Narrative:

While in cruise at FL380 the ride began to deteriorate so I asked ATC for FL360. ATC said there was traffic to the east at FL360 and we would have to take a turn off track for FL360. I responded that we would accept a heading in order to get the descent. We were given a heading 180 and a speed. Soon after I heard 'flight XXXX descend FL360'; I read back the clearance and we began a descent. During descent through FL376 we received an RA for an aircraft at 12 o'clock opposite direction at FL370. We quickly located the aircraft visually and began a turn to the left. Almost simultaneously the RA became a TA and ordered a climb. We complied with the TA; climbing to FL380. I had visual contact with the traffic at all times. During the event ATC commanded a turn to 090 and his climb/descent command was unclear. I responded 'heading 090 and climbing FL380' to comply with the TA command. Once stable at FL380; we were given direct and a descent to FL360. I queried ATC as to who the descent to FL360 had been for and he responded 'flight xyxy'. I would say that expectation bias played a role in this event. We had asked for FL360 and had been given a heading by ATC in expectation of a descent clearance. When I heard 'flight XXXX descend FL360'; that was exactly what I had expected to hear. My attention initially during the descent was on the aircraft that had originally been given as a conflict to the east at FL360; this aircraft was the reason we were given the 180 heading. This aircraft was now well behind us and off to the west. Hence I was not expecting traffic at 12 o'clock.in future I will be sure to have more of a 'big picture' understanding of the traffic environment before accepting clearances. I feel like we did a good job of responding to the threat during a difficult maneuver at high altitude. Our CRM was good and the threat of collision was quickly and safely removed.

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Original NASA ASRS Text

Title: A321 flight crew reported an airborne conflict after taking a call that was meant for another aircraft.

Narrative: While in cruise at FL380 the ride began to deteriorate so I asked ATC for FL360. ATC said there was traffic to the east at FL360 and we would have to take a turn off track for FL360. I responded that we would accept a heading in order to get the descent. We were given a HDG 180 and a speed. Soon after I heard 'Flight XXXX descend FL360'; I read back the clearance and we began a descent. During descent through FL376 we received an RA for an aircraft at 12 o'clock opposite direction at FL370. We quickly located the aircraft visually and began a turn to the left. Almost simultaneously the RA became a TA and ordered a climb. We complied with the TA; climbing to FL380. I had visual contact with the traffic at all times. During the event ATC commanded a turn to 090 and his climb/descent command was unclear. I responded 'HDG 090 and climbing FL380' to comply with the TA command. Once stable at FL380; we were given direct and a descent to FL360. I queried ATC as to who the descent to FL360 had been for and he responded 'Flight XYXY'. I would say that expectation bias played a role in this event. We had asked for FL360 and had been given a heading by ATC in expectation of a descent clearance. When I heard 'Flight XXXX descend FL360'; that was exactly what I had expected to hear. My attention initially during the descent was on the aircraft that had originally been given as a conflict to the east at FL360; this aircraft was the reason we were given the 180 HDG. This aircraft was now well behind us and off to the west. Hence I was not expecting traffic at 12 o'clock.In future I will be sure to have more of a 'big picture' understanding of the traffic environment before accepting clearances. I feel like we did a good job of responding to the threat during a difficult maneuver at high altitude. Our CRM was good and the threat of collision was quickly and safely removed.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.