Narrative:

I intended to climb mdt X to 15000'. 15000' was entered in data base, however mdt X was cleared to 16000' inadvertently and was not caught by myself or assistant controller. Traffic was called to mdt X, conflicting traffic at 16000' off his left side. Pilot did not question his assigned altitude after traffic called. Sep was lost after aircraft were past each other. 4 mi and 600' vertical was the closest they got.

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Original NASA ASRS Text

Title: ACFT WAS ISSUED A CLIMB BY MISTAKE TO AN OCCUPIED ALT RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: I INTENDED TO CLB MDT X TO 15000'. 15000' WAS ENTERED IN DATA BASE, HOWEVER MDT X WAS CLRED TO 16000' INADVERTENTLY AND WAS NOT CAUGHT BY MYSELF OR ASSISTANT CTLR. TFC WAS CALLED TO MDT X, CONFLICTING TFC AT 16000' OFF HIS L SIDE. PLT DID NOT QUESTION HIS ASSIGNED ALT AFTER TFC CALLED. SEP WAS LOST AFTER ACFT WERE PAST EACH OTHER. 4 MI AND 600' VERTICAL WAS THE CLOSEST THEY GOT.

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.