Narrative:

DA50 checked on txk-hi frequency climbing to FL230 requesting FL370. I was working txk-hi radar position and climbed DA50 to FL370. DA50 had departed dfw and was to overfly txk J42. At XA26Z aircraft Y checked on frequency level at FL340. Aircraft Y was entering the northeast corner of the sector flying over txk.C2Y.sat. I say that a restr would be necessary to ensure DA50 would get above aircraft Y. I asked if DA50 could be above FL350 within 3 mins. I had calculated that separation would be lost in about 4 mins. DA50 replied that he could be above FL350 within 3 mins. I then issued the restr to DA50 to be at FL350 within 3 mins or less. DA50 read back that he would be level at FL350 in 3 mins or less at XA28:40. At about XA31Z; I realized that DA50 would not make the restr and turned DA50 20 degrees right. I then turned aircraft Y 20 degrees right. I then turned DA50 further right to heading 100 degrees. Then I turned aircraft Y to heading 300 degrees. At XA32:13 I told DA50 to report reaching FL350. At XA32:17 separation was lost. At XA32:29 DA50 reported level. I then cleared each aircraft back on course. DA50 was approximately 50 seconds late meeting the restr. Had DA50 met the restr; no error would have occurred.

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Original NASA ASRS Text

Title: ZFW CTLR EXPERIENCED OPERROR WHEN ESTIMATED CLB RATES; TIME FACTORS AND TURNS WERE MISJUDGED AND SEPARATION WAS LOST AT FL340.

Narrative: DA50 CHKED ON TXK-HI FREQ CLBING TO FL230 REQUESTING FL370. I WAS WORKING TXK-HI RADAR POS AND CLBED DA50 TO FL370. DA50 HAD DEPARTED DFW AND WAS TO OVERFLY TXK J42. AT XA26Z ACFT Y CHKED ON FREQ LEVEL AT FL340. ACFT Y WAS ENTERING THE NE CORNER OF THE SECTOR FLYING OVER TXK.C2Y.SAT. I SAY THAT A RESTR WOULD BE NECESSARY TO ENSURE DA50 WOULD GET ABOVE ACFT Y. I ASKED IF DA50 COULD BE ABOVE FL350 WITHIN 3 MINS. I HAD CALCULATED THAT SEPARATION WOULD BE LOST IN ABOUT 4 MINS. DA50 REPLIED THAT HE COULD BE ABOVE FL350 WITHIN 3 MINS. I THEN ISSUED THE RESTR TO DA50 TO BE AT FL350 WITHIN 3 MINS OR LESS. DA50 READ BACK THAT HE WOULD BE LEVEL AT FL350 IN 3 MINS OR LESS AT XA28:40. AT ABOUT XA31Z; I REALIZED THAT DA50 WOULD NOT MAKE THE RESTR AND TURNED DA50 20 DEGS R. I THEN TURNED ACFT Y 20 DEGS R. I THEN TURNED DA50 FURTHER R TO HDG 100 DEGS. THEN I TURNED ACFT Y TO HDG 300 DEGS. AT XA32:13 I TOLD DA50 TO RPT REACHING FL350. AT XA32:17 SEPARATION WAS LOST. AT XA32:29 DA50 RPTED LEVEL. I THEN CLRED EACH ACFT BACK ON COURSE. DA50 WAS APPROX 50 SECONDS LATE MEETING THE RESTR. HAD DA50 MET THE RESTR; NO ERROR WOULD HAVE OCCURRED.

Data retrieved from NASA's ASRS site as of January 2009 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.