Air carrier was descended to an occupied altitude resulting less than standard separation.

Attributes
ACN	142791
Time
Date	199004
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cty
State Reference	FL
Altitude	msl bound lower : 30700 msl bound upper : 32000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute airway : j43
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Fighter
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 8 controller radar : 6
ASRS Report	142781
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 10200 vertical : 1300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was southbound on J43 at FL330. Military Y fgt was northbound on a vector around air carrier X at FL310 (on J43 normally used as a solely southbound arwy). Air carrier X requested lower altitude because of turbulence and I assigned him FL290, not realizing the potential conflict with military Y. I feel I was somewhat distracted by the requirement to watch primary radar on this high altitude sector and the subsequent clutter it creates. I also was distracted from this situation while involved in intrailing ord landing traffic to adhere to flow control restrictions. When the conflict was noticed I stopped the descent of air carrier X and instructed him to climb back to FL30 (at FL326 at the time). Military Y was vectored to a heading of 280 degrees and descended to FL270. The vector and the heading were not sufficient to maintain sep. Air carrier X was descended to FL320 before he could start his climb back to FL330. At their closest point the aircraft were 1.7 mi latitude and 1300' vertical.

Original NASA ASRS Text

Title: ACR WAS DESCENDED TO AN OCCUPIED ALT RESULTING LESS THAN STANDARD SEPARATION.

Narrative: ACR X WAS SBND ON J43 AT FL330. MIL Y FGT WAS NBOUND ON A VECTOR AROUND ACR X AT FL310 (ON J43 NORMALLY USED AS A SOLELY SBND ARWY). ACR X REQUESTED LOWER ALT BECAUSE OF TURB AND I ASSIGNED HIM FL290, NOT REALIZING THE POTENTIAL CONFLICT WITH MIL Y. I FEEL I WAS SOMEWHAT DISTRACTED BY THE REQUIREMENT TO WATCH PRIMARY RADAR ON THIS HIGH ALT SECTOR AND THE SUBSEQUENT CLUTTER IT CREATES. I ALSO WAS DISTRACTED FROM THIS SITUATION WHILE INVOLVED IN INTRAILING ORD LNDG TFC TO ADHERE TO FLOW CTL RESTRICTIONS. WHEN THE CONFLICT WAS NOTICED I STOPPED THE DSNT OF ACR X AND INSTRUCTED HIM TO CLB BACK TO FL30 (AT FL326 AT THE TIME). MIL Y WAS VECTORED TO A HDG OF 280 DEGS AND DSNDED TO FL270. THE VECTOR AND THE HDG WERE NOT SUFFICIENT TO MAINTAIN SEP. ACR X WAS DSNDED TO FL320 BEFORE HE COULD START HIS CLB BACK TO FL330. AT THEIR CLOSEST POINT THE ACFT WERE 1.7 MI LAT AND 1300' VERT.

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.