Widebody; Low Wing; 4 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1.75
Confusion; Distraction; Situational Awareness; Troubleshooting
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance
Procedure
Aircraft X; was filed ...A590.HAMND...AMOTT…  I gave a restriction to cross AMOTT at 12;000 feet.  Aircraft X reached HAMND; and immediately made a sharp right turn off course; presumably toward the fix NONDA.  I had lower; slower moving traffic ahead and to the east of Aircraft X's route; and had I not caught the mistake; or had the other traffic been higher; there easily could have been a loss of separation.  I asked Aircraft X what routing they were showing.  They responded: 'AMOTT 8 arrival'; which is not what my strip said.  This was the second instance in 2 days of an aircraft not flying the routing we were showing in the NAS.  I spoke with the controller who worked the aircraft in the previous sector; and he said that he had not given any route change.  All other indications were that no route change had been issued by any previous ZAN controller; leading me to believe that the problem originated prior to Aircraft X entering ZAN airspace.  My guess is that either an incorrect flight plan from the previous Center was activated; the flight plan received from the other Center was incorrect; or the original clearance off of the departure airport differed from what the pilots were showing and it wasn't caught.As far as I understand; aircraft are usually cleared 'as filed' on long routes like this; and small errors in the routing thousands of miles from origin might go unnoticed.  More verification needs to be done between what the pilot's routing shows; and what is on the controller's strips.
ZAN Controller reports of an aircraft entering his airspace that takes a wrong turn. CPC queries pilot and determines route is different than what the controller had.