ATC RADAR CTLR BECAME DISTR AND ALLOWED LTSS IN A CLB AND DSCNT SITUATION. VECTOR TURNS PREVENTED A SERIOUS SITUATION TO DEVELOP FURTHER.

Narrative

I WAS WORKING AT THE LOW ALT SECTOR IN THE ROANOKE; VA AREA. TOOK A HDOF FROM ROA APCH ON AN ACR MLG FILED FOR FL240 FROM ROA V260 RNL -- ORD. ON INITIAL CONTACT WITH MLG; I CLBED MLG TO FL230. ABOUT THIS TIME; I TOOK A HDOF FROM ZID ON AN SMT; FLT PLAN RAC -- ROA. AT FL230 DSNDING TO 11000; THE ACFT ARE ON OPPOSITE COURSES. CONSIDERING THE PERFORMANCE OF BOTH ACFT; I DECIDED TO LEAVE BOTH ACFT ON THEIR OPPOSITE DIRECTION COURSES AND MONITOR THEIR PROGRESS SO I COULD TAKE AN ALTERNATE COURSE OF ACTION IF IT BECAME NECESSARY. AT THIS TIME; I WAS MODERATELY BUSY WITH OTHER TFC IN THE SECTOR. DURING THE NEXT FEW MINS; MY WORKLOAD INCREASED CONSIDERABLY AND MY ATTN WAS DIVERTED FROM THIS CLBING DSNDING SITUATION. ABOUT 4 OR 6 MINS LATER; I NOTICED THAT THE 2 ACFT ARE ABOUT 10 OR 12 MI APART; HEAD-ON; AND THE SMT IS STILL TOO FAR ABOVE THE MLG FOR THEM TO PASS WITH SUFFICIENT VERT OR HORIZ SEPARATION. IN FACT; IT LOOKED LIKE THEY MIGHT COLLIDE IF I DIDNþT TAKE IMMEDIATE ACTION. ACCORDING TO MODE C INFO; THE SMT WAS STILL ABOVE FL180 AND THE MLG OUT OF 16000 STILL CLBING. I TELL THE SMT TO MAINTAIN FL180 AND TURN L IMMEDIATELY TO A HDG OF 090 DEG. THE SMT ACKNOWLEDGES THE TURN AND SAYS WEþLL CLB BACK UP TO FL180. BY THIS TIME; THE CONFLICT ALERT IS FLASHING AND THE MLG SHOWS THROUGH 17000. I FIGURE BY THIS TIME TO STOP THE MLG CLB WOULDNþT HELP THE SITUATION AND WOULD ONLY TAKE MORE TIME IN A CLRNC; SO I TELL THE MLG TO TURN L HDG 270 DEGS IMMEDIATELY. THE 2 ACFT PASS 4.3 MI HORIZLY AND 200 FT SEPARATION. AS SOON AS BOTH ACFT ARE CLR OF EACH OTHER; I CLR THEM BACK ON COURSE. AS REVEALED BY INVESTIGATING THE RADAR COMPUTER DATA; IF I HAD TAKEN NO ACTION; THE ACFT WOULD HAVE PASSED WITH MORE THAN THE REQUIRED SEPARATION MIN. I HADNþT FULLY TAKEN INTO ACCOUNT THE LAG IN THE MODE C READOUT WHEN HIGH PERFORMANCE ACFT ARE CLBING OR DSNDING. MY FIRST REACTION TO THE SITUATION AS I SAW IT WAS THAT I HAD TO DO SOMETHING QUICK TO AVERT A POSSIBLE DISASTER. AS IT TURNED OUT; MY JUDGEMENT WAS GRIEVOUSLY IN ERROR. I SHOULD HAVE MONITORED THIS SITUATION CLOSER SO AS TO ENSURE SEPARATION FROM THE VERY FIRST CLRNC.