Date: 201910
Local time of day: 1201-1800
Location: ZMP.ARTCC, MN
Light: Daylight
Aircraft: B757 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZMP
ATC / advisory: Center ZMP
Second aircraft: B757 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Supervisor / CIC; Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Workload; Situational Awareness; Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance
Contributing factors: Procedure; Human Factors; Airspace Structure; Company Policy
Primary problem: Company Policy

Narrative: I was the Controller in Charge when the Radar team at Sector 42 called me over to witness one of the more atrocious examples of a [airborne conflict] I've seen in a while. Aircraft X; Aircraft Y and Aircraft Z were all at 35;000 ft. on converging courses. Denver Sector 8 had assigned Aircraft Y present heading to 'go behind' Aircraft X. The problem was that Aircraft Z who was south of Aircraft Y was going to be closer to Aircraft X. The winds were out of the southwest at about 100 plus kts. making Aircraft Y and Aircraft Z faster than Aircraft X. Denver 8 called to advise our controllers that he had assigned Aircraft Y present heading and that Aircraft Z was assigned 10 left turn. The Sector 42 D side (Radar Assist) explained to Denver 8 that his plan wasn't going to work and that they wanted him to take Aircraft Y up to 37;000 ft. or down to 33;000 ft. Denver 8 immediately became argumentative and actually laughed at our D side! After advising the Denver 8 Controller that that's what we wanted him to do he said; 'Okay.' Seconds later Aircraft Y checked on our frequency still level at 35;000 ft. Denver 8 refused to issue a climb or descent clearance. As Aircraft Y checks on our frequency Denver 8 calls and makes an excuse that because we took the handoff he didn't know how to coordinate and assign an altitude to Aircraft Y. The Sector 42 Radar Controller asked Aircraft Y if he was able FL370 to which he replies; 'No; too heavy.' As soon as Aircraft Z checked on the Radar Controller turned him an additional 15 degrees left which put him in conflict with Aircraft Y. The D side coordinated with the sector below to descend Aircraft Y to 33;000 ft. The Radar controller changed his mind and turned Aircraft Y 20 degrees left to parallel Aircraft Z.If the Radar Controller had not taken evasive action; separation would have been lost less than one minute inside our airspace. In this case the D side and Sector 42 told Denver 8 exactly what to do and gave him two options. Denver 8 did nothing and shipped the aircraft that we told him to move. As a result we were left scrambling in an effort to coordinate and avoid losing separation with 3 aircraft all within one minute of having communications. The Denver 8 controller and his Supervisors need to be held accountable for disobeying clearance instructions.




Synopsis: A Center Controller reported a recurring problem of an adjacent Center sector handing them off aircraft on converging heading at the same altitude; causing an airborne conflict.