Any Unknown or Unlisted Aircraft Manufacturer
Air Traffic Control Fully Certified
Troubleshooting
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Separated Traffic
ATC Equipment / Nav Facility / Buildings; Environment - Non Weather Related
A Mode C intruder popped up on airspace at FL300. This started a conflict alert with Aircraft X and another aircraft already talking to [another sector]. I turn Aircraft X 15R to avoid the mode C intruder. After I was clear of the conflict I turn Aircraft X back to [their destination]. I watch the mode C intruder Descend from FL300 all the way down to 100 MSL and the track moved very little (seem to hover). At this point I dropped the track.
ZID Controller reported an airborne conflict with a mode-C intruder.