Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3.75
Confusion; Communication Breakdown; Distraction; Situational Awareness
Aircraft Equipment Problem Less Severe; Airspace Violation All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft; Equipment / Tooling; Procedure; Human Factors
Aircraft X checked on frequency and a few minutes later asked if SLC center told us about a warning light. I advised him they didn't and asked what it was about. The pilot responded with there was a warning light about their RVSM status but all of his altimeters were working and showing him level at FL390. This answer led me to believe that he was still able to be in RVSM airspace and I advised him if any issues with any altimeters arose he would not be allowed to continue flight in RVSM airspace. While he was in the sector his flight path crossed another aircraft who was less than 5 miles and 1000 feet. It was determined later that Aircraft X was not capable of RVSM and should have been descended into non-RVSM airspace.More of an understanding of what was going on with the aircraft at the time. If I would have understood that he needed to be descended at the time of him advising us then I would have done so; instead I treated it as just an advisory.
ZDV Controller reports of an aircraft that should not have been in RVSM airspace due to an equipment problem related to the altimeters on the aircraft.