Air Traffic Control Fully Certified
Distraction
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Aircraft; Human Factors
Aircraft X was turned from the downwind to SAN and cleared to follow traffic for a visual approach. Aircraft Y was cleared for an approach from straight in behind Aircraft X. Aircraft X did not turn towards the airport in an acceptable amount of time causing me to cancel Aircraft Y's approach clearance. I stopped Aircraft Y at 3800 ft. which is the MVA in that area and vectored him to a heading of 340 to gain separation with the intent to re-clear him after separation was ensured. Aircraft Y stated that he had continued descent. I issued Aircraft Y a low altitude alert and eventually climbed him to 5000 for re-sequencing. Aircraft X should have turned to final sooner. I could have ensured the turn but experience told me that [company] typically turns to final within an acceptable window for this situation to work.
SCT Controller reported B737 descended below assigned altitude; entering a lower MVA.