Narrative:

I was holding aircraft over the pvd VOR. For bos I was attempting to get aircraft lower in the pattern. I was receiving handoffs that were going to hold as well and were at altitudes below the highest aircraft that was already in holding. I was contending with overlapping data tags. It was difficult to see the data tags; altitudes; and cid's. Approximately 4-5 mins before the incident; I assigned FL190 to air carrier X (MD88) and air carrier Y (E145). When air carrier Y started his outbound turn; I initiated a vector and descent to get some altitudes for inbounds. Approximately 1 min after I initiated the turn; air carrier X alerted me to an aircraft at his altitude in the hold. Air carrier X was on his inbound leg. I then turned air carrier Y 20 more degrees left but the error had already occurred. Prior to the incident; we dealt with a WX divert from another sector; divert fuel within the holding pattern; receiving an aircraft that was not supposed to enter our sector. Overlapping data tags; and inbounds already in conflict with the hold pattern. Prior to this session; I worked approximately 1 hour 56 mins in a busy sector. Mental fatigue was a factor. At the time of the incident; my supervisor was trying to get overtime in; staffing was getting low.

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Original NASA ASRS Text

Title: ZBW CTLR DURING HOLDING PROCS ASSIGNED 2 ACFT THE SAME ALT; FL190.

Narrative: I WAS HOLDING ACFT OVER THE PVD VOR. FOR BOS I WAS ATTEMPTING TO GET ACFT LOWER IN THE PATTERN. I WAS RECEIVING HDOFS THAT WERE GOING TO HOLD AS WELL AND WERE AT ALTS BELOW THE HIGHEST ACFT THAT WAS ALREADY IN HOLDING. I WAS CONTENDING WITH OVERLAPPING DATA TAGS. IT WAS DIFFICULT TO SEE THE DATA TAGS; ALTS; AND CID'S. APPROX 4-5 MINS BEFORE THE INCIDENT; I ASSIGNED FL190 TO ACR X (MD88) AND ACR Y (E145). WHEN ACR Y STARTED HIS OUTBOUND TURN; I INITIATED A VECTOR AND DSCNT TO GET SOME ALTS FOR INBOUNDS. APPROX 1 MIN AFTER I INITIATED THE TURN; ACR X ALERTED ME TO AN ACFT AT HIS ALT IN THE HOLD. ACR X WAS ON HIS INBOUND LEG. I THEN TURNED ACR Y 20 MORE DEGS L BUT THE ERROR HAD ALREADY OCCURRED. PRIOR TO THE INCIDENT; WE DEALT WITH A WX DIVERT FROM ANOTHER SECTOR; DIVERT FUEL WITHIN THE HOLDING PATTERN; RECEIVING AN ACFT THAT WAS NOT SUPPOSED TO ENTER OUR SECTOR. OVERLAPPING DATA TAGS; AND INBOUNDS ALREADY IN CONFLICT WITH THE HOLD PATTERN. PRIOR TO THIS SESSION; I WORKED APPROX 1 HR 56 MINS IN A BUSY SECTOR. MENTAL FATIGUE WAS A FACTOR. AT THE TIME OF THE INCIDENT; MY SUPVR WAS TRYING TO GET OVERTIME IN; STAFFING WAS GETTING LOW.

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.