Aircraft was descended to an altitude that conflicted with another aircraft. Operational error.

Attributes
ACN	103311
Time
Date	198902
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cll
State Reference	TX
Altitude	msl bound lower : 17000 msl bound upper : 17000
Environment
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zhu
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	103311
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I assigned large transport an altitude based on his rate of descent and altitude of other traffic. I misread the mode C of large transport making him 1000' higher than I figured he would be.

Original NASA ASRS Text

Title: ACFT WAS DESCENDED TO AN ALT THAT CONFLICTED WITH ANOTHER ACFT. OPERATIONAL ERROR.

Narrative: I ASSIGNED LGT AN ALT BASED ON HIS RATE OF DSCNT AND ALT OF OTHER TFC. I MISREAD THE MODE C OF LGT MAKING HIM 1000' HIGHER THAN I FIGURED HE WOULD BE.

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.