Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.0
Human-Machine Interface; Situational Awareness
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem
Environment - Non Weather Related; Aircraft; Human Factors
Aircraft X checked in descending via the STAR landing north and reported their altitude as 18;500 feet; which matched the Mode C readout. This appeared to be a very high altitude and they had a crossing restriction coming up which was 12000-11000 feet. While the aircraft was over [fix]; the mode C showed 14500 feet. I asked Aircraft X to say altitude; and the pilot reported '12;000 feet. At that point the Mode C disappeared off the screen and they became transponder only. The pilot then said 'Uh we're having some issues with our Mode C; we'll try another one'. The aircraft continued to track the arrival with no altitude readouts. There was another crossing restriction of 9;000 feet coming up as well. After they passed that fix; their Mode C became active again and showed 9;000 feet.I suggested that local management needed to follow up via a brasher warning; to which they declined. We had a verified Mode C readout that was 2;500 feet high on the arrival when the Mode C disappeared; which would be seem to be a pilot deviation.
CLT TRACON Controller reported an aircraft's Mode C quit working after it appeared it would not make a crossing restriction.