Narrative:

Aircraft #1 was on initial climb out after departing sbn. Aircraft #2 was level at 15000 ft and inbound to fwa. Aircraft was given a 150 degree heading for his climb to clear additional traffic at 13000 ft. Instructor then gave aircraft #1 a 110 degree heading so as to establish horizontal separation more quickly. Aircraft #2 was on approximately 130 degree heading and was direct to destination. After clearing previous traffic at 13000 ft, I issued a climb to FL210 to aircraft #1 but failed to issue an on course or parallel heading to insure separation from aircraft #2. I then issued a descent to aircraft #2 to 11000 ft while still on an unassigned heading (direct destination). Instructor did not hear part or all of the above. Upon seeing altitude information in data blocks, instructor took corrective action, but separation was lost.

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Original NASA ASRS Text

Title: ZAU INSTRUCTOR OVERRIDES TRAINEE AND TAKES ACTION TO SEPARATE A CLBING CARJ FROM A DSNDING SF34 WHEN OBSERVING A DEVELOPING CONFLICT.

Narrative: ACFT #1 WAS ON INITIAL CLBOUT AFTER DEPARTING SBN. ACFT #2 WAS LEVEL AT 15000 FT AND INBOUND TO FWA. ACFT WAS GIVEN A 150 DEG HDG FOR HIS CLB TO CLR ADDITIONAL TFC AT 13000 FT. INSTRUCTOR THEN GAVE ACFT #1 A 110 DEG HDG SO AS TO ESTABLISH HORIZ SEPARATION MORE QUICKLY. ACFT #2 WAS ON APPROX 130 DEG HDG AND WAS DIRECT TO DEST. AFTER CLRING PREVIOUS TFC AT 13000 FT, I ISSUED A CLB TO FL210 TO ACFT #1 BUT FAILED TO ISSUE AN ON COURSE OR PARALLEL HDG TO INSURE SEPARATION FROM ACFT #2. I THEN ISSUED A DSCNT TO ACFT #2 TO 11000 FT WHILE STILL ON AN UNASSIGNED HDG (DIRECT DEST). INSTRUCTOR DID NOT HEAR PART OR ALL OF THE ABOVE. UPON SEEING ALT INFO IN DATA BLOCKS, INSTRUCTOR TOOK CORRECTIVE ACTION, BUT SEPARATION WAS LOST.

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.