Narrative:

Air carrier X at FL330 cleared to FL280. Air carrier Y at FL310. Aircraft passed within 5 mi lateral with less than 2000' sep vertically. Air carrier X began descent (clearance was pilot discretion) within close proximity to air carrier Y. Controller distraction by complex sep situation at another part of the sector. Controller's attention redirected when pilot of air carrier X reported leaving FL330. Immediate action taken to prevent loss of sep, however aircraft were at speeds and on courses that prevented the controller from preserving 5 mi and/or 2000'. Resulting sep: 4 mi/1200'.

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Original NASA ASRS Text

Title: ACR WAS ISSUED A DESCENT CLRNC THROUGH AN OCCUPIED ALT, RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: ACR X AT FL330 CLRED TO FL280. ACR Y AT FL310. ACFT PASSED WITHIN 5 MI LATERAL WITH LESS THAN 2000' SEP VERTICALLY. ACR X BEGAN DSCNT (CLRNC WAS PLT DISCRETION) WITHIN CLOSE PROX TO ACR Y. CTLR DISTR BY COMPLEX SEP SITUATION AT ANOTHER PART OF THE SECTOR. CTLR'S ATTN REDIRECTED WHEN PLT OF ACR X RPTED LEAVING FL330. IMMEDIATE ACTION TAKEN TO PREVENT LOSS OF SEP, HOWEVER ACFT WERE AT SPDS AND ON COURSES THAT PREVENTED THE CTLR FROM PRESERVING 5 MI AND/OR 2000'. RESULTING SEP: 4 MI/1200'.

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.