ZDC CTLR EXPERIENCED OPERROR AT FL230; TURNING AN INTRAIL ACFT FOR SPEED DIFFERENTIAL BUT FAILING TO OBSERVE CONFLICTING TFC IN PCT'S AIRSPACE.

Narrative

I WAS WORKING THE (R60/R31) POS FROM ABOUT XA45 TO XB30 AM. I ACCEPTED HDOFS TO ACR W AND ACR X FROM POTOMAC APCH (PCT). ACR X WAS FOLLOWING ACR W ON A DEP RTE OVER THE GORDONSVILLE VORTAC (GVE) FROM APCH. THE ACFT WERE ABOUT 7-8 NM APART. THE CONFLICT ALERT ACTIVATED BTWN THESE 2 ACFT. I ASKED ACR W WHAT HIS SPD WAS AND HE SAID 'WE WERE ASSIGNED 290 KTS OR BETTER AND WE ARE DOING 290 KTS.' I ASKED ACR X WHAT HIS SPD WAS AND HE SAID '320 KTS.' IN RESPONSE TO THE CONFLICT ALERT; I LEVELED ACR W OFF AT HIS PRESENT ALT AND THEN TURNED ACR X R 270 WHILE THEY WERE CLBING. THE ACFT WERE ABOUT 6 NM APART NOW. THE TURN RESOLVED MY SITUATION BUT ENDED UP GETTING ACR X TOO CLOSE TO ACFT Y. ACFT Y WAS IN PCT APCH'S AIRSPACE AND WAS APPARENTLY ALREADY IN CONFLICT WITH ACR X BEFORE I TURNED THE OTHER ACFT TO AVOID AN OVERTAKE ERROR THAT SHOULD HAVE NOT HAPPENED HAD BOTH ACFT BEEN ASSIGNED MATCHING SPDS BY PCT APCH (AS PER LOA PROCS). ACFT Y WAS IN PCT APCH'S AIRSPACE AND I MISSED ACFT Y'S LIMITED DATA BLOCK (LDB) IN MY SCAN FOR TFC. HAD I SEEN IT I WOULD HAVE DONE SOMETHING DIFFERENT TO RESOLVE THE CONFLICTS. PCT APCH NEVER WARNED ME ABOUT ACFT Y WHO WAS TFC FOR ACR X. CONTRIBUTING FACTORS: MODERATE TFC ALL DAY; HIGHLY COMPLEX SITUATIONS GOING ON IN ANOTHER PART OF THE SECTOR WHICH DIVIDES ATTN. HOW IT WAS DISCOVERED: CONFLICT ALERT ACTIVATED. CORRECTIVE ACTIONS: I TURNED 1 ACFT AND STOPPED THE CLB OF ANOTHER ACFT WHICH SOLVED THE INITIAL SITUATION. IN MY TFC SCAN I SHOULD HAVE SEEN ACFT Y. HAD PCT APCH WARNED ME ABOUT ACFT Y I COULD HAVE ISSUED DIFFERENT CTL INSTRUCTIONS TO RESOLVE BOTH CONFLICTS. ZDC ARTCC IS ONE OF THE BUSIEST CTRS IN THE NATION WITH PROBABLY THE MOST COMPLEX AIRSPACE AND ACFT DENSITY. THE TRAINING REGIMEN DEVELOPMENTALS GO THROUGH WILL SCREEN OUT INDIVIDUALS THAT ARE UNABLE TO COMPLETE THE TRAINING. IF THEY COMPLETE THE TRAINING THEN THEY HAVE SHOWN THE ABILITY TO HANDLE A GOOD DEAL OF TFC DURING A SINGLE SESSION. IN THE NORMAL WORK DAY MOST FPL'S WILL PUT IN 4-6 HRS WORKING ALONE ON AN ACTIVE CTL POS. AND WE TAKE A LOT OF PRIDE IN THE FACT THAT WE CAN DO THAT AND MAKE IT WORK EFFECTIVELY MOST OF THE TIME. WITH THE AMOUNT OF TFC THAT GOES THROUGH ZDC ON A DAILY BASIS; THAT'S A GOOD DEAL OF MIND WORK THAT GOES ON IN A DAY'S WORK. IT IS VERY EASY TO GET MENTALLY TIRED DURING A WORK DAY; ESPECIALLY IF IT'S A REALLY BUSY DAY. I HAD ALREADY HAD A BUSY MORNING ON THIS DAY AND IT WAS JUST BEFORE MY LUNCH BREAK WHEN THIS SITUATION AROSE. SO I WAS MOST LIKELY SLIGHTLY MENTALLY FATIGUED. THE FACILITY IS SHORT OF CTLRS SO WE MUST WORK ON POS; OR COMBINED POS FOR EXTENDED PERIODS (USUALLY BTWN 30 MIN TO 2+ HRS AT A TIME). AFTER MANY YRS DOING THIS ROTATING SHIFTS IT DOESN'T TAKE MUCH TO BECOME MENTALLY FATIGUED. A CO-WORKER WAS TRAINING A DEVELOPMENTAL ON THE MANUAL; OR 'D' SIDE AT THE SAME TIME AND THEY DIDN'T SEE THE OTHER TFC EITHER. IT IS EASY TO MISS TFC OR OTHER THINGS THAT MIGHT SEEM INSIGNIFICANT AT THE TIME BUT LATER FIND THAT THEY CAN BE A PROB WHEN OUR MINDS ARE TIRED. SUPPLEMENTAL INFO FROM ACN 767138: FLT CREW PICKED UP VISUAL CONTACT WITH CONFLICT ACFT NOT RPTED BY ATC OR DISPLAYED BY TCAS. ATC RPTED CONTACT WHEN QUERIED BY FLT CREW AND PROVIDED ACFT POS. LIGHT TWIN ACFT NOT RPTED OR OBSERVED AS CONFLICT TFC FOR OUR FLT DUE TO TCAS FAILURE AND UNKNOWN ATC COM ISSUES. CTR WAS UNAWARE OF CONFLICT UNTIL WE RPTED VISUAL CONTACT WITH CONFLICT ACFT.