ARTCC controller inadvertently cleared an small transport to same altitude as other small transport going same direction. Controller missed readback and computer detected less than standard separation.

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Attributes
ACN	87930
Time
Date	198805
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fwa
State Reference	IN
Altitude	msl bound lower : 17400 msl bound upper : 18000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : developmental controller : radar
Experience	controller non radar : 1
ASRS Report	87930
Person 2
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 21000 vertical : 600
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

The 2 aircraft were basically on the same flight path, one at FL180 and the other was at 17000' requesting FL220. To expedite the small transport X climb I turned the 17000' traffic 20 degrees left and turned the small transport Y at FL180 30 degrees right. As I issued the 20 degree left turn I transposed the 2 altitudes and told the small transport X to maintain FL180. As the small transport X was reading back the clearance the controller adjacent to me told me to issue a speed of 280 KTS to an aircraft I was handing off to him. Consequently, I missed the readback. Callback conversation with reporter revealed the following: type aircraft involved and proximity of aircraft when computer detected error. Location was given as 40 mi west of fwa in other controled airspace. Traffic volume was light to moderate and reporter did have a D controller on sector with him. Reporter is developmental controller that is fully certified on the radar position he was working. Traffic advisory was given, but traffic not sighted and no other action taken as aircraft were diverging.

Original NASA ASRS Text

Title: ARTCC CTLR INADVERTENTLY CLEARED AN SMT TO SAME ALT AS OTHER SMT GOING SAME DIRECTION. CTLR MISSED READBACK AND COMPUTER DETECTED LESS THAN STANDARD SEPARATION.

Narrative: THE 2 ACFT WERE BASICALLY ON THE SAME FLT PATH, ONE AT FL180 AND THE OTHER WAS AT 17000' REQUESTING FL220. TO EXPEDITE THE SMT X CLB I TURNED THE 17000' TFC 20 DEGS LEFT AND TURNED THE SMT Y AT FL180 30 DEGS RIGHT. AS I ISSUED THE 20 DEG LEFT TURN I TRANSPOSED THE 2 ALTS AND TOLD THE SMT X TO MAINTAIN FL180. AS THE SMT X WAS READING BACK THE CLRNC THE CTLR ADJACENT TO ME TOLD ME TO ISSUE A SPD OF 280 KTS TO AN ACFT I WAS HANDING OFF TO HIM. CONSEQUENTLY, I MISSED THE READBACK. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: TYPE ACFT INVOLVED AND PROX OF ACFT WHEN COMPUTER DETECTED ERROR. LOCATION WAS GIVEN AS 40 MI W OF FWA IN OTHER CTLED AIRSPACE. TFC VOLUME WAS LIGHT TO MODERATE AND RPTR DID HAVE A D CTLR ON SECTOR WITH HIM. RPTR IS DEVELOPMENTAL CTLR THAT IS FULLY CERTIFIED ON THE RADAR POS HE WAS WORKING. TFC ADVISORY WAS GIVEN, BUT TFC NOT SIGHTED AND NO OTHER ACTION TAKEN AS ACFT WERE DIVERGING.

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.