Atx X had less than standard separation from aircraft Y. System error.

Attributes
ACN	155050
Time
Date	199008
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ldn
State Reference	VA
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air taxi
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other descent other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 3 controller radar : 1
ASRS Report	155050
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 4800 vertical : 800
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

XX30: dulles approach control gave control for atx X swbnd at 8000' MSL on V143 to climb to 10000' MSL. XX35: atx X issued climb clearance to 10000'. XX36: accepted radar handoff on aircraft Y westbound climbing to 10000'. XX38: I observed a potential loss of sep between atx X and aircraft Y. I asked atx X to say altitude and issued atx X immediate descent to 9000'. Also climbed aircraft Y to 11000'.

Original NASA ASRS Text

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

Narrative: XX30: DULLES APCH CTL GAVE CTL FOR ATX X SWBND AT 8000' MSL ON V143 TO CLB TO 10000' MSL. XX35: ATX X ISSUED CLB CLRNC TO 10000'. XX36: ACCEPTED RADAR HDOF ON ACFT Y WBND CLBING TO 10000'. XX38: I OBSERVED A POTENTIAL LOSS OF SEP BTWN ATX X AND ACFT Y. I ASKED ATX X TO SAY ALT AND ISSUED ATX X IMMEDIATE DSNT TO 9000'. ALSO CLBED ACFT Y TO 11000'.

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.