Light transport X had less than standard separation from light transport Y. System error.

Attributes
ACN	154506
Time
Date	199008
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : thx
State Reference	TX
Altitude	msl bound lower : 25000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu
Operator	general aviation : personal
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 2 controller radar : 1
ASRS Report	154506
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
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 : 18000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Light transport X was level FL260 en route over thx to czt. Light transport Y departed sat and was issued a climb to FL250. After this, I began working on sep and sequencing between a departure and several arrs to mfe and hrl airports. Light transport X called me and was issued a pilot's discretion descent to 6000'. 1 min later light transport Y requested a higher altitude. The C/a began flashing and I became aware of an imminent loss of minimum sep. I issued a turn and climb to light transport Y in order to reestablish sep.

Original NASA ASRS Text

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

Narrative: LTT X WAS LEVEL FL260 ENRTE OVER THX TO CZT. LTT Y DEPARTED SAT AND WAS ISSUED A CLB TO FL250. AFTER THIS, I BEGAN WORKING ON SEP AND SEQUENCING BTWN A DEP AND SEVERAL ARRS TO MFE AND HRL ARPTS. LTT X CALLED ME AND WAS ISSUED A PLT'S DISCRETION DSNT TO 6000'. 1 MIN LATER LTT Y REQUESTED A HIGHER ALT. THE C/A BEGAN FLASHING AND I BECAME AWARE OF AN IMMINENT LOSS OF MINIMUM SEP. I ISSUED A TURN AND CLB TO LTT Y IN ORDER TO REESTABLISH 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.