Widebody; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 22.0
Confusion; Communication Breakdown; Distraction; Workload
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Environment - Non Weather Related; Human Factors; Procedure
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.
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.
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.