Date: 201708
Local time of day: 1201-1800
Location: ZNY.ARTCC, NY
Flight conditions: Marginal
Aircraft: B777 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 129
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZNY
ATC / advisory: Center ZNY
Second aircraft: A321
Reporter organization: Government
Reporter function: Enroute; Oceanic
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Time Pressure; Human-Machine Interface; Confusion; Situational Awareness
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Procedure; ATC Equipment / Nav Facility / Buildings; Aircraft; Airspace Structure; Company Policy; Manuals
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: Sector 81 called to coordinate Aircraft X with myself at sector 89. Coordination was probed and accepted without conflict for Aircraft X at FL360. [Five minutes later] a red conflict began flashing between Aircraft Y at 36;000 feet northbound on the airway and Aircraft X. I called sector 81 to re-coordinate Aircraft X at a different altitude. When I initially probed the aircraft at 36;000 feet; the probe in the coordination window for Aircraft X still showed no conflicts despite the data blocks flashing red conflict and a conflict window. Despite the coordination window showing no conflict; I re-coordinated Aircraft X at 37;000 feet.Sector 81 called with an altitude revision for Aircraft X. The aircraft was requesting 38;000 feet so I opened the coordination window; probed the aircraft at 38;000 feet which probed with no conflict so the aircraft was accepted at 38;000 feet. Sector 81 called for Aircraft X requesting direct to either GRATX or LFANO due to weather. Because the aircraft was approaching the boundary; I assumed the aircraft to probe the change in profiled route. Upon assuming the aircraft; a conflict appeared between Aircraft X and Aircraft Z. Aircraft Z was flying northbound on the airway at 38;000 feet.The conflict window showed 9 minutes and 23 seconds on the cross with 15 minutes needed for required minimum separation. At that point; I told sector 81 the aircraft needs to descend or climb 1;000 feet. Sector 81 immediately descended the aircraft to 37;000 feet and I advised them that direct to LFANO was approved. I completed updating the aircraft's profile and completed tasks and took a break. At some point before my break; I measured the two aircraft using the tool in Advanced Technologies and Oceanic Procedures (ATOP) and it showed 35 miles; however they were separated by 1;000 feet at that point and I don't know the closest point in mileage the aircraft got. A [report] is also being filed and the supervisor was notified.It appears as though there is an issue with ATOP in recognizing conflicts. This is a serious issue that needs to be remedied immediately. If this isn't a system issue and ATOP is working as designed; a briefing for all controllers needs to occur to explain what happened and how to avoid this.




Synopsis: ZNY Center Oceanic Controller reported they had less than required separation between two aircraft on crossing courses even though the ATOP tool did not identify a separation problem.