Date: 201412
Local time of day: 1801-2400
Location: ZOA.ARTCC, CA
Light: Night
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZOA
ATC / advisory: Center ZOA
Second aircraft: Large Transport
Reporter organization: Government
Reporter function: Enroute; Oceanic
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Confusion; Human-Machine Interface; Troubleshooting; Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: Aircraft X had already been coordinated from Sector 35 to the Ocean Sector 4 at FL360.  The Sector 35 controller called back to make a speed amendment but instead of amending the speed to Mach .83 they used 083 knots.  This 'backed up' the aircraft significantly and placed his Aircraft Position Symbol (APS) over Nevada and put it in a System Preactive (coral box) state where the system wasn't probing that aircraft for conflicts.  The computer now shows his APS over Nevada while in reality the aircraft is about to progress over ZZZ intersection into the ocean without the system probing for conflicts.  Aircraft X was projected to be over ZZZ intersection around XX+00z.  It should also be noted that the system then booted the Aircraft X off ADS and CPDLC at this time.  This is almost exactly when myself and my developmental took the sector. At around XX+08z we received an ARP message from Aircraft X that was a position report sent via HF (via Commercial Radio) because they had been booted off ADS and couldn't log back in.  The HF report was out of conformance because the system thought the aircraft wasn't at the boundary yet.  Remember it was calculating positions based on speeds of 83 knots.  While this message was sitting in the queue we had already issued a climb to Aircraft Y from FL350 to FL380.  Aircraft Y was being probed for conflict and was between ZZZZZ intersection and ZZZZZ1 intersection roughly.  As we investigated the Aircraft X position report we decided to confirm it and then ask for their present position via 'CONFIRM POSITION'.  The Aircraft X came back with an identical position report.  We then accepted this at XX+13z and the APS appeared down the track between ZZZ intersection and ZZZ1 intersection; about 17nm in front of Aircraft Y who was still probing the climb from FL350 to FL380.  We immediately noticed that a climb through with 17nm had taken place and notified the supervisor.  Shortly after the Aircraft X was able to log back into ADS and CPDLC further confirming his position was accurate.  I would like to reference a colleague's report for more description as to the events that led up to this loss of separation.There should have been a 'logic' check by the system when the speed went from M.83 to 83 knots.  I don't know if there was and it was deleted by the previous controller; but if there isn't this could have been a safety net.  I think when there is such a significant change in an aircraft's APS when they are already connected to ADS and CPDLC; we should have gotten a notification.




Synopsis: ZOA Oceanic Controller reports of an aircraft speed being amended from Mach 0.83 to 83 knots causing incorrect position reports on the aircraft and a loss of separation.