Small Transport
Flight Crew Instrument; Flight Crew Commercial
Situational Awareness; Confusion; Distraction
Aircraft Equipment Problem Less Severe; Conflict Ground Conflict; Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach
Aircraft; Human Factors
MYF RNAV28R approach; circle to land 23. On final approach between fixes NESTY and PENNY aircraft descended to 2;000 feet prior to 2;500; the descent minimum at PENNY. MYF tower controller issued altitude alert and I corrected back to 2;500 feet. Continued approach and airport was visual; above minimums.Circled to 23; tower was trying to clear previous arrived aircraft off runway and I had to execute a missed approach. Tower stated to execute missed approach procedures. I looked at chart and it was to fly straight to 3;000. Raised gear and flaps and climbed to 3;000 feet. At 1;000 feet I engaged autopilot and contacted approach on a new frequency. Autopilot was having the aircraft descend and I disengaged autopilot and it was seemed to be still engaged and I struggled with controls to climb again. Departure control commanded that I climb to 3;000 and I stated that I seemed to be having trim issues as I was fighting to climb. I continued to the headings that were issued by Approach and returned for another approach without further incident. Suggest not using the autopilot until all desired settings are set; and review of missed approach procedures for circling approaches since they are not the same as depicted on the missed approach plate.
Pilot reported receiving a low-altitude alert from tower after descending below intermediate approach altitude.