ATC EQUIP PROB RADAR ACR X TCASII RA WITH VFR SMA Y. EVASIVE ACTION TAKEN.

Narrative

DULLES WAS IN A LIMITED RADAR CAPACITY USING CENRAP RADAR. ON 2 OCCASIONS DURING MY TIME ON THIS POS; MY A/N'S AND VIRGILES 'FLICKERED.' I; AND OTHER CTLRS IN MY FACILITY WERE HAVING PROBS TRACKING RADAR TARGETS. I WAS ROUTINELY LOSING VIRGILES; AND ON MANY OCCASIONS LOST BOTH VIRGILES AND A/N'S. A FEW ACFT (MAYBE 3 OR 4) THAT WERE SUPPOSED TO BE IN THE LIMITS OF MY RADAR COVERAGE; WENT INTO 'CST' STATUS FOR 2 OR MORE SWEEPS. ACR X CAME INTO MY AIRSPACE OVER ROBRT AT 10000 FT. I INSTRUCTED ACR X TO 'EXPECT VISUAL APCH RWY 1R; CROSS 20 MI NW OF ARMEL AT 5000 FT.' APPROX 5 MI S OF THE FDK VOR; ACR X INFORMED ME 'ACR X IS FILING A NEAR MIDAIR NOW.' I THEN TOLD ACR X THAT I OBSERVED A VFR TARGET SMA Y 6 O'CLOCK LESS THAN 1 MI; NEBOUND; ESTIMATED; INDICATING 5700 FT UNVERIFIED. I DID NOT ISSUE THE TFC PRIOR TO ACR X RPT; NOR WAS TFC OBSERVED PRIOR TO ACR X RPT. I INFORMED THE SUPVR; AS DID I INFORM HIM OF THE RADAR PROBS I WAS EXPERIENCING PRIOR TO THE INCIDENT. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: RPTR STATED THAT ACR X TOOK EVASIVE ACTION BECAUSE OF TCASII RA. RPTR FAILED TO ISSUE TFC BECAUSE WITH THE RADAR PROBS SHE WAS TAKING A MANUAL RADAR HDOF FROM ANOTHER POS AND WAS DISTRACTED.