK AND ACFT Y IFR HPN..SAF. ACFT Y WAS DSNDING FROM FL400 TO FL340 DUE TO ACFT X BEING IN CONFLICT ABOUT 5.0 LATERAL SEPARATION. I GAVE ACFT Y A 10 DEG L TURN TO AVOID ACFT X AND TO CONTINUE THE ACFT'S DSCNT INTO SAF. THE COMPUTER SHOWED 5.1 - 5.3 MI LATERAL SEPARATION. WHEN THE 2 ACFT WERE PASSING SIDE-BY-SIDE THE BEACON TARGET OF ACFT X JUMPED TOWARDS ACFT Y ABOUT 1/3 - 2/3 OF A MI FOR 2-3 RADAR UPDATES AND THEN JUMPED BACK TO THE ORIGINAL COURSE TRACK. THIS 'TARGET JUMP' CAUSED THE CONFLICT ALERT TO ACTIVATE AND IT PRINTED WITH A LOSS OF SEPARATION. THE COMPUTER REPLAY; FALCON; SHOWED THE TARGET JUMP WAS THE CAUSE OF THE SEPARATION LOSS AND THAT HAD THE TARGET JUMP NOT TAKEN PLACE THERE WOULD HAVE BEEN NO LOSS OF SEPARATION. ACFT X RECEIVED A TCAS RA; WHICH SEEMS TO HAPPEN AT ZAB WITH LESS THAN 5.5 MI SEPARATION IN A CLB OR DSCNT MODE. THE RADAR AREA IN WHICH THIS EVENT TOOK PLACE IS KNOWN FOR SPD JUMPS BUT NOT LARGE TARGET JUMPS.