Air carrier X had less than standard separation from air carrier Y. System error.

Attributes
ACN	129576
Time
Date	198911
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : orf
State Reference	VA
Altitude	msl bound lower : 28000 msl bound upper : 29000
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
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 : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar controller : developmental
ASRS Report	129576
Person 2
Affiliation	government : faa
Function	oversight : supervisor
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 other other : unspecified atc
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 10200 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was vectoring jfk arrs for spacing while trying to eliminate confliction with 4 aircraft on an unusual crossing route so a lot of aircraft were being vectored and speed adjusted. Air carrier X at FL290 needed to be descended for arrival to phl. Because of overlapping data tags, I didn't see air carrier Y at FL280 15 NM in front of air carrier X. Air carrier X was issued descent clearance to FL240 through air carrier Y. The asic pointed out air carrier Y and my initial reaction was to abort air carrier X descent. I was in the process of doing that when the supervisor said turn them both and expedite air carrier X's descent. I corrected the clearance I was in the process of giving and turned both aircraft 30 degrees right and expedited air carrier X descent. Sep was reduced to 1.7 mi, 300'. Traffic was issued aircraft, but did not report traffic in sight.

Original NASA ASRS Text

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

Narrative: I WAS VECTORING JFK ARRS FOR SPACING WHILE TRYING TO ELIMINATE CONFLICTION WITH 4 ACFT ON AN UNUSUAL XING ROUTE SO A LOT OF ACFT WERE BEING VECTORED AND SPD ADJUSTED. ACR X AT FL290 NEEDED TO BE DSNDED FOR ARR TO PHL. BECAUSE OF OVERLAPPING DATA TAGS, I DIDN'T SEE ACR Y AT FL280 15 NM IN FRONT OF ACR X. ACR X WAS ISSUED DSCNT CLRNC TO FL240 THROUGH ACR Y. THE ASIC POINTED OUT ACR Y AND MY INITIAL REACTION WAS TO ABORT ACR X DSCNT. I WAS IN THE PROCESS OF DOING THAT WHEN THE SUPVR SAID TURN THEM BOTH AND EXPEDITE ACR X'S DSCNT. I CORRECTED THE CLRNC I WAS IN THE PROCESS OF GIVING AND TURNED BOTH ACFT 30 DEGS RIGHT AND EXPEDITED ACR X DSCNT. SEP WAS REDUCED TO 1.7 MI, 300'. TFC WAS ISSUED ACFT, BUT DID NOT RPT TFC IN SIGHT.

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.