D21 CTLR EXPERIENCED TCASII RA WITH ACFT WITH NO DATA BLOCK INFO.

Narrative

ACR X; INBOUND TO DTW; FROM ARR FEEDER E; IS HANDED OFF TO CTLR 'A;' WHO IS WORKING FINAL ARR E. CTLR 'A' ACKNOWLEDGES AND ISSUES ACR X DSCNT TO 5000 FT. ALMOST SIMULTANEOUSLY ACR X (IDENTICAL CALL SIGN) DEPARTS DTW AND CONTACTS DEP CTL. (CTLR 'B') ARTS COMPUTER IS NOT ABLE TO TRACK IDENTICAL CALL SIGNS WHICH LEADS TO A LIMITED DATA DISPLAY ON ACR X (DEP) CTLR 'B' RECOGNIZES THE FACT THAT DUPLICATE CALL SIGNS EXIST AND; WITHOUT REALIZING ANOTHER ACTIVE TRACK IS IN PROGRESS; INADVERTENTLY REMOVES THE COMPUTER TRACK ON ACR X (INBOUND). THIS CAUSES ACR X (INBOUND) TO DISAPPEAR FROM CTLR A'S DISPLAY LEAVING ONLY A LIMITED TRACK INDICATING ALT ONLY. APPROX 10 SECONDS AFTER ACR X (INBOUND) INITIALLY CHKED ONTO CTLR A'S FREQ; CTLR 'A' BEGAN A POS RELIEF BRIEFING FOR CTLR 'C' WHO WAS ASSUMING CTL OF THE SECTOR. CTLR 'A' USED THE POS RELIEF CHKLIST AND THE RELIEF BRIEFING WAS RECORDED. CTLR ' A' FAILED TO RECOGNIZE ACR X HAD DISAPPEARED FROM THE RADAR DISPLAY AND THEREFORE DID NOT INCLUDE THE ACFT IN THE BRIEFING. CTLR 'C' DID NOT RECOGNIZE THE LIMITED TRACK ON ACR X (INBOUND) WHEN HE RECEIVED A XMISSION FROM ACR X (INBOUND) INDICATING HE WAS RESPONDING TO A TCASII RA BEING IN CONFLICT WITH AN ACR DC9 ON APCH TO A PARALLEL RWY. THE DC9 WAS IN COM WITH CTLR 'D;' (FINAL ARR W) WHO WAS ALSO RESPONDING TO A TCASII RA. TFC WAS LIGHT TO OCCASIONAL MODERATE ON ARR FEEDER SECTORS; AND LIGHT ON FINAL ARR SECTORS. ALL ARR SECTOR POS WERE STAFFED.