Date: 201603
Local time of day: 1801-2400
Location: ZID.ARTCC, IN
Light: Night
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZID
ATC / advisory: Center ZID
Second aircraft: Medium Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Developmental
Human factors: Confusion; Communication Breakdown; Distraction; Workload; Situational Awareness
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance
Contributing factors: Weather; Human Factors; Procedure
Primary problem: Weather

Narrative: Aircraft X had been turned 10 degrees left upon entering our airspace; and was then cleared back on course. The radar controller had taken the handoff on Aircraft Y; level at FL350 and requesting FL370; while still on the opposite side of the sector from Aircraft X. The radar controller had tried to contact Aircraft Y to climb at least twice; but the frequency change still had not come from the sector below; so the aircraft remained level at FL350 for approximately 3 minutes since the handoff was taken. In those three minutes; Aircraft X had requested deviations for the weather; and was cleared to deviate left of course; and direct to MCI when able. Aircraft Y had finally checked on; and was initially climbed to FL370. We had then seen traffic coming out of ZAU at FL370 that would have been in confliction with Aircraft Y; so the radar controller amended the altitude to FL360. At this time; we had noticed Aircraft X making a right turn; which was unexpected because had had been cleared for left deviations. Seeing that this was now turning right into Aircraft Y; the radar controller issued a 10 degree left turn to Aircraft X; who then responded that he was unable to make the turn due to weather. The radar controller then cleared Aircraft Y to DORET; which was a left turn; and the pilot accepted the turn. After a few radar updates and the aircraft still had not made the turn; the radar controller told the pilot to start the turn to DORET; and the pilot had said that the turn put would them right into the weather. We were not displaying any precipitation in that vicinity. The sector below us had said we can take Aircraft X down to FL350; so the R-side issued the descent and a 20 degree left turn. Standard separation was lost; and after both aircraft were no longer a factor with each other; they were cleared back on course. Had the Aircraft Y pilot notified us that he did not want to turn to DORET when they were initially cleared; alternative actions could have perhaps been taken earlier. Also; the pilot of Aircraft X could have told us initially when he was given clearance to deviate left that he would rather have right deviations.




Synopsis: ZID Controller reported a loss of separation due to an aircraft deviating for weather. The aircraft was approved for left of course; but turned right of course and lost separation with another aircraft.