Less than standard separation between uga X and uga Y. System error.

Attributes
ACN	281167
Time
Date	199408
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : loz
State Reference	KY
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Make Model Name	Bonanza 35
Operating Under FAR Part	other : unknown
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Make Model Name	PA-28 Cherokee/Archer II/Dakota/Pillan/Warrior
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 24
ASRS Report	281167
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Events
Anomaly	non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance none taken : anomaly accepted other
Consequence	Other
Miss Distance	horizontal : 24600 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Uga X departed loz climbing to 4000 ft, a BE35. Uga Y on frequency sbound V97 over loz at 5000 ft, a PA28. Uga Z northbound at 6000 ft was 15 mi south of loz arriving, a BE55. Having observed the departing uga X, I turned uga Z to a 300 degree heading and descended to 4000 ft, reaching 4000 ft cleared direct loz. Uga X was idented and turned to a 100 degree heading to clear the arrival path for uga Z. When uga Z turned direct to loz, I was unsure of maintaining 5 mi. I then checked distance between uga X and uga Y and determined I had 5.5 mi and increasing so I issued uga X a 090 degree heading and 6000 ft. When I observed that the eastbound heading was losing distance, I turned uga Y to a 270 degree heading but not soon enough to prevent a loss of separation. Callback conversation with reporter revealed the following information: reporter stated that the aircraft were on diverging courses. Reporter lost separation after turning lead aircraft perpendicular to the established course of the trailing aircraft which allowed the interval between aircraft to close to less than was required.

Original NASA ASRS Text

Title: LTSS BTWN UGA X AND UGA Y. SYS ERROR.

Narrative: UGA X DEPARTED LOZ CLBING TO 4000 FT, A BE35. UGA Y ON FREQ SBOUND V97 OVER LOZ AT 5000 FT, A PA28. UGA Z NBOUND AT 6000 FT WAS 15 MI S OF LOZ ARRIVING, A BE55. HAVING OBSERVED THE DEPARTING UGA X, I TURNED UGA Z TO A 300 DEG HDG AND DSNDED TO 4000 FT, REACHING 4000 FT CLRED DIRECT LOZ. UGA X WAS IDENTED AND TURNED TO A 100 DEG HDG TO CLR THE ARR PATH FOR UGA Z. WHEN UGA Z TURNED DIRECT TO LOZ, I WAS UNSURE OF MAINTAINING 5 MI. I THEN CHKED DISTANCE BTWN UGA X AND UGA Y AND DETERMINED I HAD 5.5 MI AND INCREASING SO I ISSUED UGA X A 090 DEG HDG AND 6000 FT. WHEN I OBSERVED THAT THE EBOUND HDG WAS LOSING DISTANCE, I TURNED UGA Y TO A 270 DEG HDG BUT NOT SOON ENOUGH TO PREVENT A LOSS OF SEPARATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE ACFT WERE ON DIVERGING COURSES. RPTR LOST SEPARATION AFTER TURNING LEAD ACFT PERPENDICULAR TO THE ESTABLISHED COURSE OF THE TRAILING ACFT WHICH ALLOWED THE INTERVAL BTWN ACFT TO CLOSE TO LESS THAN WAS REQUIRED.

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.