ZDC ARTCC RADAR CTLR INADEQUATELY VECTORED TFC FOR SEPARATION.

Narrative

THE PROB AROSE DUE TO INCREASED TFC VOLUME GENERATED BY TSTM RERTES BY TMU. THE SECTOR WAS BUSY WITH NUMEROUS ACFT CLBING AND DSNDING. THE AIRBUS (EBOUND AT FL290) AND THE CHALLENGER (SBOUND; CLBING TO FL350) LOST SEPARATION OVER FKN VORTAC; DESPITE RECOGNITION OF CONFLICT AND TURNS INITIATED BY THE RADAR CTLR. I WAS WORKING THE DATA POS; HEARD THE RADAR CTLR ISSUE A 010 DEG HDG TO THE AIRBUS AND A 200 DEG HDG TO THE CHALLENGER. I INITIATED A 5 MI HALO ON THE AIRBUS AND MENTIONED THAT ADDITIONAL TURNS MAY BE NECESSARY TO MAINTAIN 5 MI. THE RADAR CTLR SAID 'TOO LATE NOW' AS THEY PASSED EACH OTHER WITH 4.3 MI. ADDITIONAL CAUSAL FACTORS INCLUDE OVERLAPPING DATA BLOCKS (DUE TO CONGESTION OF AIRSPACE) AND CALL SIGN TRANSPOSITION (CALL SIGN NUMBERS REVERSED INITIALLY; DELAYING THE AIRBUS TURN). BOTTOM LINE: TOO LITTLE; TOO LATE (TURNS); EVEN THOUGH CONFLICT WAS RECOGNIZED IN TIME TO AVOID SEPARATION LOSS. IN RETROSPECT; UTILIZATION OF ADDITIONAL TURNS OR USE OF ALT (STOPPING THE CHALLENGER'S CLB AT FL280) WOULD HAVE SOLVED THE DILEMMA.