Narrative:

Air carrier Y wbound at FL310 corp X eastbound, heads up with air carrier Y. Corp X climbing through air carrier Y. Approximately 4 mins before incident, I asked pilot of corp X his rate of climb. He said 2000 FPM. In my professional opinion, I had plenty of sep with room to spare. I went about other ATC duties. Looked back at corp X. He appeared not to be climbing well. I asked pilot if he could be out of FL330 in 1 min. He said yes. I told him I needed him out of FL330 in 30 seconds. He said he didn't know if he could do it or not. I turned him 45 degrees right. I turned air carrier Y 45 degrees right. C/a did not go off until loss of sep had already occurred. I asked corp X to verify out of FL330. He said no, that he was out of FL325. I feel this happened for many reasons: 1) corp X not climbing at 2000 FPM as pilot said he was. 2) inadequate staffing. 3) C/a not going off until after loss of sep. 4) extensive amounts of overtime. 5) being forced into the high/low concept. 6) not proficient on high altitude sectors. 7) not comfortable the least bit with high altitude traffic. 8) working low altitude traffic 1 day, high the next. This is a totally different type of ATC; different ranges, speeds and types of aircraft. This is dangerous. I will never be as good of a controller as when I worked low altitude traffic only! I was a specialist. Now I am a general practitioner. I am no longer as proficient on low altitude sectors as I was and probably never will be.

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Original NASA ASRS Text

Title: CORP ACFT CLIMBED THROUGH ALT ASSIGNED TO ANOTHER ACFT.

Narrative: ACR Y WBOUND AT FL310 CORP X EBND, HEADS UP WITH ACR Y. CORP X CLBING THROUGH ACR Y. APPROX 4 MINS BEFORE INCIDENT, I ASKED PLT OF CORP X HIS RATE OF CLB. HE SAID 2000 FPM. IN MY PROFESSIONAL OPINION, I HAD PLENTY OF SEP WITH ROOM TO SPARE. I WENT ABOUT OTHER ATC DUTIES. LOOKED BACK AT CORP X. HE APPEARED NOT TO BE CLBING WELL. I ASKED PLT IF HE COULD BE OUT OF FL330 IN 1 MIN. HE SAID YES. I TOLD HIM I NEEDED HIM OUT OF FL330 IN 30 SECS. HE SAID HE DIDN'T KNOW IF HE COULD DO IT OR NOT. I TURNED HIM 45 DEGS RIGHT. I TURNED ACR Y 45 DEGS RIGHT. C/A DID NOT GO OFF UNTIL LOSS OF SEP HAD ALREADY OCCURRED. I ASKED CORP X TO VERIFY OUT OF FL330. HE SAID NO, THAT HE WAS OUT OF FL325. I FEEL THIS HAPPENED FOR MANY REASONS: 1) CORP X NOT CLBING AT 2000 FPM AS PLT SAID HE WAS. 2) INADEQUATE STAFFING. 3) C/A NOT GOING OFF UNTIL AFTER LOSS OF SEP. 4) EXTENSIVE AMOUNTS OF OVERTIME. 5) BEING FORCED INTO THE HIGH/LOW CONCEPT. 6) NOT PROFICIENT ON HIGH ALT SECTORS. 7) NOT COMFORTABLE THE LEAST BIT WITH HIGH ALT TFC. 8) WORKING LOW ALT TFC 1 DAY, HIGH THE NEXT. THIS IS A TOTALLY DIFFERENT TYPE OF ATC; DIFFERENT RANGES, SPDS AND TYPES OF ACFT. THIS IS DANGEROUS. I WILL NEVER BE AS GOOD OF A CTLR AS WHEN I WORKED LOW ALT TFC ONLY! I WAS A SPECIALIST. NOW I AM A GENERAL PRACTITIONER. I AM NO LONGER AS PROFICIENT ON LOW ALT SECTORS AS I WAS AND PROBABLY NEVER WILL BE.

Data retrieved from NASA's ASRS site as of August 2007 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.