Narrative:

I was working the (R60/R31) position from about XA45 to XB30 am. I accepted handoffs to air carrier west and air carrier X from potomac approach (pct). Air carrier X was following air carrier west on a departure route over the gordonsville VORTAC (gve) from approach. The aircraft were about 7-8 NM apart. The conflict alert activated between these 2 aircraft. I asked air carrier west what his speed was and he said 'we were assigned 290 KTS or better and we are doing 290 KTS.' I asked air carrier X what his speed was and he said '320 KTS.' in response to the conflict alert; I leveled air carrier west off at his present altitude and then turned air carrier X right 270 while they were climbing. The aircraft were about 6 NM apart now. The turn resolved my situation but ended up getting air carrier X too close to aircraft Y. Aircraft Y was in pct approach's airspace and was apparently already in conflict with air carrier X before I turned the other aircraft to avoid an overtake error that should have not happened had both aircraft been assigned matching speeds by pct approach (as per LOA procedures). Aircraft Y was in pct approach's airspace and I missed aircraft Y's limited data block (ldb) in my scan for traffic. Had I seen it I would have done something different to resolve the conflicts. Pct approach never warned me about aircraft Y who was traffic for air carrier X. Contributing factors: moderate traffic all day; highly complex situations going on in another part of the sector which divides attention. How it was discovered: conflict alert activated. Corrective actions: I turned 1 aircraft and stopped the climb of another aircraft which solved the initial situation. In my traffic scan I should have seen aircraft Y. Had pct approach warned me about aircraft Y I could have issued different control instructions to resolve both conflicts. ZDC ARTCC is one of the busiest ctrs in the nation with probably the most complex airspace and aircraft 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 traffic during a single session. In the normal work day most fpl's will put in 4-6 hours working alone on an active control position. 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 traffic 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 controllers so we must work on position; or combined position for extended periods (usually between 30 min to 2+ hours 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 traffic either. It is easy to miss traffic or other things that might seem insignificant at the time but later find that they can be a problem when our minds are tired. Supplemental information from acn 767138: flight crew picked up visual contact with conflict aircraft not reported by ATC or displayed by TCAS. ATC reported contact when queried by flight crew and provided aircraft position. Light twin aircraft not reported or observed as conflict traffic for our flight due to TCAS failure and unknown ATC communication issues. Center was unaware of conflict until we reported visual contact with conflict aircraft.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.