ARTCC radar controller failed to maintain standard separation between two aircraft under his control...

Attributes
ACN	149413
Time
Date	199006
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : jau
State Reference	TN
Altitude	msl bound lower : 29000 msl bound upper : 29700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Heavy Transport, Low Wing, 4 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 1
ASRS Report	149413
Person 2
Affiliation	government : faa
Function	oversight : coordinator
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 25200 vertical : 700
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

Medium large transport westbound to stl at FL310. Heavy transport nwbnd at FL310. Large transport northbound at FL290; large transport mia to cle. Medium large transport turned 20 degree left to vector behind heavy transport. Heavy transport turned 10 degree left. At the time of the turns radar coordinator plugged in to do coordination. Medium large transport and heavy transport are being handed off to next sector. Next sector does not realize that I am providing sep between heavy transport and medium large transport. Next sector requests heavy transport descended to FL280. At ths time large transport is turning back from an east heading for spacing now direct to tvt, approximately V360 degree magnetic heading. Didn't foresee large transport at FL290 and heavy transport descending to FL280 as being traffic. At this time heavy transport was stopped at FL290 for additional traffic. At this time I noticed heavy transport in confliction with large transport. Heavy transport was turned to a 010 degree heading and large transport descended to FL2380. Heavy transport was told to expedite descent for medium large transport at FL310. Sep was not maintained between large transport and heavy transport. I believe if coordination had been clrer in the beginning between medium large transport and heavy transport the event would not have occurred. Also, had I realized that large transport would have gained so much speed with the turn back north (wind out of the southwest) I could have helped to maintain sep.

Original NASA ASRS Text

Title: ARTCC RADAR CTLR FAILED TO MAINTAIN STANDARD SEPARATION BETWEEN TWO ACFT UNDER HIS CONTROL.

Narrative: MLG WBND TO STL AT FL310. HVT NWBND AT FL310. LGT NBND AT FL290; LGT MIA TO CLE. MLG TURNED 20 DEG L TO VECTOR BEHIND HVT. HVT TURNED 10 DEG L. AT THE TIME OF THE TURNS RADAR COORDINATOR PLUGGED IN TO DO COORD. MLG AND HVT ARE BEING HANDED OFF TO NEXT SECTOR. NEXT SECTOR DOES NOT REALIZE THAT I AM PROVIDING SEP BTWN HVT AND MLG. NEXT SECTOR REQUESTS HVT DSNDED TO FL280. AT THS TIME LGT IS TURNING BACK FROM AN E HDG FOR SPACING NOW DIRECT TO TVT, APPROX V360 DEG MAGNETIC HDG. DIDN'T FORESEE LGT AT FL290 AND HVT DSNDING TO FL280 AS BEING TFC. AT THIS TIME HVT WAS STOPPED AT FL290 FOR ADDITIONAL TFC. AT THIS TIME I NOTICED HVT IN CONFLICTION WITH LGT. HVT WAS TURNED TO A 010 DEG HDG AND LGT DSNDED TO FL2380. HVT WAS TOLD TO EXPEDITE DSNT FOR MLG AT FL310. SEP WAS NOT MAINTAINED BTWN LGT AND HVT. I BELIEVE IF COORD HAD BEEN CLRER IN THE BEGINNING BTWN MLG AND HVT THE EVENT WOULD NOT HAVE OCCURRED. ALSO, HAD I REALIZED THAT LGT WOULD HAVE GAINED SO MUCH SPD WITH THE TURN BACK N (WIND OUT OF THE SW) I COULD HAVE HELPED TO MAINTAIN SEP.

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.