Narrative:

Widebody transport X eastbound at FL370. Light transport Y wbound at FL390. The light transport Y requested lower since he was landing at columbus, oh. The controller knew it would be close, but thought the light transport Y could make a good rate down. After 2 radar updates, it became apparent that vertical sep would not exist and avoidance vectors were issued to both aircraft. It was simply an error in judgement. Different pilots fly the same aircraft differently, and in the situation I felt it should have worked. Workload was heavy, but not unmanageable. Callback conversation with reporter revealed the following: reporter specified type air carrier aircraft as widebody transport. Computer only had one hit at 4.3 NM and showed 1600'. Considered a minor infringement. Traffic advisory was given both aircraft and light transport had traffic information before descent clearance was given. Light transport was asked if he could be level at FL350 in 1 1/2 mins, and had advised affirmative. Ntap shows light transport only descended at 1500 FPM which was not considered or expected to be a good rate of descent. Sector was staffed with a D controller and supervisor was standing behind the sector at time of occurrence.

Related reports:

Google
 

Original NASA ASRS Text

Title: ARTCC CTLR HAD LESS THAN STANDARD SEPARATION BETWEEN LTT DESCENDING AND WDB ENROUTE OPPOSITE DIRECTION TRAFFIC.

Narrative: WDB X EBND AT FL370. LTT Y WBOUND AT FL390. THE LTT Y REQUESTED LOWER SINCE HE WAS LNDG AT COLUMBUS, OH. THE CTLR KNEW IT WOULD BE CLOSE, BUT THOUGHT THE LTT Y COULD MAKE A GOOD RATE DOWN. AFTER 2 RADAR UPDATES, IT BECAME APPARENT THAT VERT SEP WOULD NOT EXIST AND AVOIDANCE VECTORS WERE ISSUED TO BOTH ACFT. IT WAS SIMPLY AN ERROR IN JUDGEMENT. DIFFERENT PLTS FLY THE SAME ACFT DIFFERENTLY, AND IN THE SITUATION I FELT IT SHOULD HAVE WORKED. WORKLOAD WAS HVY, BUT NOT UNMANAGEABLE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR SPECIFIED TYPE ACR ACFT AS WDB. COMPUTER ONLY HAD ONE HIT AT 4.3 NM AND SHOWED 1600'. CONSIDERED A MINOR INFRINGEMENT. TFC ADVISORY WAS GIVEN BOTH ACFT AND LTT HAD TFC INFO BEFORE DSCNT CLRNC WAS GIVEN. LTT WAS ASKED IF HE COULD BE LEVEL AT FL350 IN 1 1/2 MINS, AND HAD ADVISED AFFIRMATIVE. NTAP SHOWS LTT ONLY DSNDED AT 1500 FPM WHICH WAS NOT CONSIDERED OR EXPECTED TO BE A GOOD RATE OF DSCNT. SECTOR WAS STAFFED WITH A D CTLR AND SUPVR WAS STANDING BEHIND THE SECTOR AT TIME OF OCCURRENCE.

Data retrieved from NASA's ASRS site as of August 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.