Commercial Fixed Wing
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 8
Human-Machine Interface; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Procedure; ATC Equipment / Nav Facility / Buildings
Aircraft X was on route level FL350. Aircraft Y was on a vector to achieve spacing landing SLC at FL350. Aircraft X was a bit faster (I think 15 kts or so). I turned Aircraft Y back to EFFTA. My D side brought color on EDST. This is when I realized the two aircraft were traffic. I descended Aircraft Y to FL340 and turned Aircraft X 30 degrees left. I told Aircraft Y to report level FL340 and didn't get a read back. I was watching the CA (Captain) on the scope and saw as close as 4.99 NM. First I should have scanned and noticed the traffic before turning Aircraft Y back. Next I should have pushed Aircraft Y down to FL330 (even though I don't think this would have saved it).
ZLC Controller reported incorrectly sequencing aircraft resulted in an operational error.