Narrative:

I took over the radar position in the morning. Aircraft X coming from sector 37 airspace was climbing to 31;000 feet as a final. He was predicted to be in conflict with aircraft Y at 31;000 feet. The previous radar assist issued clearance to stop aircraft X at 30;000 feet for aircraft Y at 31;000 feet going to las VOR then east bound. Aircraft X was a slow climber coming from sector 37 just out of 27;000 feet when he checked in climbing to 30;000 feet.I cleared aircraft Y direct gck to have them pass faster so I can climb aircraft X ; once they clear laterally. As the targets were merging; 7-8 miles away from each other; I called traffic for aircraft X to expect higher once clear of aircraft Y . I told him to maintain 3;000 feet. But his mode C was indicating 30;100 feet and slowing climbing. He acknowledged to maintain 30;000 feet but was out of 30;300 feet and descending back down. They were about 6 miles laterally and converging. I turned aircraft Y 20 degrees left and aircraft X 20 degrees right but they were within 5 miles of each other. Aircraft X came within 3-4 miles of aircraft Y and around 800 feet. Once they established vertical separation; I cleared both back on course. I should have re-verified that aircraft X was maintaining 30;000 feet.

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Original NASA ASRS Text

Title: ZLA Center Controller receiving a handoff told an adjacent sector to stop the aircraft's climb for converging traffic. The Controller making the handoff was distracted by other tasks and forgot to comply with the instruction causing less than required separation with the converging traffic.

Narrative: I took over the Radar position in the morning. Aircraft X coming from sector 37 airspace was climbing to 31;000 feet as a final. He was predicted to be in conflict with Aircraft Y at 31;000 feet. The previous Radar Assist issued clearance to stop Aircraft X at 30;000 feet for Aircraft Y at 31;000 feet going to LAS VOR then east bound. Aircraft X was a slow climber coming from sector 37 just out of 27;000 feet when he checked in climbing to 30;000 feet.I cleared Aircraft Y direct GCK to have them pass faster so I can climb Aircraft X ; once they clear laterally. As the targets were merging; 7-8 miles away from each other; I called traffic for Aircraft X to expect higher once clear of Aircraft Y . I told him to maintain 3;000 feet. But his Mode C was indicating 30;100 feet and slowing climbing. He acknowledged to maintain 30;000 feet but was out of 30;300 feet and descending back down. They were about 6 miles laterally and converging. I turned Aircraft Y 20 degrees left and Aircraft X 20 degrees right but they were within 5 miles of each other. Aircraft X came within 3-4 miles of Aircraft Y and around 800 feet. Once they established vertical separation; I cleared both back on course. I should have re-verified that Aircraft X was maintaining 30;000 feet.

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.