Medium Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Radar 14
Communication Breakdown; Training / Qualification
ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Human Factors; Procedure
I was instructing. Trainee issued a descend to 040 from 090 to Aircraft X. Aircraft X descended through a 055 and 047 MVA. Trainee anticipated descent rate wouldn't be a factor. I was researching a TEC route for an IFR overflight; and failed to prevent Aircraft X from descending through the MVAs.Do not allow trainees to anticipate descent rates. Issue altitudes that satisfy MVAs.
SBA TRACON ATC instructor reported a trainee issuing an aircraft a descent below the MVA.