Date: 201512
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Light: Night
Aircraft: Widebody; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Communication Breakdown; Distraction; Workload
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Air Traffic Control; Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Contributing factors: Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Human Factors

Narrative: I was working [Aircraft X] climbing westbound. The aircraft had been shortcut direct to his destination so he was climbing on the boundary of 3 different airspaces. [Aircraft X] had climbed to FL280. I verbally coordinated with Sector 36 control to continue climbing [Aircraft X]. In the meantime; I had accepted radar contact from sector 36 on [Aircraft Y] descending northbound to FL 290. As I was working at the radar scope adjacent to sector 36; I verbally asked the controller still working the [Aircraft Y] to stop him at FL310. I then climbed the [Aircraft X] to FL300. In hindsight; the reply and approval from sector 36 was an additional acknowledgment of his permission for me to climb [Aircraft X]. Not an acknowledgment to stop [Aircraft Y]. The controller at sector 36 stated later that he though I was already talking to the [Aircraft Y]. When I realized that [Aircraft Y] had not been stopped at FL310; I instructed [Aircraft X] to stop his climb and descend to FL290. At that time [Aircraft X] responded and stated that he was also responding to a TCAS resolution advisory. I told the [Aircraft X] about the traffic and the controller at sector 36 climbed the [Aircraft Y]. I believe there was no loss of separation.Better communication between the 2 controllers would have prevented the event. The vagueness of the requests and replies made it hard to determine exactly what was being requested and what was approved.


Second narrative: I was working [Aircraft Y]. I issued a control instruction for the aircraft to be level at FL290 at the boundary of the next airspace. After I had issued this clearance I saw the heavy approaching my airspace from the east at the north end of the sector. The aircraft auto flashed at FL280; and the controller at ZZZ said what I thought was 'Point out' [Aircraft X]. I said approved; and flashed the aircraft back at ZZZ. In the meantime; ZZZ had taken radar on [Aircraft Y] and changed the data block to an interim of FL310 rather than FL290. What the R side at ZZZ had told me was to stop [Aircraft Y] at FL310. I never heard the request and never issued the instruction. When the aircraft were about a minute apart I noticed the datablock had been changed and I immediately realized that [Aircraft Y] did not have the correct altitude. At this point [Aircraft Y] was out of FL317 and descending; and [Aircraft X] was level at FL300. I asked [Aircraft Y] to say altitude to which they responded they were responding to an RA. I issued a traffic alert to [Aircraft Y]; and let them respond to the Resolution Advisory (RA).There was no loss of separation between the two aircraft. The ZZZ controller and I should have been more aware of what each other's plans were. There was a breakdown in coordination; and I was unaware of the others plan.


Synopsis: Two ARTCC Controllers and four air carrier pilots report their perspectives after two ATC Controllers' confusion required one air carrier climbing to take evasive action while a descending air carrier took opposite direction evasive action. TCAS RA alerts were factors.