B737-800
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2
Situational Awareness; Distraction; Workload
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Airspace Structure; Human Factors
A B737 came over on the RNAV arrival. I was working my other aircraft when the B737 called to ask for clarification on what he was supposed to be doing. At that moment; it was clear the B737 was off the ground track for the RNAV arrival. It wasn't clear at the time if it was his clearance for the arrival that confused him or what. I began to give him a turn when I realized he had already descended below the MVA (Minimum Vectoring Altitude). In the same transmission; I asked if he can maintain his own terrain and obstruction clearance. He said he could; so I gave him a vector and altitude he currently was at to maintain. An hour or so the pilot called to apologize; and say it was their mistake they had come off course from the RNAV STAR.
A11 TRACON Controller reported they did not notice an aircraft had flown off course and into an area below the Minimum Vectoring Altitude.