Small Aircraft
Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Human Factors
Aircraft X was on the missed approach. They had been instructed 3 separate times to climb to 4000 feet on the missed approach because Aircraft Y was holding at a fix at 5000 to 6000 feet. They read it back correctly each time. Two Sectors were combined and rather than have me split off one sector the Supervisor directed me to get the Controller out and another Controller would then come and split off the sector. It was fairly busy and I was not happy with the plan but did as I was told. During the course of my scan I noted that Aircraft X had climbed through their assigned altitude. I issued a descent to 4000 feet; issued traffic to Aircraft X and Aircraft Y and cancelled Aircraft Y's block altitude and had them climb to 6000 feet and initiated a turn.This was purely a pilot deviation and nothing I did here is my fault but what annoys the heck out of me is that we are constantly be put into situations where we are forced to work unassisted under conditions that historically we would have always had a D-Side (Radar Assist) for. We use strips here and those take up controller time. Had I been given a D-Side to handle my strips or if the sector had been split like it should have been in my opinion then I could have caught this much sooner; perhaps before even losing separation. Feels like we never have any extra help available when you need it. If you do ask for help the schedule can't support opening even one position without driving everyone to 2 hours time on position. The culture has shifted to never splitting sectors and never opening D-Sides because of it.
HCF TRACON Controller reported an aircraft climbed above their assigned altitude into conflict with traffic in a holding pattern.