Military Trainer
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 19
Communication Breakdown; Situational Awareness
ATC Issue All Types; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Procedure
Aircraft X had been in the radar pattern at ZZZ. He questioned his climb out while on approach (as it was amended on his last approach and wasn't reiterated on this approach). After listening to the tape he was given heading 260 and 4;000 feet by the Local Controller and read it back correctly. Upon checking in with the Departure Controller; he said he was at 3;000 feet with request. The Departure Controller took his next request and turned him on downwind. After listening to the tape; Aircraft X questioned whether he should be at 3;000 or 4;000 feet; but was stepped on. I heard the low altitude alert go off; saw Aircraft X at 3;100 feet inside the antennae area- where the Minimum Vectoring Area is 3;500 feet. I instructed the Controller to climb Aircraft X immediately; he did and Aircraft X climbed.We discussed earlier opening up final sector. If we had; all of our controllers would have been on position. We also discussed giving the final to Radar East; but it would only have put all/most of the traffic on the other scope. In the future; I would insist that more of the military aircraft do approaches at an air force base in our airspace; not most of them at ZZZ. One was sent there; but I would send more. This would divide the workload better.
TRACON Controller reported a military training flight was assigned 4;000 feet; but stopped their climb at 3;000 feet and flew below the Minimum Vectoring Altitude.