Date: 201206
Local time of day: 1801-2400
Location: ZDC.ARTCC, VA
Aircraft: Commercial Fixed Wing
Flight plan: IFR
Flight phase: Descent
Reporter organization: Government
Reporter function: Other / Unknown
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Human-Machine Interface; Situational Awareness
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors; ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: I had just arrived for my shift and proceeded to get the briefing for BLR/EKN Sector. The outgoing Controller explained that it had been fairly busy; but was starting to slow down. There was one aircraft landing MRB that was deviating for weather; and a D-Side developmental receiving training on the sector; and about seven aircraft in the sector with more in hand off status. As the relieved Controller stepped back and I sat down I heard him talking to the D-Side trainer about high/low boundaries in Cleveland's airspace and to which sector an aircraft had been handed off. I roger'ed an aircraft check-in and then looked down at the keyboard to sign-in; while next to me; I heard to D-Side developmental make several calls about the aircraft that was deviating. As I finished signing-in; Air Carrier X checked on. I looked back up at the scope; located the Air Carrier X; saw he was in the shelf for BWI arrivals and descended the aircraft to FL210. I then proceeded to make other clearance and discussed the deviating aircraft with the D-Side developmental. Less than a minute later; Cleveland called on the shout line and the D-Side developmental answered the line; after which her trainer leaned forward and asked me if I had descended the Air Carrier X. I said yes and asked why; to which he replied that there was an aircraft in the self at FL250. When I moved Air Carrier X Data Block; I could see a limited at FL250 just behind the Air Carrier X. Air Carrier X had already begun his descent; resulting in a loss of separation (4.07 miles and 200 feet). At that point I asked the D-Side trainer who the limited was and if we had gotten a point out on him. The D-Side trainer then explained that the previous Controller had worked that aircraft along our boundary with Cleveland and had handed it off and switched it a while back but that it was a slow moving aircraft. He then questioned the developmental; if he/she had taken down the Data Block; to which he/she replied no. At that point I realized what had happened; that the Data Block had timed out and fallen off the scope; which happens often with Cleveland along that boundary; and since I had actually never worked the aircraft; I didn't realize it was out there. The D-Side trainer and the previous R-Side are both new to the sector and didn't realize that we often have this problem with Data Blocks along the boundary with Cleveland; and thus didn't know to look for it. When the tape was reviewed; it was found that the Data Block had been there when I received the briefing; but that in the time I looked down to sign-in and then back up at Air Carrier X check-in; the Data Block had dropped off the scope.This is a repeating problem with Data Blocks that are handed-off early to Cleveland; I can remember being warned when I first started training on BLR/ELK to now flash those particular Data Blocks early. Data Blocks that have not left a sector should not fall off or time out on their own. If the Data Block had been there; I would not have descended Air Carrier X.




Synopsis: ZDC Controller described a probable loss of separation event occurring immediately after a position relief. The reporter listed an on going data block drop problem near a common boundary with ZOB as the causal factor.