Narrative:

It was near the end of my shift; I was being told by the controller in charge (controller in charge) that the sector would be going red for about 20 minutes and was being asked if I wanted to keep a d-side (assist controller) or split out the upper portion of my airspace. About the same time; aircraft X was checking on climbing out of denver. I issued aircraft X a clearance to 37000 feet after doing a quick scan. I then responded to the controller in charge that I would rather just keep a d-side. My d-side then brought my attention to the fact that aircraft X was in conflict with aircraft Y level at 34000 feet but had several minutes to fix the conflict.I issued an amended clearance to aircraft X to maintain 33000 feet. About the same time I was being asked if I wanted a break. I told the controller in charge that I would rather stay on position until I was no longer needed in the area. Several more people were coming in and there was a lot of distractions with my d-side being relieved and also general discussion in the area about the new break board and how to work it. Aircraft X was observed climbing through his assigned altitude and creating a ca with aircraft Y. I issued a 20 degree left turn to aircraft X; told him to maintain 33000 feet and issued a traffic call. Aircraft X read back the clearance but reported they were at 34000 feet and would descend back down to 33000 feet. I then told aircraft Y to turn 20 degrees left. About 5 seconds later; aircraft X reported they were responding to an RA and they were in a climb. I asked aircraft X to report when they were done with the RA. Aircraft X reported level at FL350 right at 5 miles from aircraft Y and I then issued both aircraft clearances back on route.I believe that I was being asked to make several decisions at once while also trying to work traffic and with the line change with a new crew coming in; there were too many distractions that caused me to miss a readback from aircraft X.

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Original NASA ASRS Text

Title: ZDV Controller missed an incorrect altitude readback from an aircraft due to distractions in the work area. The aircraft climbed into a conflict with opposite direction traffic.

Narrative: It was near the end of my shift; I was being told by the Controller In Charge (CIC) that the sector would be going red for about 20 minutes and was being asked if I wanted to keep a D-side (Assist Controller) or split out the upper portion of my airspace. About the same time; Aircraft X was checking on climbing out of Denver. I issued Aircraft X a clearance to 37000 feet after doing a quick scan. I then responded to the CIC that I would rather just keep a D-side. My D-side then brought my attention to the fact that Aircraft X was in conflict with Aircraft Y level at 34000 feet but had several minutes to fix the conflict.I issued an amended clearance to Aircraft X to maintain 33000 feet. About the same time I was being asked if I wanted a break. I told the CIC that I would rather stay on position until I was no longer needed in the area. Several more people were coming in and there was a lot of distractions with my D-side being relieved and also general discussion in the area about the new break board and how to work it. Aircraft X was observed climbing through his assigned altitude and creating a CA with Aircraft Y. I issued a 20 degree left turn to Aircraft X; told him to maintain 33000 feet and issued a traffic call. Aircraft X read back the clearance but reported they were at 34000 feet and would descend back down to 33000 feet. I then told Aircraft Y to turn 20 degrees left. About 5 seconds later; Aircraft X reported they were responding to an RA and they were in a climb. I asked Aircraft X to report when they were done with the RA. Aircraft X reported level at FL350 right at 5 miles from Aircraft Y and I then issued both aircraft clearances back on route.I believe that I was being asked to make several decisions at once while also trying to work traffic and with the line change with a new crew coming in; there were too many distractions that caused me to miss a readback from Aircraft X.

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.