Small Aircraft
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3.5
Training / Qualification; Situational Awareness; Communication Breakdown; Distraction
ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Human Factors; Airspace Structure
I was the OJT Instructor on the sector. Aircraft X requested pop up IFR and to hold. The trainee issued holding instructions (per pilot request) over the VOR on a radial. I heard it was the 310 degree radio but the pilot was actually requesting the 130 degree radial. After two turns in holding the developmental noticed the aircraft entering a 5700 foot Minimum Vectoring Altitude(MVA) so he climbed the aircraft to 6000 feet. No further incident. The developmental is far along in hours and I was wanting to let him work the position unbothered so I was sitting and monitoring the adjacent scope. I wasn't worried about MVA because I heard 310 radial and that would keep the aircraft toward lower MVAs. Expectation bias and hear back error on my part. I should have more vigilant involvement during training.
[Report narrative contained no additional information]
A TRACON Controller instructing a trainee observed the trainee allow an aircraft to fly below the Minimum Vectoring Altitude.