Narrative:

It was necessary to descend aircraft #1 from FL350 to FL310. I issued a descent clearance knowing that I would need to vector at least 1 of the aircraft. I immediately turned aircraft #2 15 degrees left to get him started in the direction to go behind aircraft #1. I believe that aircraft #2 picked up speed at this point. I then turned aircraft #1 15 degrees left. Eventually I turned aircraft #1 to a 190 degree heading (approximately 60-70 degrees off the original heading). I turned aircraft #2 to a 90 degree heading (approximately 80 degrees off the original heading). The aircraft passed with 4 NM separation at the closest point. I believe the incident occurred primarily due to an error in judgement. I believe that I should have waited to descend aircraft #1 until he had passed over aircraft #2, but I was also cognizant of the fact that, in order to do that, I would need to coordinate with the super high sector to inform them that I would not be descending the aircraft immediately. I also needed to correct the filed route on aircraft #1 and I felt that in order to fulfill all of the requirements, I needed to start the aircraft down and make the situation work. Unfortunately, the 5 NM separation was not maintained.

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Original NASA ASRS Text

Title: LTSS WHEN MIL C21 WAS DSNDED THROUGH THE ALT OF A CPR DA20 WITH LESS THAN THE REQUIRED 5 MI SEPARATION. OPERROR.

Narrative: IT WAS NECESSARY TO DSND ACFT #1 FROM FL350 TO FL310. I ISSUED A DSCNT CLRNC KNOWING THAT I WOULD NEED TO VECTOR AT LEAST 1 OF THE ACFT. I IMMEDIATELY TURNED ACFT #2 15 DEGS L TO GET HIM STARTED IN THE DIRECTION TO GO BEHIND ACFT #1. I BELIEVE THAT ACFT #2 PICKED UP SPD AT THIS POINT. I THEN TURNED ACFT #1 15 DEGS L. EVENTUALLY I TURNED ACFT #1 TO A 190 DEG HDG (APPROX 60-70 DEGS OFF THE ORIGINAL HDG). I TURNED ACFT #2 TO A 90 DEG HDG (APPROX 80 DEGS OFF THE ORIGINAL HDG). THE ACFT PASSED WITH 4 NM SEPARATION AT THE CLOSEST POINT. I BELIEVE THE INCIDENT OCCURRED PRIMARILY DUE TO AN ERROR IN JUDGEMENT. I BELIEVE THAT I SHOULD HAVE WAITED TO DSND ACFT #1 UNTIL HE HAD PASSED OVER ACFT #2, BUT I WAS ALSO COGNIZANT OF THE FACT THAT, IN ORDER TO DO THAT, I WOULD NEED TO COORDINATE WITH THE SUPER HIGH SECTOR TO INFORM THEM THAT I WOULD NOT BE DSNDING THE ACFT IMMEDIATELY. I ALSO NEEDED TO CORRECT THE FILED RTE ON ACFT #1 AND I FELT THAT IN ORDER TO FULFILL ALL OF THE REQUIREMENTS, I NEEDED TO START THE ACFT DOWN AND MAKE THE SIT WORK. UNFORTUNATELY, THE 5 NM SEPARATION WAS NOT MAINTAINED.

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.