Date: 201701
Local time of day: 1801-2400
Location: ZMP.ARTCC, MN
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 ZMP
ATC / advisory: Center ZMP
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Communication Breakdown; Confusion
Second reporter function: Enroute
Anomaly: Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: I was the R-side receiving a break. I had a traffic conflict with Aircraft X level at FL360. Prior to completing the briefing I turned Aircraft X 20 degrees right. The confliction was noted to the next controller and briefing completed. I was informed later that night that a deal was almost had with Aircraft X. I was told that the aircraft was complaining about the time he was on the heading and the next controller told me at that time they appeared to turn back to the left without clearance to do so.They were then turned further to the right; and eventually cleared to FL350. They took the turn; but didn't start out of FL360 for over 50 seconds after the clearance was given. Aircraft X proceeded to go right along the minimum separation; but was never lost. After reviewing the event on Falcon; it appeared the aircraft turned back to the left on their own; and didn't obey an ATC command in a timely manner. This was an unsafe situation caused by a possible pilot deviation and disregard of an ATC clearance.Pilot should be reprimanded for not obeying a clearance. Our job is to separate the traffic; and if aircraft don't obey our commands we cannot effectively do our job.


Second narrative: Aircraft X was given a 20 degree off course vector for an aircraft heading southbound. Aircraft X asked how much longer on this heading. I then told the pilot the computer did not like the heading and that I needed him to turn an additional 10 degrees right. His unprofessional response was Roger. I issued a descent because the aircraft never made the additional turn. I asked if the aircraft was descending. They responded with out of 360 now for 350.' I said probably not going to work. Thanks. I cleared the aircraft back direct to DVC.So what alerted me to the fact that the original heading wasn't going to work is the fact that the pilot on their own started to make a very slow turn back to DVC without ATC clearance. It is visible in the falcon that was made. Compounding to the problem was the fact the pilot did not turn the additional 10 degrees that was needed after he started to turn back towards DVC. Then not descending after given a clearance to descend. At this point I had no way to control that aircraft and everything was resting on a hope and prayer that the two aircraft would not come within 5 miles of each other. I recommend making pilots be held accountable for following ATC clearances and actually use proper phraseology. This guy was impatient and being a jerk and that compromised the safety of the situation at hand. I am sure absolutely nothing will come from this and the pilot won't get any sort of reprimand. Because why should a pilot ever be held accountable?


Synopsis: ZMP Controllers reported of a pilot who did not follow ATC instructions and turned the aircraft to a different heading than what was assigned.