B747 Undifferentiated or Other Model
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 9.0
Situational Awareness; Time Pressure
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Procedure; Human Factors; Airspace Structure
I was working arrival radar. Traffic volume was light and all radar positions were combined. I was working about 4 to 5 aircraft inbound. Aircraft X was the first of two aircraft inbound from the northeast and was eventually issued a heading of 255 and in a descent for the downwind for an ILS approach. The field and weather was VFR; but due to newly imposed restrictions; all aircraft to must conduct an instrument approach to the runway. Aircraft X was then instructed to turn right heading 260 and to descend to 3;000 feet. The pilot correctly read back the control instruction; and a few moments later his track was observed on a northbound heading. I then reissued a heading of 250 to turn the aircraft back on course for the downwind and to maintain 3;000 feet. He did not make a turn in a timely manner; so I issued a further turn to the southwest of 240 and instructed him to climb up to 4;000 feet. At the time I issued the heading and altitude instructions; the aircraft was at an appropriate altitude above the MVA(Minimum Vectoring Altitude) however; to the west northwest; there is an area with an MVA of 4;000 feet. It was my expectation that the aircraft would complete the turn and be clear of the higher MVA area at the current altitude; but issued the climb; just in case. To my recollection; the aircraft narrowly avoided the 4;000 feet MVA and was then vectored to continue on course to an approach. The Low altitude Alert warning did not alarm visually or audibly. The following day; I was asked about the incident by the Supervisor; and told that it was a significant event and that the aircraft flight path did cross through the corner of the 4;000 feet MVA and was still at an altitude below 4;000 feet. I did not issue the brasher warning to the pilot; as I prioritized my work to continue working the operation. I was informed that this event was discovered from a 'random' audit the next day. The replay confirms that the LA alert did not go off.  In my opinion; the event was caused because of a pilot deviation. I believe the incident was recognized in a timely manner; and while the direction of the turn may have taken the aircraft further away from the higher MVA; it was my belief that the aircraft had sufficient time and space to have complete his turn to the left and also remain clear from the higher MVA. This decision to turn the aircraft left was also done to reduce the potential flight of the aircraft and would return the aircraft on course in the most efficient manner. Consideration for issuing a LA alert would not make a difference in my opinion to ensure that the aircraft steered clear of the higher MVA.
An Approach Controller reported an aircraft did not comply with their vector in a timely manner and flew below the Minimum Vectoring Altitude.