Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3
Situational Awareness; Training / Qualification
ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Human Factors; Procedure; Airspace Structure
I was training a developmental on his first sector in our area. Aircraft X was on a left downwind at 5100 feet. There was an aircraft on an RNAV Arrival that was going to be second. The developmental turned Aircraft X on a base and descended him to 3000 feet because he was anticipating that Aircraft X wasn't going to descend into the 4700 foot Minimum Vectoring Altitude (MVA). Aircraft X descended quite rapidly and clipped the 4700 foot MVA at around 4400 feet. I didn't expect Aircraft X to descend so quickly. I will make sure the developmental uses the appropriate altitudes and not use anticipation.
TRACON Controller reported an aircraft descended quicker than anticipated and flew below the Minimum Vectoring Altitude.