Narrative:

Sector 5; koa runway 35 in use; a CRJ2 departed koa airport headed west bound to hnl climbing to FL220. There were two aircraft following in sequence headed to hnl. I stopped the CRJ2 climb at FL200 so they could level off sooner and pick up speed. The adjacent sector had opposite direction traffic into koa at FL190 with a pilot's discretion to 3;000. When I handed off the CRJ2; there was about 50 miles between the 2 aircraft and the CRJ2 was climbing out of FL180. Both I and the other controller saw the traffic but assumed we would have vertical well before they would became an issue. Meanwhile; I had a A320 inbound to koa on a 180 heading to keep him clear of my departure corridor off koa. Koa tower requested a release for an E135 and I assigned them a 350 heading. When I went back to switch the CRJ2 to sector 4; I noticed his altitude was FL189 and had been there for about 1 minute without changing. It looked as though the CRJ2 had level off on his own. At this time the ca (conflict alert) went off and I told the CRJ2 to verify they were climbing and issued a heading left of course. The sector 4 controller turned his aircraft and instructed them to descend. I'd say the closest proximity was 7-8 miles horizontally. No separation was lost. When the sector 4 controller told the CRJ2 that it looked like he had leveled off at FL190; they said they had experienced light rime ice and had told myself that they would be in a slow climb. This so called conversation never took place and I was never aware of it. Even if it did; leveling off for 1 minute at the wrong altitude for direction of flight is not the same as a slow climb. While all this was going on; the E135 had departed and been radar contact. I noticed their 350 heading looked a little left of course and was a little closer to the A320 on the downwind. So I cleared the E135 direct ebber which is directly to the east (about a 060 heading from the position) to get more spacing and get them on their way. The two aircraft were never in danger of each other; but they did look a little close for comfort. I'd say about 6 miles. Though it should have never been that close; I feel now that my attention was diverted to the situation with the CRJ2; and because of it; everything else was secondary. Recommendation for my part: make sure I watch the aircraft climb all the way to altitude. Also; make a conscious effort to scan the entire sector instead of just focusing only on the one matter. I feel pilots need to understand they cannot just do things on their own without advising ATC of what they are doing.

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Original NASA ASRS Text

Title: HCF Controller described a potential conflict event when they failed to closely observe the climb performance of one of the involved aircraft.

Narrative: Sector 5; KOA Runway 35 in use; a CRJ2 departed KOA airport headed west bound to HNL climbing to FL220. There were two aircraft following in sequence headed to HNL. I stopped the CRJ2 climb at FL200 so they could level off sooner and pick up speed. The adjacent sector had opposite direction traffic into KOA at FL190 with a pilot's discretion to 3;000. When I handed off the CRJ2; there was about 50 miles between the 2 aircraft and the CRJ2 was climbing out of FL180. Both I and the other Controller saw the traffic but assumed we would have vertical well before they would became an issue. Meanwhile; I had a A320 inbound to KOA on a 180 heading to keep him clear of my departure corridor off KOA. KOA Tower requested a release for an E135 and I assigned them a 350 heading. When I went back to switch the CRJ2 to Sector 4; I noticed his altitude was FL189 and had been there for about 1 minute without changing. It looked as though the CRJ2 had level off on his own. At this time the CA (Conflict Alert) went off and I told the CRJ2 to verify they were climbing and issued a heading left of course. The Sector 4 Controller turned his aircraft and instructed them to descend. I'd say the closest proximity was 7-8 miles horizontally. No separation was lost. When the Sector 4 Controller told the CRJ2 that it looked like he had leveled off at FL190; they said they had experienced light rime ice and had told myself that they would be in a slow climb. This so called conversation never took place and I was never aware of it. Even if it did; leveling off for 1 minute at the wrong altitude for direction of flight is not the same as a slow climb. While all this was going on; the E135 had departed and been RADAR contact. I noticed their 350 heading looked a little left of course and was a little closer to the A320 on the downwind. So I cleared the E135 direct EBBER which is directly to the east (about a 060 heading from the position) to get more spacing and get them on their way. The two aircraft were never in danger of each other; but they did look a little close for comfort. I'd say about 6 miles. Though it should have never been that close; I feel now that my attention was diverted to the situation with the CRJ2; and because of it; everything else was secondary. Recommendation for my part: make sure I watch the aircraft climb all the way to altitude. Also; make a conscious effort to scan the entire sector instead of just focusing only on the one matter. I feel pilots need to understand they cannot just do things on their own without advising ATC of what they are doing.

Data retrieved from NASA's ASRS site as of April 2012 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.