Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors
Air Carrier X was at FL380 landing CMH. Air Carrier Y was at FL360 landing PHX; routed under Air Carrier X. I cleared Air Carrier Y direct VHP to keep him north of Air Carrier X and turned Air Carrier X 15 left (south) for his descent. After getting Air Carrier X clear of Air Carrier Y; I cleared Air Carrier X direct AIR which should have kept him south of Air Carrier Y and descended Air Carrier X to FL350. Air Carrier X turned northwest instead of west and headed back into Air Carrier Y. I then turned Air Carrier X 10 left and Air Carrier Y 10 right but needed more and turned Air Carrier X an additional 15 left. [Should have] assigned Air Carrier X a heading until below Air Carrier Y instead of a Direct route.
ZOB Controller described a conflict event when issuing a 'direct' clearance when a more positive method of separation should have been used.