Narrative:

I was working a combined right/D position, controling MTR upt traffic in a MOA/atacc (chd MOA-1 atacc 2-3). MTR was a x-country, returning to chd and it was at FL330 proceeding gbn direct to sonra (approach fix for chd). Medium large transport, from dfw to sna at FL310, was on a direct route from elp to bxk. The sector I was working had an altitude shelf where FL230 through FL280 belongs to the sector I was working (sector 40); FL290 through FL310 belongs to an en route high sector (sector 91) and FL330 and above belongs to an en route ultra-high sector (sector 65). At the time of the incident I had 2 x-country aircraft converging at the sonra DME fix at FL330. MTR requested lower altitude at about the srp 135032 fix, and, failing to grasp the fact that he was still within the confines of the shelved airspace, and concerned with the potential confliction at the sonra DME fix, I issued descent clearance to MTR to maintain FL260. The conflict alert function activated, and realizing my mistake, I cleared MTR to climb immediately back to FL330. A loss of standard separation occurred between the MTR and the medium large transport. (En route westbound at FL310). The sector I was working had light to moderate traffic, and moderate complexity. I did not notice the limited data block on the medium large transport due to the congestion of targets in the area. (I was watching surface to infinity).

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Original NASA ASRS Text

Title: STANDARD SEPARATION WAS LOST WHEN AN ACFT WAS DESCENDED PREMATURELY AND IT CONFLICTED WITH AN ENROUTE ACFT AT ITS ASSIGNED ALT.

Narrative: I WAS WORKING A COMBINED R/D POS, CTLING MTR UPT TFC IN A MOA/ATACC (CHD MOA-1 ATACC 2-3). MTR WAS A X-COUNTRY, RETURNING TO CHD AND IT WAS AT FL330 PROCEEDING GBN DIRECT TO SONRA (APCH FIX FOR CHD). MLG, FROM DFW TO SNA AT FL310, WAS ON A DIRECT RTE FROM ELP TO BXK. THE SECTOR I WAS WORKING HAD AN ALT SHELF WHERE FL230 THROUGH FL280 BELONGS TO THE SECTOR I WAS WORKING (SECTOR 40); FL290 THROUGH FL310 BELONGS TO AN ENRTE HIGH SECTOR (SECTOR 91) AND FL330 AND ABOVE BELONGS TO AN ENRTE ULTRA-HIGH SECTOR (SECTOR 65). AT THE TIME OF THE INCIDENT I HAD 2 X-COUNTRY ACFT CONVERGING AT THE SONRA DME FIX AT FL330. MTR REQUESTED LOWER ALT AT ABOUT THE SRP 135032 FIX, AND, FAILING TO GRASP THE FACT THAT HE WAS STILL WITHIN THE CONFINES OF THE SHELVED AIRSPACE, AND CONCERNED WITH THE POTENTIAL CONFLICTION AT THE SONRA DME FIX, I ISSUED DSNT CLRNC TO MTR TO MAINTAIN FL260. THE CONFLICT ALERT FUNCTION ACTIVATED, AND REALIZING MY MISTAKE, I CLRED MTR TO CLB IMMEDIATELY BACK TO FL330. A LOSS OF STANDARD SEPARATION OCCURRED BTWN THE MTR AND THE MLG. (ENRTE WBND AT FL310). THE SECTOR I WAS WORKING HAD LIGHT TO MODERATE TFC, AND MODERATE COMPLEXITY. I DID NOT NOTICE THE LIMITED DATA BLOCK ON THE MLG DUE TO THE CONGESTION OF TARGETS IN THE AREA. (I WAS WATCHING SURFACE TO INFINITY).

Data retrieved from NASA's ASRS site as of July 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.