Date: 202010
Local time of day: 0001-0600
Location: ZZZ.TRACON, US
Aircraft: Military
Operator: Military
Operating under: Part 91
Flight plan: VFR
Mission: Tactical
Flight phase: Final Approach
Airspace: Class C ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: Commercial Fixed Wing
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Workload; Situational Awareness; Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Critical; Airspace Violation All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Issued Advisory / Alert
Contributing factors: Procedure; Human Factors; Environment - Non Weather Related
Primary problem: Environment - Non Weather Related

Narrative: I'm not sure if; or how many errors I had; but I'm submitting this report for consideration. Everything described below happened within about 3 minutes and it wasn't until the dust settled about a half hour later I had time to reflect on things and wonder what just happened. I took [position name] Radar at or around XA:57z. I was working all TRACON airspace combined; no hand-off; no radar split and no CIC to help. I was all things TRACON. Sector was busy with; I don't know; 12; maybe 15 flights of aircraft talking to me. Everything fell to pieces 5 minutes after taking the position.Aircraft X [flight of 2 VFR] were returning from the Range Complex from the south; set up for about a 10 nm left base; coming fast; at 310 kts to beat Aircraft Y straight in for RWY XXR. I vectored Aircraft Y on a 270 Hdg down to 7000 (6500 mva) for sequencing to follow the Aircraft X [flight].  At or around XB:02Z; Aircraft Z in the southwest practice area; about 12 - 15 nm southwest of ZZZ called me but was blocked. He called again and stated he is 'Priority inbound; my engine just let go'. I told him to enter left traffic RWYXXR; I called Ground Control on the override; told them to roll the equipment for Aircraft Z emergency inbound had lost his engine. I tagged Aircraft Z as an emergency and then started issuing traffic to Aircraft Z to follow the Aircraft X flight; about 8nm straight in. I knew I needed to slow the problem down; and began by slowing my Aircraft A on north downwind to 180kts. I slowed Aircraft Y and all the other traffic in the queue to 180 kts and began vectoring people wide for sequencing. I looked about 15 nm east and realized Aircraft Y was at 6100 in my 6500 MVA; and descending! I told him to maintain 6500 (forgot to say low altitude alert). He acknowledged and descended to 5700. I told him to climb immediately to 9000 no delay through 8000. I needed to break him out to the south because it was going to be a three-way tie with him; Aircraft X and Aircraft Z. I had to get him above my MVA's to break him out to the south for re sequencing.Without benefit of reviewing the tapes to hear the audio; I'm very sure Aircraft Y was never cleared for a visual approach; but maybe I did and that was why he was so low.  Again; I don't have tapes to listen to and there's no management in the building to help me answer that question. Did I miss him read-back a wrong altitude? At some point in this fiasco; I realized the Aircraft Z way too fast (280kts) and catching the Aircraft X flight and told tower to move the Aircraft X flight to the south runway; 'Aircraft Z does not have them in sight'.By now; Aircraft Y was at 6000 slowly climbing but still in the face of Aircraft Z; 5 nm opposite direction at 6000; talking to tower with the Aircraft X flight are on short final. Next thing I know Aircraft Z is basing at 5000 and the Aircraft X flight are in the flare.  Aircraft Z had his hands full and mis judged his approach so he made S-Turns or a right 360 on final to get down and land.  I got Aircraft Y out of 7000 and turned him Heading 230 for sequencing following another flight of Aircraft X flight on a dogleg to follow the Aircraft A on the north downwind and another commercial aircraft straight in. All the fighters and air carriers parked north side and wanted RWY XXR; but I knew it would close behind the Aircraft Y so I changed them all to the south runway. I got everyone in line; speed controlled; cleared and visual separation applied.I switched Aircraft Y to the tower earlier than I would normally when I saw the Aircraft Z starting to base to about a 3 mile final and put him on the tower for landing clearance. I don't think I ever got a response from him that he had Aircraft X flight in sight. I was very rattled; in damage control mode and trying to fix the air carrier too low on final where I didn't expect him to be.Now that I had time to think about what just happened. Here's what I don't know:1.) Did Aircraft Z have Aircraft X in sight and pilot applied visual separation? He flew around a bit on  final and maybe even 360'd; was above the Aircraft X flight altitude at all times; was never behind them on final but did overfly the south final to maneuver north of it for XXR. 2.) Did I clear Aircraft Y for Visual approach?  I don't think so because I was intending to have him follow Aircraft X flight and I didn't even have time to try and tell him about Aircraft X flight yet. Did he read-back an incorrect altitude when I told him 7000? If he did; I didn't catch it.  Did he bust his altitude assignment? I believe he did because I wouldn't have issued such a low altitude in that 6500/7100/8000/9000 area on our final extending out from 20 nm. What was he doing so low in there? Well; for starters; I should have said 'LOW ALTITUDE ALERT' to Aircraft Y when he was at 6100' in my 6500 MVA. It was just unreal; I couldn't believe what I was seeing. What was he doing below 6500 there? I didn't clear him yet! I told him to climb; he acknowledged yet he descended further to 5700'!  I was incredulous and told him to immediately climb through 8000 to maintain 9000. He finally understood that and did what I instructed. Once Aircraft Z dropped his situation in my lap; I immediately and with out delay coordinated with the tower; did an 'EM' Slew/Enter so they could see he was the emergency and modified the SPAD for the north runway. I had data tag over-lapage (multifunction O/E doesn't work at TRACON so our auto-offset feature didn't do anything to keep data blocks from overlapping) and I didn't realize Aircraft Z was SO fast on a 2nm downwind. With the Aircraft X flight on a 5 nm straight in that math wasn't gonna work. He was catching them FAST and I pointed out traffic; he said 'looking'. I know he was busy and in a bind and I needed him to see those Aircraft X flight. I tried to fix it; saw that Aircraft Z was in position; already basing; needing a landing clearance; not going to physically catch the Aircraft X flight so I dumped him to the tower so I could try and fix the Aircraft Y who was not doing anything I wanted; needed or expected him to do. Plus; I had 12 other pilots going places and calling me all this time too. Everything transpired in 3 minutes; from the time I understood Aircraft Z was in trouble to the time where he was on final and I could deal with the other traffic.There's nothing that can be done 'to prevent a re-occurrence of this event'. You can't anticipate emergencies. That said; I should have issued a low altitude alert; and I should have had the Aircraft Z call the Aircraft X in sight or break the Aircraft X flight off final; sterilize everything and let the Aircraft Z do his thing. Also; this very same Aircraft Z has pulled this stunt on me in the past. He called with an engine failure; bombing into the left downwind at 280-300 kts. Prior to this incident; I didn't have other traffic to conflict with him. This was a rapidly devolving situation I did my best to manage and in retrospect realize a couple lapses in my control actions. I was just working the problem in the moment; trying to make planes miss and not overly concerned over 'words'.




Synopsis: TRACON Controller reported working a RADAR Positions in the TRACON combined and having too many aircraft resulting in a sequence that was not desired and a possible loss of separation.