ZHU controller apparently overlooks developing conflict until separation is lost.

Attributes
ACN	528769
Time
Date	200110
Day	Sun
Place
Locale Reference	navaid : das.vortac
State Reference	TX
Altitude	msl bound lower : 31000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	B737-500
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar pilot : private
Experience	controller time certified in position1 : 0.5 flight time total : 50
ASRS Report	528769
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 24600 vertical : 1100
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was sequencing aircraft into the houston terminal area. I turned the front aircraft to a 150 degree heading. I turned the following aircraft to a 150 degree heading. Descended the front aircraft to FL310. At approximately XA10Z I lost separation.

Original NASA ASRS Text

Title: ZHU CTLR APPARENTLY OVERLOOKS DEVELOPING CONFLICT UNTIL SEPARATION IS LOST.

Narrative: I WAS SEQUENCING ACFT INTO THE HOUSTON TERMINAL AREA. I TURNED THE FRONT ACFT TO A 150 DEG HDG. I TURNED THE FOLLOWING ACFT TO A 150 DEG HDG. DSNDED THE FRONT ACFT TO FL310. AT APPROX XA10Z I LOST SEPARATION.

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.