Narrative:

I was providing radar OJT to a student on his first radar sector. The student was approximately 1/2 way through the # of hours permitted on the sector. The student vectored small transport X to clear the route of cpr Y. Descending to ubg after clearing other traffic he assigned an altitude above small transport X. I advised the student that he had more than 3 mi. (We were single site adapted within 40 mi of the radar.) the student assigned cpr Y 10000', the same altitude as small aircraft X. I didn't realize that the student had cleared small transport X direct ubg also. When I noticed the converging headings I questioned the student of the heading and told him to turn small transport X to 330 degrees, but it was too late to avoid loss of sep. I did not hear the transmission when he reclred small transport X. Slow traffic and relaxed atmosphere and the sense that he had it under control led me to believe it was working. Supplemental information from acn 150184: cpr Y, en route to hio, was overtaking small transport X en route to pdx. Small transport X was vectored to the west to provide spacing for cpr Y to pas by. When in my opinion the aircraft were not going to have standard sep I turned small transport X back to pdx. My intend was to appreq 110 reference small transport X at 10000' with pdx. My trner at the time pointed out that the aircraft were in a 3 mi area and the aircraft were 3 mi apart at the time. Therefore, I descended cpr Y to 10000' and reduced the aircraft to 250 KTS to meet the LOA.

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Original NASA ASRS Text

Title: SMT X HAD LESS THAN STANDARD SEPARATION FROM CPR Y. SYSTEM ERROR.

Narrative: I WAS PROVIDING RADAR OJT TO A STUDENT ON HIS FIRST RADAR SECTOR. THE STUDENT WAS APPROX 1/2 WAY THROUGH THE # OF HRS PERMITTED ON THE SECTOR. THE STUDENT VECTORED SMT X TO CLR THE RTE OF CPR Y. DSNDING TO UBG AFTER CLRING OTHER TFC HE ASSIGNED AN ALT ABOVE SMT X. I ADVISED THE STUDENT THAT HE HAD MORE THAN 3 MI. (WE WERE SINGLE SITE ADAPTED WITHIN 40 MI OF THE RADAR.) THE STUDENT ASSIGNED CPR Y 10000', THE SAME ALT AS SMA X. I DIDN'T REALIZE THAT THE STUDENT HAD CLRED SMT X DIRECT UBG ALSO. WHEN I NOTICED THE CONVERGING HDGS I QUESTIONED THE STUDENT OF THE HDG AND TOLD HIM TO TURN SMT X TO 330 DEGS, BUT IT WAS TOO LATE TO AVOID LOSS OF SEP. I DID NOT HEAR THE XMISSION WHEN HE RECLRED SMT X. SLOW TFC AND RELAXED ATMOSPHERE AND THE SENSE THAT HE HAD IT UNDER CTL LED ME TO BELIEVE IT WAS WORKING. SUPPLEMENTAL INFO FROM ACN 150184: CPR Y, ENRTE TO HIO, WAS OVERTAKING SMT X ENRTE TO PDX. SMT X WAS VECTORED TO THE W TO PROVIDE SPACING FOR CPR Y TO PAS BY. WHEN IN MY OPINION THE ACFT WERE NOT GOING TO HAVE STANDARD SEP I TURNED SMT X BACK TO PDX. MY INTEND WAS TO APPREQ 110 REF SMT X AT 10000' WITH PDX. MY TRNER AT THE TIME POINTED OUT THAT THE ACFT WERE IN A 3 MI AREA AND THE ACFT WERE 3 MI APART AT THE TIME. THEREFORE, I DSNDED CPR Y TO 10000' AND REDUCED THE ACFT TO 250 KTS TO MEET THE LOA.

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.