Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3.5
Communication Breakdown; Situational Awareness; Training / Qualification
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance
Human Factors
Aircraft X was on the SILCN 4 arrival landing RWY 12R. He was instructed; 'After EDMND maintain 030.' After Aircraft X reached that fix he started to descend rapidly. The developmental; without observing the rapid descent told the aircraft to descend to 020. The aircraft was at the 040 ft MVA when he issued this instruction. I told the developmental to tell Aircraft X to maintain 030. The aircraft was at 032 when he was instructed to maintain 030 but he continued descending to 023 before he climbed back up again. This was an unusually fast descent. The aircraft hit the 030 ft MVA at 023. I'm going to override his transmissions whenever he does or says something that I don't like instead of telling him to fix it. I'm also going to ask for a training team meeting whenever I see my supervisor and discuss possibly SET (Special Enhanced Training) training for MVAs.
TRACON Instructor reported a developmental issued an altitude below the MVA; and the aircraft descended rapidly below the MVA.