Fairbanks TRACON controller reported of anticipating a pilot's descent to be above the minimum vecto...

Attributes
ACN	1402369
Time
Date	201611
Local Time Of Day	0001-0600
Place
Locale Reference	FAI.Airport
State Reference	AK
Aircraft 1
Make Model Name	Medium Transport
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 3
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

Narrative:

I turned aircraft X to a 015 heading and issued a pilot discretion descent to 4;300 while the aircraft was still in a 5;000 minimum vectoring altitude (MVA). Based on the aircraft's descent; I was anticipating the aircraft would be out of the 5;000 MVA and crossed into the lower; 2;400 MVA; before descending below 5;000. I glanced away from the radar; and when I turned back; the aircraft had already crossed the MVA line; but had also descended to maintain 4;300. Falcon replay showed that the aircraft descended below the MVA for approximately one mile. Don't base a pilot's discretion descent on expectation bias.

Original NASA ASRS Text

Title: Fairbanks TRACON Controller reported of anticipating a pilot's descent to be above the Minimum Vectoring Altitude when he issued the descent. The pilot descended quicker than the Controller thought and ended up having a Minimum Vectoring Altitude violation.

Narrative: I turned Aircraft X to a 015 heading and issued a pilot discretion descent to 4;300 while the aircraft was still in a 5;000 Minimum Vectoring Altitude (MVA). Based on the aircraft's descent; I was anticipating the aircraft would be out of the 5;000 MVA and crossed into the lower; 2;400 MVA; before descending below 5;000. I glanced away from the radar; and when I turned back; the aircraft had already crossed the MVA line; but had also descended to maintain 4;300. Falcon replay showed that the aircraft descended below the MVA for approximately one mile. Don't base a pilot's discretion descent on expectation bias.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Fairbanks TRACON controller reported of anticipating a pilot's descent to be above the minimum vectoring altitude when he issued the descent. The pilot descended quicker than the controller thought and ended up having a minimum vectoring altitude violation.